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Sensors and Actuators A: Physical
Journal Prestige (SJR): 0.699
Citation Impact (citeScore): 3
Number of Followers: 182  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0924-4247 - ISSN (Online) 0924-4247
Published by Elsevier Homepage  [3161 journals]
  • Dual-surface lens with ring-shaped structures for optical tuning of GaN
           ultraviolet photodetectors at low temperature
    • Abstract: Publication date: 1 March 2020Source: Sensors and Actuators A: Physical, Volume 303Author(s): Sanghun Shin, Beomchan Kang, Hongyun SoThis study aims to enhance the optical sensitivity of gallium nitride ultraviolet (UV) photodetectors at low temperatures using a multifunctional microlens with ring-shaped structures. This dual-surface lens with ring-shaped structures (i.e., DSLR), a unique microlens, was fabricated by employing a curable polymer and three-dimensional printed mold, and it has two primary regions: An upper and a lower region. The upper region of the DSLR serves as a smooth lens surface to focus the incident UV rays by delaying frost formation at low temperatures. The lower region captures condensed water droplets, thus allowing for only local frost formation. When compared to a photodetector without the DSLR, the photodetector covered by the DSLR generated a higher photocurrent at low temperatures (corresponding to a ∼13.85% increase in generated photocurrent in the temperature range of −20 °C to −1.2 °C). Thus, the findings of this study support the use of a facile, cost-effective, and multifunctional dual-surface polymer lens for higher-sensitivity UV detection in various low-temperature environments, such as the Arctic, outer space, and the environment within cryostats.Graphical abstractGraphical abstract for this article
       
  • Microelectromechanical system-based, high-finesse, optical fiber
           Fabry–Perot interferometric pressure sensors
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): Weiyi Ma, Yi Jiang, Jie Hu, Lan Jiang, Taojie Zhang, Taojie ZhangA high-finesse, optical fiber, extrinsic Fabry–Perot interferometric (EFPI) pressure sensor based on a microelectromechanical system (MEMS) technique is proposed and experimentally demonstrated. The essential element in the pressure sensor is the high-finesse EFPI cavity that consists of a Pyrex glass wafer, a micromachined silicon wafer, and highly reflective dielectric films. Another Pyrex glass is used for fixing an optical fiber collimator, which allows the realization of the alignment of the incident light. Experimental results show that the proposed sensor exhibits a pressure sensitivity of 1.598 μm/MPa and a high-pressure sensing resolution of 0.002% of the full scale. This sensor is expected to benefit many applications that require high-accuracy pressure measurements, and especially atmospheric pressure applications.Graphical abstractGraphical abstract for this article
       
  • Quadruple Sensitivity Improvement for Wind Speed Sensor using Dual-layer
           Bended Inductors
    • Abstract: Publication date: Available online 17 January 2020Source: Sensors and Actuators A: PhysicalAuthor(s): Zhenxiang Yi, Yu Wan, Ming Qin, Qing-An HuangIn this paper, a novel wind speed sensor with dual layer inductors is proposed to realize improved sensitivity for the first time. Two inductors with same structure are fabricated on front and back surface of the flexible substrate. When the wind blows towards the substrate, the two inductors on both sides bend because of wind pressure. Consequently, the total inductance variation, as a measure for the wind speed, can be increased effectively because of mutual inductance effect. The proposed anemometer is fabricated on polyethylene terephthalate (PET) substrate. Wind speed experiments are performed in the special wind tunnel and the LCR meter is applied to record the inductance variation. It demonstrates that, compared to single-layer inductors, the dual-layer design can achieve a quadruple sensitivity for the wind speed up to 11.2m/s. The reason is that the mutual inductance contributes to the total variation equally as the two self inductance.Graphical abstractGraphical abstract for this article
       
  • Nanoparticle orientation distribution analysis and design for polymeric
           piezoresistive sensors
    • Abstract: Publication date: Available online 17 January 2020Source: Sensors and Actuators A: PhysicalAuthor(s): Marianne Fletcher Clayton, R. Adam Bilodeau, Anton E. Bowden, David T. FullwoodPiezoresistive sensors, with polymer matrices and conductive nanoparticles, are a relatively new addition to the sensor class, with the potential to transform such fields as wearable sensors and the internet of things. The unusual inverse piezoresistive behavior of the sensors has been modeled using quantum tunneling and percolation theory. However, the impact of the distribution of conductive particles in the matrix, and specifically their relative orientation, has not been well studied. The initial and deformed distribution of orientations greatly influences the sensor behavior, since the quantum tunneling model is highly sensitive to the polymer gaps between nanoparticles; the evolution of these gaps under deformation is strongly dependent upon the relative orientation of neighboring particles, and determines electron transport properties, and overall sensor response. In this paper a simple analytical model for isotropic orientation distribution and subsequent Poisson-based gap evolution is compared with a more sophisticated finite element and random resistor network analysis. The new numerical model was able to explain previously unexplained physical behavior and is used to design sensors with specific desired characteristics. The appropriateness of the previously assumed percolation behavior is also examined via the model and generalized effective medium theory.Graphical Graphical abstract for this article
       
  • Experimental and numerical analyses of a rotary motor using shape memory
           alloy mini springs
    • Abstract: Publication date: Available online 31 December 2019Source: Sensors and Actuators A: PhysicalAuthor(s): José M.B. Sobrinho, F.M.F. Filho, A. Emiliavaca, Maxsuel F. Cunha, Cícero R. Souto, S.A. Silva, Andreas RiesThe rotation mechanism based on an eccentric, combined with large deformations of SMA spring type actuators, allowed the design of a compact device with continuous rotation. The proposed rotary motor is driven by NiTi shape memory alloy (SMA) springs. The springs are driven by an electric current using the Joule effect as a physical principle. In this case, the motor can rotate in both directions, by only inverting the drive sequence. When driven, SMA springs combine the superelastic effect (SE) and the shape memory effect (SME), and can suffer deformations of up to 600% of their initial length. To define the design parameters, an electro-thermomechanical characterization of the SMA springs was performed, in addition to antagonistic tests to evaluate the generation of work after thermal heating. An experimental set-up measured the angular displacement, force and torque responses generated by the motor. For the numerical simulations, three different models were tested in order to define which of them best represents the behavior of force and deflection of the actuators. The most appropriate model was selected for the analyses of the static responses of the motor in rotation. The operation of the prototype was demonstrated for different driving modes, presenting results of movement, force, torque and temperature of the actuators. Numerical simulations presented a maximum error of 5.13% when compared to the experiment. The contribution of this work are numerical simulations of a rotating motor, correlated with experimental measurements. It is demonstrated that the proposed motor is in a prominent position regarding its torque/volume and torque/mass ratios when compared to other motors of the same class.Graphical abstractGraphical abstract for this article
       
  • New corn-based sacrificial layer for MEMS based on screen-printed PZT
           ceramics
    • Abstract: Publication date: Available online 31 December 2019Source: Sensors and Actuators A: PhysicalAuthor(s): Simon Grall, Onuma Santawitee, Isabelle Dufour, Vincent Aubry, Hélène DebédaThis paper demonstrates the use of a new screen-printed corn starch-based sacrificial layer that decomposes entirely thermally at ∼550∘C. A comparison with a polyester-based sacrificial layer used in previous work is made. Both are used to make PZT microcantilevers and discs in a fully screen-printed fabrication process. Both designs are released during the sintering of the ceramics at 900∘C using the new sacrificial layer, with porosities of 6.7% and 2.2% for microcantilevers and discs, respectively.Graphical abstractGraphical abstract for this article
       
  • Multi-perspective collaborative scheduling using extended genetic
           
    • Abstract: Publication date: Available online 31 December 2019Source: Sensors and Actuators A: PhysicalAuthor(s): Wenyu Zhang, Jiepin Ding, Yan Wang, Shuai Zhang, Zhiying XiongScheduling multiple heterogeneous tasks in a manufacturing system to satisfy customized requirements becomes challenging, especially in uncertain manufacturing environment. In cloud manufacturing, a serious problem is to schedule multiple heterogeneous tasks to balance the benefit conflicts among customers, manufacturing enterprises, and manufacturing platform comprehensively. Therefore, this study formulates the multi-task scheduling problem mathematically as a new fuzzy mixed-integer linear programming (FMILP) model based on multi-perspective collaborative optimization and fuzzy set theory. To solve the FMILP model, an extended genetic algorithm (EGA) with the interval-valued intuitionistic fuzzy entropy weight (IVIFEW) method is proposed. The IVIFEW method is adapted to obtain the preference of QoS attributes and task priority. In addition, the basic genetic algorithm is improved by integrating a migration operator, local search, and restart strategy to maintain the diversity of population and enhance the exploitation ability. A suitable parameter combination of EGA is found in a series of experiments based on the Taguchi method. The experimental results demonstrate that the proposed EGA solves the FMILP model effectively, providing better optimal solutions compared with the baseline algorithms.Graphical abstractGraphical abstract for this article
       
  • Distributed optical fiber sensing of micron-scale particles
    • Abstract: Publication date: Available online 20 November 2019Source: Sensors and Actuators A: PhysicalAuthor(s): Lu Peng, Jiawen Li, Robert A. McLaughlin, Heike Ebendorff-Heidepriem, Stephen C. Warren-SmithDistributed sensing of micron-scale particles is achieved with an exposed-core microstructured optical fiber using optical frequency domain reflectometry. The reference and sample signals of the interferometer are generated in the same fiber path, which gives this fully fiber-integrated sensor the potential to be used as a portable probe for in-vivo sensing. This sensing concept has great advantages over reported single-point fiber sensors due to its distributed sensing property. We demonstrate the technique using 10 μm polystyrene beads, by detecting their locations along the fiber through backscatter of the exposed-core fiber’s evanescent field. A simplified theoretical model is proposed to estimate the relationship between the particle’s size and detection distance after considering the system’s inherent losses. The proposed sensing platform offers opportunities for distributed sensing of biological targets.Graphical abstractGraphical abstract for this article
       
  • A review of railway infrastructure monitoring using fiber optic sensors
    • Abstract: Publication date: Available online 12 November 2019Source: Sensors and Actuators A: PhysicalAuthor(s): Cong Du, Susom Dutta, Pradeep Kurup, Tzuyang Yu, Xingwei WangIn recent years, railway infrastructures and systems have played a significant role as a highly efficient transportation mode to meet the growing demand in transporting both cargo and passengers. Application of these structures in extreme environmental situation under severe working and loading conditions, caused by the traffic growth, heavier axles and vehicles and increase in speed makes it extremely susceptible to degradation and failure. In the last two decades, a significant number of innovative sensing technologies based on fiber optic sensors (FOS) have been utilized for structural health monitoring (SHM) due to their inherent distinctive advantages, such as small size, light weight, immunity to electromagnetic interference (EMI) and corrosion, and embedding capability. Fiber optic-based monitoring systems use quasi-distributed and continuously distributed sensing techniques for real time measurement and long term assessment of structural properties. This allows for early stage damage detection and characterization, leading to timely remediation and prevention of catastrophic failures. In this scenario, FOS have been proved to be a powerful tool for meticulous assessment of railway systems including train and track behavior by enabling real-time data collection, inspection and detection of structural degradation. This article reviews the current state-of-the-art of fiber optic sensing/monitoring technologies, including the basic principles of various optical fiber sensors, novel sensing and computational methodologies, and practical applications for railway infrastructure monitoring. Additionally, application of these technologies to monitor temperature, stresses, displacements, strain measurements, train speed, mass and location, axle counting, wheel imperfections, rail settlements, wear and tear and health assessment of railway bridges and tunnels will be thoroughly discussed.Graphical abstractGraphical abstract for this article
       
  • Design and verification of a wireless sensing system for monitoring
           large-range ground movement
    • Abstract: Publication date: Available online 12 November 2019Source: Sensors and Actuators A: PhysicalAuthor(s): Chuncheng Yao, Chengyu Hong, Dong Su, Yifan Zhang, Zhenyu YinAbstractIn this study, flex sensors and Bluetooth wireless transmission technology were combined to fabricate a wireless sensing system for monitoring ground movement. A typical hinge joint structure was designed and fabricated to embed flex sensors. A number of these typical hinge joint elements were used to measure distributed ground movement. Calibration tests show that minimum resolution, sensitivity, and measurement range of flex sensors were 0.5°, 2.0–2.3 count/° and −30°∼+70°, respectively. In experimental study, five flex sensors were placed inside a slope model for both soil settlement and horizontal displacement measurement. Calculated settlement of the data measured from flex sensors were verified with the output data of Linear Variable Displacement Transducer (LVDT), and the obtained maximum errors were less than 0.5 mm when the maximum ground displacement was approached. Besides, the calulated horizontal soil displacement from measurement of flex sensors has proved that flex sensors can be applied for monitoring soil movement when large ground deformation occurs.
       
  • On The Steady Incompressible Laminar Saltwater Flow In Minkowski 2-D
           Subspace Continuum Through A Rectangular MHD Micro-pump
    • Abstract: Publication date: Available online 11 November 2019Source: Sensors and Actuators A: PhysicalAuthor(s): Aly Maher Abourabia, Sara Ali Abdel MoneimBackgroundThe problem of a steady, incompressible and fully developed laminar fluid flow is discussed. This study focuses on the predictions of the pumping performance of 1 M NaCl solution.MethodThe corresponding Navier-Stokes momentum (MHD) equations are solved analytically by introducing a new ansatz combining the wave-position characters of the flow modelled in Minkowski 2-D subspace continuum subjected to suitable boundary conditions.ResultsSolving for the velocity profile of the working fluid across the micro-channel; the obtained solutions which include the dimensional flow velocity, volumetric flow rate, average velocity and pressure gradient are plotted under various operating currents, magnetic flux densities and micro-channel aspect ratio values.ConclusionsOur results provide that increasing high ratios of the electrode to channel lengths serves to attain more coverable channel area. It is also noted that an excess of the applied fields tends to compensate the velocity degradation for deep channel configuration. Graphics show that the decreased friction force between the channel top and bottom is a preferable factor to improve the process in practice. Our results may be useful to shed light on studying the microfluidic systems flow.Graphical abstractGraphical abstract for this article
       
  • An RF backscatterer system for real-time multi-sensing applications
    • Abstract: Publication date: Available online 11 November 2019Source: Sensors and Actuators A: PhysicalAuthor(s): Deepak Kumar, Saikat Mondal, Amanpreet Kaur, Yiming Deng, Premjeet ChahalIn this paper, a power-efficient passive analog frequency modulation based RF system is proposed for real-time communication with multiple sensor elements for internet-of-things (IoT) based smart applications. The proposed RF tag with integrated sensors uses an onboard ultra low power oscillator to generate a single frequency modulation signal unique to each of the sensor elements. The generated single tone frequency is modulated to generate the backscattered RF signal, which is immune to the interference present in the propagating environment. The maximum power required for continuous operation of the sensing oscillator is 30 μW, which is harvested from the received RF signal. The designed multi-sensor RF tag has a sensitivity of −6 dBm and has the capacity to integrate up to six different sensors within the available single channel RFID bandwidth of 300 kHz. The wireless communication distance of 10 ft is achieved due to the low power consumption of the multi-sensor RF tag. A passive RF tag with two example sensing elements; temperature and luminescence are demonstrated. The temperature and luminescence change from 25 °C to 60 °C and from 0 to 20 footcandle (lumen/ft2) is represented by 75–100 kHz and 125–150 kHz frequency range, respectively.Graphical abstractGraphical abstract for this article
       
  • A novel linear inertial piezoelectric actuator based on asymmetric
           clamping materials
    • Abstract: Publication date: Available online 11 November 2019Source: Sensors and Actuators A: PhysicalAuthor(s): Dezhu Shen, Jianming Wen, Jijie Ma, Yili Hu, Renming Wang, Jianping LiAsymmetric inertial piezoelectric actuators are driven by the inertial impact difference between the forward and backward cycle. Typical ways to create inertial impact difference involve the application of asymmetric driving signals and clamping blocks with different dimensions. A new asymmetric inertial piezoelectric actuator using clamping blocks with asymmetric materials is proposed in this study. The block materials have different elastic modulus, which generate different inertial impact forces to drive the actuator. The relationship between the vibrator displacement and the elastic modulus difference of the clamping blocks are investigated by comparison of the FEM and theoretical results. A series of experiments are conducted to prove the feasibility of the proposed actuator. The actuator with steel-copper clamping materials achieves more stable working performance compared with other clamping materials, the minimum step displacement, repeatability parameter reaches 2.0 μm, 0.566 μm and 15.7 μm, 4.805 μm in non-resonant and resonant states under the signal of Vp-p = 15 V, respectively. The results show the proposed actuator works smoothly in both in non-resonant and resonant states, which provides a new reference for the application of inertial piezoelectric actuators.Graphical abstractGraphical abstract for this article
       
  • Novel multi-degrees of freedom optical table dynamometer for force
           measurements
    • Abstract: Publication date: Available online 11 November 2019Source: Sensors and Actuators A: PhysicalAuthor(s): Allen Sandwell, Jihyun Lee, Chaneel Park, Simon S. ParkThis paper proposes a configuration of novel table dynamometer that was developed based on laser optics to accurately measure multi-axis static and dynamic forces. Optical components are incorporated, and photodetector technologies are applied to measure positional changes on the order of nanometers. Mathematical algorithms using the optical system’s geometry are proposed to identify both the incident position and the laser beam’s trajectory on the photodetector. Vertical oscillation of the photodetector lets the algorithms decouple translational and rotational effects from the measured signals such that positional changes of the target system from external forces can be measured in each axis. A design for a new, two-degree-of-freedom, flexure-based mechanical amplification system improves sensitivity so that, with the proposed algorithms and a single detector, the effects of multiple sources are extracted. A prototype of the proposed configuration is fabricated and used to experimentally investigate sensitivities, bandwidth, and cutting force. The results show that the proposed configuration has good performance in measuring static force along with the potential to improve its dynamic measurements when its hardware is designed with materials of high stiffness.Graphical abstractGraphical abstract for this article
       
  • Usage of the impedance effect of a spiral dual-coil for fingerprint sensor
           application
    • Abstract: Publication date: Available online 11 November 2019Source: Sensors and Actuators A: PhysicalAuthor(s): Shihwei Lin, Mingyu Hsieh, Yuanyuan Huang, Fuchi Shih, Zihsong Hu, Weileun Fang, Chingfu TsouThis paper presents a design concept that uses the impedance effect of a spiral dual-coil array to identify fingerprint patterns. Unlike commercial optical, resistive, and capacitive sensing technologies, this unique dual-coil design enables the measurement of a fingerprint using the effect of the ridges and valleys on electrical impedance. In this study, a typical sensing chip with a 3 × 128 dual-coil array was fabricated by a simple microfabrication process. Variations of the coupling capacitance and mutual inductance were then used to verify the properties of different mediums. For a typical case in ambient air, the measured resonant frequency was 8 MHz, which resulted in a maximum induced current of 1.0 mA and a phase shift of 45.5°. The measurement results for saline solutions with different concentrations showed that mediums with higher conductivity caused larger phase shifts. The sample data resulting from the dual-coil array were successfully used to reconstruct a fingerprint image, with a good match in minutiae.Graphical abstractGraphical abstract for this article
       
  • Electronic textiles based wearable electrotherapy for pain relief
    • Abstract: Publication date: Available online 10 November 2019Source: Sensors and Actuators A: PhysicalAuthor(s): Meijing Liu, Tyler Ward, Dan Young, Helga Matos, Yang Wei, Jo Adams, Kai YangElectrotherapy is a common therapeutic treatment used to provide pain relief. The device delivers a mild level of current via electrodes positioned on the skin to interfere with the pain signal and stimulate the release of the body’s own natural painkiller to reduce the pain. This paper presents the materials and fabrication methods used to manufacture a textile based wearable electronic textile (e-textile) with electrodes embedded for joint pain relief. The electrode is made by three functional layers including textile layer, conductive layer, and electrode layer. An electronic control has been developed to deliver interferential therapy. The e-sleeve has been designed and developed alongside patient and public input and tested on six volunteers with self-reported knee joint pain. Four out of six volunteers reported noticeable pain reduction on using the e-textile. The wearable e-textile demonstrated no adverse effects and pilot evidence suggests this has the potential to be a comfortable and easy to use solution for pain relief for people living with osteoarthritis knee joint pain.Graphical abstractElectrotherapy deviceGraphical abstract for this article
       
  • Behavior of vibration energy harvesters composed of polymer fibers and
           piezoelectric ceramic particles
    • Abstract: Publication date: Available online 10 November 2019Source: Sensors and Actuators A: PhysicalAuthor(s): R. Hasegawa, M. Mehnert, J. Mergheim, P. Steinmann, K. KakimotoFlexible piezoelectric composites of polymer fiber and ceramic particles are promising candidates for ambient vibration energy harvesters. However, observations of stress transfer behavior between polymer fiber and ceramic particle have not been clarified. In this study, the output from two types of composite with ceramic particles inside and outside of the fiber was measured, where the output for ceramic particles inside the fiber was 209 mV and 91 mV for fibers outside. Experimental results were confirmed using a microstructure-based finite element method. A simplified microstructure model that consists of one piezoelectric particle and two polymer fibers was created and loaded with the prescribed strain. Ceramic particle strain inside the fiber was higher than one outside the fiber, which was quantitatively consistent with experimental results. Analysis indicates that stress transfer between the polymer fiber and ceramic particles occurs on the interface and is important for electrical output. This is the first study to clarify the relation between stress transfer and output. Study results will lead to the material design of flexible piezoelectric composites and their application to ambient vibration energy harvesters.Graphical abstractGraphical abstract for this article
       
  • An immersive resonant sensor with microcantilever for pressure measurement
    • Abstract: Publication date: Available online 9 November 2019Source: Sensors and Actuators A: PhysicalAuthor(s): Libo Zhao, Linya Huang, Guoxi Luo, Jiuhong Wang, Hongyan Wang, Yongshun Wu, Zhikang Li, Xiangyang Zhou, Zhuangde JiangA micro electromechanical systems (MEMS) resonant sensing chip with microcantilever has been developed to measure gas pressure by immersing it in gaseous environment. The microcantilever was designed to sense surrounding gas molecules loading, owing to the gas density sensitive to the pressure, then the resonant frequency shifts of sensing chip were induced under different pressures. Especially, the sensing chip featuring no diaphragm realized embedded package and installation for the immersive measurement. The resonance response of the sensing chip for target pressure was theoretically analyzed and simulated, and a packaged pressure sensor with the proposed sensing chip was tested under flexural and torsional modes of the microcantilever. The experimental results proved that the proposed sensor had preferable measuring performance under the torsional mode with the RSS (root sum square) accuracy of 0.21%FS in the working range of 10–560 kPa. The temperature compensation was presented to alleviate the temperature disturbance for the sensor, and the maximum deviation of the frequency was 59 ppm over the full pressure and the temperature range of 26–55 ℃. The proposed sensing chip is potentially a better choice for pressure sensors with measurement demand for immersive gas pressure.Graphical abstractAn immersive sensing chip with microcantilever was proposed to achieve immersive measurement for gas pressure based on sensing the gas density.Graphical abstract for this article
       
  • Real-time and hazard-free water quality monitoring based on microwave
           planar resonator sensor
    • Abstract: Publication date: Available online 9 November 2019Source: Sensors and Actuators A: PhysicalAuthor(s): Sevda Mohammadi, Anupama Vijaya Nadaraja, Deborah J. Roberts, Mohammad H. ZarifiThis manuscript presents the development of a microwave microfluidic sensor for monitoring organic contaminants in water. This method offers a contactless, non-intrusive, and real-time monitoring system. The sensor is comprised of a compact double-ring resonator integrated with a 3D-printed microfluidic channel, operating at 4.5∼4.6 GHz with a quality factor of 120. The channel configuration on the resonator ensures maximum interaction between the electromagnetic field and the liquid sample and provides high sensitivity and resolution. The developed sensor was used to monitor organics (glucose, acetate and glucose-acetate mix) and the chemical oxygen demand (COD) standard (potassium hydrogen phthalate) in concentrations ranging from 50 to 800 mg/L as COD. The feasibility, reproducibility, and accuracy of the sensing platform was further validated by analyzing the S21 characteristic of the sensor. A monotonic decrease in the resonant amplitude of S21 was observed as the concentration of organics increased, with the sensitivity of 0.603 dB/COD [g/L], 0.087 dB/COD [g/L], 0.099 dB/COD [g/L] and 0.077 dB/COD [g/L] for potassium hydrogen phthalate, sodium acetate, glucose, and a glucose- acetate mixture, respectively. The findings support the capability of the microwave microfluidic sensor to detect dielectric properties variation associated with a minimum concentration of 17 mg/L glucose in water in real time. The response of the sensor was compared with conventional COD measurements using potassium dichromate digestion to compare the efficiency of the developed sensor with the spectrophotometric method to measure COD.Graphical abstractGraphical abstract for this article
       
  • Pressure sensor for hostile media
    • Abstract: Publication date: Available online 9 November 2019Source: Sensors and Actuators A: PhysicalAuthor(s): G. Moagăr-Poladian, C. Tibeică, V. Georgescu, F.M. Chilom, V. Moagăr-Poladian, O. TutunaruMeasuring pressure in hostile media such as toxic, flammable, explosive, biologically contaminated, corrosive ones is of paramount importance. Many commercially available pressure sensors fail to measure in such conditions because of physico-chemical degradation. It is the aim of this paper to present a pressure sensor that is able to withstand all such harsh conditions. The idea is based on the “More-than-Package” concept developed previously. Concept, simulation and characterization of such a device are described. The pressure signal is sent to outer environment without any electrical interconnects crossing the separation wall between the hostile medium and the outer environment. A magnetic field is used for transferring the displacement of the inner sensing membrane element situated in the harsh environment to the external part containing the magnetic sensing unit.Graphical abstractGraphical abstract for this article
       
  • One-step fabrication of SnO2 porous nanofiber gas sensors for sub-ppm H2S
           detection
    • Abstract: Publication date: Available online 9 November 2019Source: Sensors and Actuators A: PhysicalAuthor(s): Phan Hong Phuoc, Chu Manh Hung, Nguyen Van Toan, Nguyen Van Duy, Nguyen Duc Hoa, Nguyen Van HieuSnO2 porous nanofibers (NFs) were deposited on-chip by using a facile electrospinning method followed by heat treatment at 600 °C and used to detect H2S concentrations at sub-parts per million level. Morphological, compositional, crystal, and atomic structural properties of the as-spun and calcined SnO2 NFs were investigated by field emission electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy, respectively. SnO2 porous NFs with an average diameter of 150 nm and consisting of many nanograins were successfully fabricated by on-chip electrospinning. The NFs were crystallized as the tetragonal structure of SnO2 with an average crystallite size and dislocation density of approximately 13.5 nm and 5.615 × 1015 lines/m2, respectively. The sensing characteristics of the SnO2 NF sensors were tested with 0.1–1 ppm H2S from 150 °C to 450 °C. The sensor achieved the optimal performance at 350 °C and exhibited gas response of 15.2 with fast response/recovery times of 15 s/230 s. The H2S gas sensing mechanisms of the SnO2 porous NF sensors were due to the modulation of the resistance along the surface depletion layer and the grain boundaries. The fabricated sensor also indicated a good selectivity to H2S, short-term stability, and the low detection limit of 1.6 ppb. The influence of humidity on the sensor’s performance in a low temperature range is also discussed.Graphical abstractSnO2 NF sensors were fabricated on-chip using the electrospinning method as illustrate in the inset. Dynamic responses of the SnO2 NF sensors at 350 °C to various gases indicate a high sensitivity of the fabricated sensor to H2S gas with a good selectivty.Graphical abstract for this article
       
  • Neural Network Based Hysteresis Compensation of Piezoelectric Stack
           Actuator Driven Active Control of Helicopter Vibration
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): De Meng, Pinqi Xia, Kai Lang, Edward C. Smith, Christopher D. RahnPiezoelectric Stack Actuators (PSAs) have become promising actuators for active control of helicopter fuselage vibration owing to their large output force, rapid response speed, wide working frequency and light weight. However, the hysteresis nonlinearity of PSA has negative influence on the performance of PSA-driven active vibration control. In this paper, to improve the performance of PSA-driven active control of helicopter vibration, the hysteresis nonlinear neural network and hysteresis compensation neural network of PSA have been established based on the Nonlinear Auto Regression eXogenous (NARX) model. The PSA's voltage-displacement relations under two-harmonic actuations were used for training the neural networks of hysteresis nonlinearity and hysteresis compensation. Then the compensation neural network for PSA's hysteresis was integrated into an active control system for helicopter vibration. The results of experimental investigation performed on a scale model of a representative helicopter fuselage floor structure indicate that the neural network based hysteresis compensation of PSA for active control of helicopter vibration can effectively reduce vibration of the scaled frame structure and can reduce more vibration than without compensation.Graphical Graphical abstract for this article
       
  • Highly-ordered assembly sheath layers of graphene coaxial fibers for
           high-performance wearable devices
    • Abstract: Publication date: Available online 13 January 2020Source: Sensors and Actuators A: PhysicalAuthor(s): Ping Li, Wen Wu, Jia Xu, Jianda Cao, Huanxia ZhangGraphene fibers (GF) have broad application prospects in the fields of supercapacitors, electrodes, stimuli response sensors, and smart wearables. However, previously reported graphene-based fibers generally have low toughness and poor stretchability, which may limit possible applications. Here, we prepared novel high-strength, -stretch, and -conductivity graphene fibers with dense and highly-ordered sheath layers and a porous core structure. This was prepared by an efficient one-step coaxial wet-spinning method, which forms the rapid traction of the core layers on the sheath layers by the speed difference of the former, which is faster than the latter. The fiber surface was also subjected to the scouring force of the coagulation bath when the spinning solution was sprayed out of the spinning hole. The tug-of-war effect of these two opposing forces reacts on the curved graphene sheets, which made the graphene layers gradually straighten out, so that the sheath is efficiently and orderly aligned. The elongation of the high-strength GF with a core-sheath structure was effectively improved by approximately double, which was much higher than the previous research results. Moreover, high strength was maintained, and electrical stability was observably increased due to the core-sheath structure of the fibers. Such fibers also exhibited very stable electrical resistance during radial compression and tension cycles. Furthermore, we demonstrated the application of the fibers in wearable flexible devices.Graphical abstractGraphical abstract for this article
       
  • LiNbO3 Nanocrystals for Tunable Ion Track Electronics and Gas
           Sensorics
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): K. Hoppe, W. Fahrner, A. Petrov, D. Fink, V. Hnatowicz, J. Vacik, D. Bork, P. HeitjansAbout 20 nm large LiNbO3 nanocrystals are produced by high-energy ball milling, and then suspended in water by surrounding them with amyl acetate ligands. The formed colloids are allowed to penetrate into etched swift heavy ion tracks in an oxide layer on silicon. After appropriate contacting, both a source-drain and a gate voltage are connected to the resulting electronic structure. Depending on the applied external voltages, the current-voltage characteristics shows peculiar properties, ranging from Ohmic-type via forward- or backward-rectifying types up to double-rectifying types, eventually with hysteresis showing up. These structures could become relevant to gas sensorics.Graphical abstractGraphical abstract for this article
       
  • Application of Piezoelectric Actuator to Simplified Haptic Feedback System
    • Abstract: Publication date: Available online 11 January 2020Source: Sensors and Actuators A: PhysicalAuthor(s): Chien-Hsien Yeh, Fong-Chin Su, Yan-Shen Shan, Marat Dosaev, Yury Selyutskiy, Irina Goryacheva, Ming-Shaung JuThe lack of haptic feedback in minimally invasive surgery results in the dependence on high-resolution images. This study used a simplified working abstraction of a haptic feedback system, including a master manipulator, a console table, a slave indenter, and a control algorithm to construct a scalable platform for a palpation device. A piezoelectric actuator was designed using finite element simulation, and was added to the master manipulator to produce thrust force against the user’s finger pressing. Button motion on the master manipulator was synchronized with the slave indenter's linear movement. If the indenter contacted an object, the loading was used to adjust the thrust force of the piezoelectric actuator in the console table. This function can be developed into a model of haptic perception, like palpating an object. Instead of a human operator, this study used a reciprocating mechanism to simulate finger pressing and tested the haptic feedback system under different contact conditions: two indentation speeds (0.84 mm/s, 4.2 mm/s) and two springs of different stiffness (214.6 N/m, 474.3 N/m). The results showed that our haptic feedback system allows estimating the stiffness of objects. Lower indentation speeds disclosed a clearer contact information. The piezoelectric actuator yielded better efficiency at the resonant frequency and smaller preload. A smaller friction force could increase the response speed. The response time of whole system was 0.36 s and the variation of the thrust force of one piezoelectric actuator was in a quite small range of 0.3 N. To improve the haptic feedback system, to integrate more actuators and to develop the embedded controller module were the potential solution.
       
  • Flexible and lead-free piezoelectric nanogenerator as self-powered sensor
           based on electrospinning BZT-BCT/P(VDF-TrFE) nanofibers
    • Abstract: Publication date: Available online 10 January 2020Source: Sensors and Actuators A: PhysicalAuthor(s): Jie Liu, Bin Yang, Lijun Lu, Xiaolin Wang, Xiuyan Li, Xiang Chen, Jingquan LiuABSTRACTRecently, the flexible and environmental-friendly piezoelectric generators have drawn much attentions due to the power-supplying apply applications of powering implantable and wearable devices. In this work, an environmental-friendly and flexible piezoelectric nanogenerator is proposed based on electrospinning nanofiber which is composed of 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (BZT-BCT) and polyvinylidene fluoride–trifluoroethylene P(VDF-TrFE). The as-prepared nanofiber mats with different amounts of doping of BZT-BCT nanoparticles varied from 0 wt% to 50 wt% are characterized by XRD and SEM. Based on the testing results, the nanofiber generator with 40% content of BZT-BCT exhibits the excellent output performance, which produces the output voltage as high as 13.01 V under cyclic tapping under 6 N and 10 Hz, which is mostly attributed from the doping of the BZT-BCT with high piezoelectric coefficient. The generator can be deployed as the self-powered sensor, which can measure the tensile and compressive deformation, the movement of different parts of body. Due to the advantages of flexibility and environmental kindness, this developed nanogenerator has great potential for wearable and implantable devices.Graphical abstractGraphical abstract for this article
       
  • Effect of cations on silicon anisotropic etching process in solutions
           containing TMAH and TMAH with tensioactive compounds
    • Abstract: Publication date: Available online 10 January 2020Source: Sensors and Actuators A: PhysicalAuthor(s): Irena ZubelAlmost everything has been written on silicon anisotropic etching in alkaline solutions, however, the difference between etching in pure KOH and TMAH as well as in these solutions containing tensioactive compounds has not been completely elucidated yet. This paper present the results of anisotropic etching of Si(100) and Si(110) in the solutions containing two etching agents, KOH and TMAH. Due to this it is possible to control the effect of concentration of each agent on the course of etching and clarify the effect of cation type (inorganic and organic) on the course of the process. The effect of TMA+ ions on etch rate of Si(100) has already been proven both during etching in pure TMAH as well as after addition of tensioactive compounds to this solution. It results in a change in anisotropy ratio (R(110)/R(100)) in TMAH containing solutions in comparison to solutions based on KOH. As the commonly used KOH concentrations (5 - 10 M) are larger than those of TMAH 25% (2.7 M), the concentration range of the studied TMAH solution has been extended to 50%. The paper describes the properties of those concentrated TMAH solutions, both pure and containing surfactants.Graphical abstractGraphical abstract for this article
       
  • Accurate and ultra-fast estimation of Brillouin frequency shift for
           distributed fiber sensors
    • Abstract: Publication date: Available online 10 January 2020Source: Sensors and Actuators A: PhysicalAuthor(s): Zhiniu Xu, Lijuan ZhaoThe original Lorentzian profile-based nonlinear least-squares problem for BFS estimation is converted to a linear least-squares one. Then, Brillouin frequency shift (BFS) can be readily calculated. The typical nonlinear least-squares Lorentzian, Gaussian, pseudo-Voigt and Voigt fits using Levenberg-Marquardt algorithm, the correlation-based algorithm and the proposed Lorentzian model-based linear least-squares fitting algorithm are used to estimate BFS of the measured Brillouin spectra with different values of SNR (signal-to-noise ratio) and frequency step. The results reveal that the proposed algorithm has similar accuracy with the nonlinear fits. However, the computation time of the typical nonlinear fits is 187.56∼11481.67 times as long as the proposed algorithm. The proposed algorithm can estimate BFS with less computational burden and higher accuracy than the correlation-based algorithm. If SNR is low, the frequency step should be set to a low value.Graphical abstractGraphical abstract for this article
       
  • High-performance UV-B detectors based on MnxZn1-xS thin films modified by
           bandgap engineering
    • Abstract: Publication date: Available online 10 January 2020Source: Sensors and Actuators A: PhysicalAuthor(s): Sema Ebrahimi, Benyamin Yarmand, Nima NaderiThe high-speed performance ultraviolet (UV) detectors were successfully fabricated based on the ternary MnxZn1-xS (0.2 ≤ x ≤ 0.4) thin films deposited by a simple spray pyrolysis method. The optoelectrical properties of the samples were modified by introducing the Mn impurities at high content to enhance the performance of UV detectors. Microstructural characteristics confirmed the well-incorporation of Mn2+ ions into the ZnS lattice having nanocrystalline nature with homogeneous surface and strong adherence to the substrates. The optical measurements revealed that at the higher Mn2+ concentration, the optical transmittance increased over 95% in the visible to near-infrared regions. Compared to the pure ZnS, the values of bandgap energy were found to blue-shift about 0.14 eV due to both quantum confinement and Burstein-Moss theories. Meanwhile, the Urbach energy decreased dramatically, leading to a considerable reduction of the electron-phonon interaction. The photoluminescence (PL) spectra revealed that the PL emission intensity was enhanced by introducing excess charge carriers through increasing the Mn2+ concentration, which can improve the generation of electron-hole pairs in alloys. The photoresponse characterization featured a tremendous photosensing and photoswitching for the fabricated UV detectors, in which an excellent UV-B responsivity and high visible rejection were observed for the devices. For the UV detector based on the Mn0.4Zn0.6S thin film, the current gain greatly improved over 4.5 times compared to the pure ZnS one. Likewise, the photoresponse speed of the samples was found to enhance over 80%, considerably.Graphical abstractGraphical abstract for this article
       
  • Micro/nano galvanic-coupled arrays for early and initial detection and
           prediction of dew condensation
    • Abstract: Publication date: Available online 10 January 2020Source: Sensors and Actuators A: PhysicalAuthor(s): Yusuke Kubota, Vijay Lakshmi Mishra, Tatsuya Ando, Yukihiro Sakamoto, Jin KawakitaDew condensation is ubiquitous but its consequences are mostly catastrophic for building, crops, electrical devices, aviation industry, air conditioning and pharmaceuticals, therefore detection and it’s monitoring at early or initial stage are critically required for its prevention which cannot be realized by current technologies. Moisture Sensor can detect a small water droplet and distinguish its size with high accuracy and quick response by the galvanic action upon water getting attached and bridging adjacent arrays composed of different metals. In this study, it was applied to detect dew condensation. The experimental results showed that Moisture Sensor could detect occurrence of dew condensation in initial and early stage with high accuracy in terms of dew point. Moreover, a stage prior to dew condensation, presumably adsorption of water molecules, was detected and distinguished quantitatively and accurately depending on the relative humidity below 100% around the arrays. Moisture Sensor also takes advantage of modifying its surface status such as wettability and temperature. It suggests that this sensing method can be an alternative to conventional hygrometer, especially in a high relative humidity region and expect prediction or premonition of dew condensation, which occurs on the actual target.Graphical abstractGraphical abstract for this article
       
  • All-metal oxide transparent photodetector for broad responses
    • Abstract: Publication date: Available online 10 January 2020Source: Sensors and Actuators A: PhysicalAuthor(s): Sohail Abbas, Joondong KimAll transparent photodetector is realized by metal oxide heterojuction of p-NiO and n-TiO2. This transparent photodetector is self-operation by photovoltaic effect without an external bias. By forming the built-in potential between two metal oxide layers, spontaneously established electric field controls the carrier collections. Silver nanowires (AgNWs) were applied as a top contact and fluorine-doped tin-oxide (FTO) layer worked as a back contact. The relatively high transparency (∼44%) was secured for the photodetector of AgNWs/NiO/TiO2/FTO/Glass. To realize high-performing and broad wavelength photodetection, energy band tuning was performed by N2-doping process. The N2-treated transparent photodtector effectively detect UV, blue and green light with a high photocurrent of 558, 171 and 66 μA, respectively. Moreover, the photodetector achieved excellent responsivity (136 mA/W), detectivity (1.11 × 109 Jones), noise-equivalent power (9.2 × 10-10 W. Hz-1/2) and linear-dynamic-range (34 dB). The functional doping of wide-bandgap metal-oxides modifies band energies, which suggests the high possibility of broad photodetection and improved photoelectric devices, including photovoltaics.Graphical Graphical abstract for this article
       
  • Thermopower Determination using Pyrolytic Graphite and Aluminum
           Thermocouple
    • Abstract: Publication date: Available online 9 January 2020Source: Sensors and Actuators A: PhysicalAuthor(s): Abdul-Sommed Hadi, Bryce E. HillHigh temperature processes of metal casting require the use of specialized instruments for measurements. A thermocouple is one such instrument frequently used due to its many advantages of low cost, high accuracy and ease of access. With aluminum being one of the most widely used metals in the metallurgical and automobile industries, there is the need for a custom thermocouple for use in these sectors. In this research work, a custom thermocouple designed from pyrolytic graphite (PG) and aluminum is developed. The research effort is then concentrated on determining the Seebeck coefficient of our instrument. A near-linear response was obtained for our instrument on a voltage-temperature graph. A thermopower/Seebeck coefficient of 14.4 μV/℃ was obtained for the heating experiment while the cooling experiment produced a sensitivity of 14.7 μV/℃.Graphical abstractGraphical abstract for this article
       
  • VOC gas Sensor based on Hollow Cubic Assembled Nanocrystal Zn2SnO4 for
           Breath Analysis
    • Abstract: Publication date: Available online 8 January 2020Source: Sensors and Actuators A: PhysicalAuthor(s): Nguyen Hong Hanh, Lai Van Duy, Chu Manh Hung, Nguyen Van Duy, Young-Woo Heo, Nguyen Van Hieu, Nguyen Duc HoaHollow cubic assembled nanocrystal Zn2SnO4 was synthesized via one-step hydrothermal method for VOC gas sensing applications. The obtained Zn2SnO4 materials had a uniformly hollow cubic structure with an average size of approximately 1 µm and a wall thickness of about 150 nm formed from nanocrystals of around 14 nm. The X-ray absorption near-edge structure results showed no structural disorder and/or lattice damage around the Zn-absorbing atoms and the Zn oxidation state of 2+ in the host lattice of the hollow cubic Zn2SnO4. The gas sensing characteristics of the prepared Zn2SnO4 material were tested to C3H6O, C2H5OH, CH3OH, NH3, H2, and CO at 350 °C–450 °C and results showed that the sensors exhibited a good response to acetone and ethanol gases. The highest response values were 47.80 for 125 ppm of acetone and 7.52 for 10 ppm of ethanol at 450 °C. The Zn2SnO4 hollow cubic sensor demonstrated high sensitivity and selectivity to acetone with good stability and a detection limit of 175 ppb. The VOC sensing mechanism of the hollow cubic Zn2SnO4-based sensor was also discussed. The findings indicated that hollow cubic Zn2SnO4 is a promising material for use in excellent VOC gas sensing application towards breath analysis.Graphical abstractGraphical abstract for this article
       
  • Experimental Investigation of Strain Sensitivity for Surface Bonded Fibre
           Optic Sensors
    • Abstract: Publication date: Available online 8 January 2020Source: Sensors and Actuators A: PhysicalAuthor(s): P. Motwani, N. Perogamvros, S. Taylor, M. Sonebi, A. Laskar, A. MurphyThe strain sensitivity coefficient for a surface-mounted fibre optic sensor is strongly affected by the type of adhesive material used for its installation. In the present study, appropriate strain correction factors have been investigated to modify the strain sensitivity coefficient for surface mounted fibre Bragg gratings to achieve accurate strain data. The experimental study adopts a fibre optic sensor (FOS) mounted on a carbon fibre reinforced polyphenylene sulphide specimen using two adhesive types, i.e. a cyanoacrylate and an epoxy-resin. For comparison purposes strain data was also captured using strain gauge, contact extensometer and digital image correlation instrumentation. The experiments reveal that the predicted correction factors vary considerably with the adhesive material used for the mounting of the FOS. Further analysis demonstrates that a 37% deviation in the value of the correction factor results in a 27% variation in the strain output. In addition, the microscopic image analysis confirmed that the thickness of the adhesive layer between FOS and the substrate affects the strain sensitivity of FOS and plays a crucial role in transmitting the deformation of the host material to the sensing element.Graphical abstractGraphical abstract for this article
       
  • Electrospun polyamide-6 nanofiber for hierarchically structured and
           multi-responsive actuator
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): Libo Huang, Xiaoxu Xie, Hong Huang, Jing Zhu, Junrong Yu, Yan Wang, Zuming HuActuators that can respond mechanically to external stimulus have attracted great interests because of their great potential in applications of artificial muscle, soft robot, sensor, power generator, and so on. However, the creation of low-cost and multi-responsive actuators from conventional materials is still challenging. Herein, we demonstrate a new kind of hierarchically structured and multi-responsive actuator by twisting electrospun polyamide-6 into coiled yarn (CPY). Due to the presence of microscale and nanoscale cavities, the CPY can reversibly rotate in response to various organic solvents, and the rotation speed is depended on the type of solvent. Capillary force driven shrinkage is suggested as the actuating mechanism of our CPY, which is different from all previously reported coiled yarns. The high coefficient of thermal expansion of polyamide-6 also makes the CPY heat responsive, as the CPY shows contraction upon heating due to the volume expansion induced untwisting. In addition, NIR light and water responsiveness can be further inserted into the CPY by modifying the non-woven with polydopamine prior to twisting as demonstrated here.Graphical abstractGraphical abstract for this article
       
  • Reliable Tin dioxide based nanowire networks as ultraviolet solar
           radiation sensors
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): Estácio P. de Araújo, Adryelle N. Arantes, Ivani M. Costa, Adenilson J. ChiquitoNowadays, 1D material SnO2 (n-type) have been standing out, demonstrating their potential application in ultraviolet (UV) radiation and chemical sensing, as in optical communication, safety devices and biological fields. In this work, we discuss the characteristics of an UV sensor device built in a metal-semiconductor-metal (MSM) architecture using a SnO2 nanowire network as the sensing element. SEM and XRD techniques were used to characterize the device, revealing uniform structures and excellent crystallization, respectively. Photoresponse of the nanowire network was obtained under three different sources of radiation: one in the visible region (White Light- 9.5 mW/cm2), another in the UV region (UV Lamp – 2 mW/cm2) and finally, using direct solar radiation (Sun Light – 78.6 mW/cm2). The area illuminated of device was 7.8 × 10−7 m2.When exposed to the sources containing UV wavelength, we obtained a current on/off ratio of the order of 104, rise time up to 2.8 s and multiple decay times from 1 s to 100 s. These results enable the design of a sensor based on nanowire networks presenting high sensibility and selectivity, particularly in outdoor measurements and also an optimized regime of operation.Graphical abstractGraphical abstract for this article
       
  • Fabrication of flexible piezoresistive sensors based on RTV-silicone and
           milled carbon fibers and the temperature´s effect on their electric
           resistance
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): Carlos-Manuel Sánchez-González, Juan-Felipe Soriano-Peña, José-Carlos Rubio-Avalos, J.-Jesús Pacheco-IbarraFlexible robotics and smart wearable technologies are under intensive research due to their potential applications. Flexible sensors that are an essential part of these systems are mainly made of a soft polymer matrix and an electric conductive reinforcement. However, when a flexible sensor is heated or an electric current is applied a joule heating effect is produced rising the material´s temperature, and since soft polymers are temperature-sensitive there is a change in their physical dimensions, giving as a result, a dramatic change in their electric properties. This work contributes to a better understanding of the temperature´s effect on the piezoresistive properties of these sensors, (i.e.) the electric resistance of some sensors changed from ohms at room temperature to Mega-ohms at 80 °C, these change were possible due to an excellent thermal conductivity and heat distribution of the flexible resultant composites, as well as, the physical expansion of the polymer matrix reducing the milled carbon fibers´ interconnectivity and increasing the potential barrier between them.Graphical abstractGraphical abstract for this article
       
  • Research on the spreading characteristics of biodegradable ethyl
           cyanoacrylate droplet of a piezoelectric inkjet
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): Kai Li, Weishan Chen, Junkao Liu, Hengyu Li, Naiming Qi, Yingxiang LiuPiezoelectric inkjet has been widely applied in printing field thanks to its advantages of ejecting small droplet precisely. The method of printing biodegradable structure for tissue support or connection by piezoelectric inkjet is proposed in this work, which will contribute to wound repair in vivo and avoid secondary trauma caused by removing non-biodegradable support. A piezoelectric inkjet with simple structure is designed for printing biodegradable ethyl cyanoacrylate solution. Basic studies of printing biodegradable ethyl cyanoacrylate structure are carried out. The spreading characteristics of ethyl cyanoacrylates droplets before solidification under different conditions are studied by simulation analyses, and the methods for stabilizing the spreading performance and avoiding failure spreading are obtained. The spreading characteristics of the droplets before and after solidification under different conditions are analyzed by experiments, and the corresponding shrinkage ratios are obtained. Based on the obtained shrinkage ratios (between 70 % and 75 % when spreading without satellite droplets) and spreading dimensions before solidification (obtained by simulation analyses), the final formed size of the ethyl cyanoacrylate droplet can be estimated to determine the appropriate printing distance in continuous printing. A simple structure is printed by the piezoelectric inkjet to verify the feasibility of the proposed method of the printing ethyl cyanoacrylate biodegradable structure for medical care.Graphical abstractGraphical abstract for this article
       
  • A novel rhombic-shaped paper-based triboelectric nanogenerator for
           harvesting energy from environmental vibration
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): He Zhang, Huagang Wang, Jiwei Zhang, Zhicheng Zhang, Ying Yu, Jikui Luo, Shurong DongTriboelectric nanogenerator (TENG) as a promising energy harvesting technology attracts much attention in recent years. Among others, the contact mode TENG is often given priority by virtue of its reliable robustness and high energy conversion efficiency. However, in most cases, the contact-mode TENG is only suitable for collecting energy from pressure-induced incentives because it requires a compression forces to drive. Here, we propose a rhombic-shaped paper-based triboelectric nanogenerator (RP-TENG) that may operate effectively under tensile conditions together with an enhanced contact force between the tribo-pair induced by the design of pressurizing braces. Mechanical tests were carried out to investigate the output performance of the RP-TENG under the activation of various applied forces. An integrated RP-TENG with four tribo-pairs were fabricated for optimizing the output performance. The novel design facilitates the device to achieve higher energy conversion efficiency and also expand its application circumstances. A theoretical model is developed to establish the correlation between the output voltage of the RP-TENG and the geometric characteristics as well as external excitations. The results suggest an effective strategy of using paper-based rhombic-shape design to enhance contact-mode TENGs and may serve as a guideline for structural and circuit design of this novel TENG devices.Graphical abstractGraphical abstract for this article
       
  • A chip-scale frequency down-conversion realized by MEMS-based filter and
           local oscillator
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): Jyoti Satija, Sukomal Dey, Shashwat Bhattacharya, Gayathri Pillai, Sheng-Shian LiA wide-width clamped-clamped beam (CC-beam) resonator and a filter realized using mechanically-coupled resonator tanks have been extensively characterized to attain mixler (i.e., mixer-filter) functionality for a chip-scale frequency translation. Such a resonator has been driven into the nonlinear regime to explore its effect on the mixler operation as well as to obtain the best phase noise performance using the phase-feedback method. The proposed electrostatically transduced mixler operates by utilizing the local oscillator (LO) signal generated from the resonator itself, thus eliminating the need of a function generator or an external quartz crystal oscillator. This technique implemented with all the components on the same silicon substrate shows great potential for miniaturization in wireless communication while achieving 14.4 dB overall mixler loss.Graphical abstractGraphical abstract for this article
       
  • Resonator-based M/NEMS logic devices: Review of recent advances
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): Saad Ilyas, Mohammad I. YounisAs transistors are reaching their fundamental limits in terms of power consumption, miniaturization, and heat generation, there is an imminent need to develop alternate computing technologies. One such an alternative is through micro/nanoelectromechanical systems (M/NEMS) that focuses on ultra-low energy consumption. Computing based on static MEMS switches has been proposed, however these suffer from reliability issues due to contact and stiction. Recently, logic devices based on electro mechanically excited vibrating structures, resonators, have emerged as a potential solution that overcomes these issues. This paper reviews the recent advancements of resonator-based M/NEMS logic devices. First, pioneering works in the field are surveyed. Then, logic devices based on frequency tuning are discussed. Next, cascadability of such logic devices is demonstrated. Finally, a discussion about the challenges of such technology and future prospects is presented.Graphical abstractGraphical abstract for this article
       
  • Influence of the AlN/Pt-ratio on the electro-mechanical properties of
           multilayered AlN/Pt thin film strain gauges at high temperatures
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): P. Schmid, F. Triendl, C. Zarfl, S. Schwarz, W. Artner, M. Schneider, U. SchmidIn this work, the impact of the AlN/Pt ratio on the strain-sensitive properties of multilayered AlN/Pt thin films is investigated. These thin film systems consisting of 10 bi-layers of AlN and Pt each with a thickness of 3 nm AlN and 7 nm Pt or 5 nm AlN and 5 nm Pt are fabricated, evaluated and compared to those realized with a sequence of 7 nm AlN and 3 nm Pt thin bi-layers. The thin film systems are sputter-deposited on oxidized silicon wafers or sapphire substrates. The influence of different annealing steps at 900 °C up to 24 h in Argon (Ar) atmosphere on the electrical film resistivity and the temperature coefficient of the electrical resistance (TCR) is investigated for these different multilayers using Van-der-Pauw measurements up to 330 °C in air. Furthermore, the impact of the AlN/Pt-ratio on the gauge factor of the thermally stabilized multilayers is determined using a purpose-built measurement setup up to 500 °C in air. Transmission electron microscopy and X-ray diffraction analyses are utilized to examine the microstructure and the crystallographic phase composition of the multilayers before and after thermal loading. Annealing the different multilayers at 900 °C leads to diffusion effects between the AlN and Pt thin films and recrystallizations processes in the Pt sublayers depending on the individual sublayer thickness values. After thermal pre-conditioning at 900 °C for 1 h in Ar the samples were stable even in air up to 500 °C. Finally, it is shown that the TCR as well as the gauge factor of an AlN/Pt multilayer can be tuned through the AlN/Pt-ratio. The highest gauge factor with a value of 4.7 (±0.3) at room temperature is achieved with a multilayer consisting of 5 nm AlN and 5 nm Pt (pure Pt thin film on Cr adhesion promotor: 3.2), while the lowest linear TCR with a value of α = 7.4 ∙ 10−4 K-1 is measured for multilayers with 7 nm AlN and 3 nm Pt sublayers (pure Pt thin film on Cr adhesion promotor: 3.66 ∙ 10-3 K-1).Graphical abstractGraphical abstract for this article
       
  • Low-dose X-ray sensing nature of nanostructured Zn(Cu)O thick films
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): R.R. Karthieka, T. Subashini, Lakshmi Devi. S, T. PrakashNanostructured Zn(Cu)O in different morphologies were prepared by simple thermal decomposition of respective acetate precursors in three different processing temperatures (350 °C, 550 °C and 750 °C) and characterized using various techniques. Further, the X-ray excited photocurrent studies were carried out for all the three sample′s thick films coated on the top of patterned interdigitated electrode. This measurement was carried out at room temperature under the illumination of X-ray at 3.2 s using an intra-oral X-ray machine. The measured electrical current was applied to calculate percentage of X-ray sensitivity for nanostructured Zn(Cu)O samples obtained at 350 °C, 550 °C and 750 °C were found to be 1.43, 1.04 and 0.69 nC mGy−1  cm−3 respectively. These obtained experimental findings explore the role of crystallite size on low-dose X-ray sensing nature of nanostructured Zn(Cu)O. A suitable mechanism was proposed to explain the sensing nature of nanostructured Zn(Cu)O.Graphical abstractGraphical abstract for this article
       
  • Microfluidic random number generator driven by water-head pressure and
           human finger push
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): Korakot Boonyaphon, Shuichi Takayama, Sung-Jin KimRandom number (RN) generators are indispensable in scientific simulations, cryptography, and games. Generation of high-quality RNs with unpredictable and indecipherable characteristics, however, has generally required complex and sophisticated systems. This paper describes a microfluidic RN generator that relies only on a constant water-head pressure and the push action of a human. The RN generator is comprised of three units: an astable oscillator, a bistable switch, and a push-button membrane. A constant pressure fluid flow is converted to pulsatile, high and low pressure flows by the astable unit. At the moment of a random push and release of the membrane unit, the bistable unit retains and displays either a high or low pressure state resulting in generation of a random bit. Repeated operation of the random bit generator produces series of RNs. Taking advantage of the human interactions involved, the microfluidic RN generators were developed into two games: (i) a single RN generator that functions as a coin flip game, and (ii) a quadruple RN generator that substitutes for four four-sided pyramid-shaped die and help play the Royal Game of Ur, commonly referred to as the world’s oldest board game. Importantly, a US National Institute of Standards and Technology (NIST) test of the RNs generated by the RN generator confirmed high quality randomness with unpredictability and unrepeatability ensuring that the games are fair.Graphical abstractGraphical abstract for this article
       
  • Novel layered GO/Mg(OH)2 nanocomposites for detection of Cd and
           Pb ions
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): Payel Maiti, Pradip Sekhar Das, Jiten Ghosh, Anoop Kumar MukhopadhyayHere we report the efficacy of the photoluminescence (PL) spectroscopy for novel detection of as low as 0.0001 to as high as 0.01 ppm of Cd2+ and Pb2+ ions in simulated wastewater solution. The solution comprises of 20 mg of layered graphene oxide (GO)-Mg(OH)2 nanocomposite (LGOMHNC) powders in 100 ml of DI water. The LGOMHNC powders, synthesized by facile wet chemical route, are characterized by XRD, FESEM, TEM, FTIR, Raman spectroscopy, TGA-DTA, XPS and especially, the PL spectroscopy techniques. After adsorption of Cd2+ and Pb2+ ions, the novel LGOMHNC powders exhibit significant enhancement of the corresponding PL intensities as compared to those of the as-synthesized LGOMHNC powders. These results suggest that PL spectroscopy can indeed emerge as a very important tool for detection of even 0.0001 ppm of Cd2+ and Pb2+ ions in simulated wastewater. In addition, the novel LGOMHNC powders developed in the present work can have huge application potential in futuristic, optical sensor-based detection of the toxic, heavy metal ions like Cd2+ and Pb2+.Graphical abstractGraphical abstract for this article
       
  • AlGaN/GaN HEMT based sensor and system for polar liquid detection
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): Nidhi Chaturvedi, Kuldip Singh, Pharyanshu Kachhawa, Richard Lossy, Shivanshu Mishra, Ashok Chauhan, Dheeraj K. Kharbanda, Amber Kumar Jain, Rajiv Ranjan Thakur, Devanshu Saxena, Pramod K. Khanna, Joachim WuerflIn this paper, a GaN-high electron mobility transistor (HEMT) based sensor is designed, fabricated and characterized for polar liquid sensing. The fabricated HEMT sensor chip is packaged by using low temperature co-fired ceramic (LTCC) technique. The sensor shows a typical drain current of 21.2 mA at 3.3 V. The fabricated sensor shows a percentage change of 1.78%, 2.18% and 6.3% in drain current for mercury chloride, copper chloride and sodium chloride respectively with respect to the drain current of pure water. The readout circuit shows a change of 0.15, 0.20 and 0.34 mA in drain current for acetone, water and methanol respectively and ensures the detection of different polar liquids. Due to the novel inter-digital structure, the sensor shows a sensitivity of 5.98 mA/mm/Debye at a drain voltage of 3.3 V. Sensing mainly depends on the dipole moment because the change in the dipole moment of the liquid causes a change in surface potential at the gate sensing area. This paper gives a theoretical and practical perspective on polar liquid detection using both, the sensor and system.Graphical abstractGraphical abstract for this article
       
  • Microhole-pair hollow core fiber Fabry–Perot interferometer
           micromachining by a femtosecond laser
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): Cheng-Ling Lee, Yang Lu, Chien-Hsing Chen, Chao-Tsung MaAbstractThis study presents a sensitive and high-response microhole-pair (MP) hollow-core fiber (HCF) Fabry–Perot (FP) interferometer (MPHCFFPI) by microdrilling two holes symmetrically on the sidewall of the HCF via a femtosecond laser micromachining technique. The dimension of FP microcavity in the MPHCFFPI is length of the HCF. Only 0.005 s is needed to completely fill the HCF cavity with alcohol via the capillary action of the MP. The MPHCFFPI is developed to measure the thermo-optic coefficients (TOCs) and refractive indices (RIs) of liquids to investigate its effectiveness and accuracy. The TOCs of the deionized water, ethanol, and acetone are accurately determined as −1.076×10−4, −3.11×10−4, and −4.28×10−4 °C−1, respectively. The measured RIs of liquids ranging from 1.3 to 1.6 also highlight that the proposed fiber sensor can achieve higher RI than the silica fibers.
       
  • Piezoelectromagnetic synergy design and performance analysis for wind
           galloping energy harvester
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): Ting Tan, Xinyu Hu, Zhimiao Yan, Yajian Zou, Wenming ZhangAbstractTo improve the performance of the wind galloping energy harvester, the piezoelectromagnetic synergy design is proposed. Hamilton's principle and Euler–Bernoulli beam assumptions, quasi-steady hypothesis, Gauss law and Faraday's law are adopted to establish an electromechanical coupled distributed parameter model for the hybrid energy harvesting system. Using the harmonic balance method, the approximate analytical solutions of the dynamic response and electric output are derived. Wind tunnel experiments validate the nonlinear results of the proposed model including the Hopf bifurcation and unsteady response. The load resistances are optimized via finding the extreme of the power binary function. For the wind speed smaller than the critical wind speed, the piezoelectric module works with switched-off electromagnetic module. For the wind speed larger than the critical wind speed, piezoelectric and electromagnetic modules work concurrently to realize the synergistic effect. The piezoelectromagnetic galloping energy harvester is demonstrated to be superior than the piezoelectric galloping energy harvester and the electromagnetic energy harvester for higher harvested power from smaller galloping oscillations.
       
  • High resolution measurement of refractive index with resistance to
           temperature crosstalk through an all fiber MZI-PMF structure
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): Ruiling Qi, Li Xia, Nishan Wu, Zhao Yang, Tiantian RuanA simple cascaded structure composed of all-fiber Mach-Zehnder interferometer (MZI) and polarization-maintaining fiber (PMF) is proposed and experimentally demonstrated for simultaneous refractive index (RI) and temperature measurement. By splicing a section of thin no-core fiber (TNCF) between two conventional no-core fibers (NCFs) with large lateral offset, a part of the light in the MZI structure can interact directly with the external environment to obtain a high RI sensitivity. A Panda-type PMF is cascaded with the MZI to eliminate temperature crosstalk in the RI measurement. The experimental results show that the RI sensitivity of MZI is as high as −13862 nm/RIU, and the temperature sensitivities of MZI and PMF are −0.4 nm/℃ and 1.47 nm/℃, respectively. With the help of a sensitivity matrix, the change of RI and temperature can finally be demodulated. The RI and temperature resolutions of the cascaded structure can achieve 1.83 × 10−6 RIU and 0.014 ℃ respectively, to the best of our knowledge, which are the highest among all fiber structures without special materials coating or filling for simultaneous measurement. This structure presents outstanding advantages of easy fabrication, low cost and less sample consumption, which has great potential for integrated biochemical analysis systems.Graphical abstractA simple cascaded structure composed of all-fiber Mach-Zehnder interferometer (MZI) and polarization-maintaining fiber (PMF) is proposed and experimentally demonstrated for high resolution refractive index measurement with resistance to temperature crosstalk.Graphical abstract for this article
       
  • Research on double-outlet valveless piezoelectric pump with fluid guiding
           body
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): Bangcheng Zhang, Yong Huang, Lipeng He, Quanwen Xu, Guangming ChengAbstractIn order to address the performance limitations of valveless piezoelectric pumps caused by backflow, a double-outlet valveless piezoelectric pump with a fluid guiding body to weaken liquid backflow energy has been designed. The pump chamber introduces a streamlined fluid guiding body incorporated with a double-outlet structure. When the piezoelectric pump absorbs water, the liquid from the outlet violently collides at the tail end of the fluid guiding body. The liquid then flows through the two ports and collides at the chamber, thereby attenuating the backflow liquid energy. The mechanism alleviates the problem of backflow in valveless piezoelectric pumps. This work examines the relationship between the main structural parameters of double-outlet valveless piezoelectric pumps with a fluid guiding body and the resulting energy loss of the backflow liquid. The effectiveness of the dual-outlet structure to suppress backflow of valveless piezoelectric pumps is analyzed using a finite element method, and the optimal pipe distance and tail distance parameters of the piezoelectric pump are predicted through multiple sets of simulations. Finally, a series of prototypes within the parameters of this study were produced, and experiments were performed. The test results show that the energy loss of the backflow liquid affects the output performance of the piezoelectric pump. In the parameter range investigated here, increasing the energy loss of the backflow liquid improves the performance of the valveless piezoelectric pump. The piezoelectric pump was designed to have a flow rate of 167.8 mL/min with a Piezoelectric actuator diameter of 35 mm at an applied voltage of 210 V at a frequency of 49 Hz.
       
  • A review of optical interferometry techniques for VOC detection
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): Sulaiman Khan, Stéphane Le Calvé, David NewportExposure to volatile organic compounds (VOCs) is widely associated with adverse health effects. Detection and monitoring of VOCs are important for maintaining safe and healthy industrial and domestic environments. Interferometry is a highly-sensitive optical measurement technique that has been widely applied to a vast range of physical parameters from the speed of light to temperature and has also been used to detect VOCs at the sub-ppm range. Owing to the vast range of interferometer arrangements and processing techniques, this review assesses the different approaches adopted in detecting VOCs. Different interferometry arrangements including the Fabry-Perot interferometry, Sagnac interferometry and Mach-Zehnder interferometry are reviewed for VOC detection, including the different sensing films and materials employed. We present the basis of each technique, applications and limitations. The different interferometry techniques are summarized by comparing the sensitivity, limit of detection, linearity, response time and the challenges of current interferometry techniques. Lastly, prospects to realize a miniaturized, high-sensitive and multiplex interferometric sensors based on the recent technology are suggested.Graphical abstractGraphical abstract for this article
       
  • A novel XYZ micro/nano positioner with an amplifier based on L-shape
           levers and half-bridge structure
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): Yanling Tian, Yue Ma, Fujun Wang, Kangkang Lu, Dawei ZhangThis paper presents the design, modeling, and experimental validation of a novel XYZ micro/nano positioner driven by piezoelectric actuator (PEA). To achieve a large motion stroke, compact structure and good decoupling performance, a novel displacement amplifier including L-shape levers and half-bridge (LSLHB) is proposed. By utilizing a concave input mechanism for location restriction between PEA and flexible mechanism, the motion coupling caused by the inconsistent central axes of the PEA and input mechanism is eliminated. The XYZ micro/nano positioner mainly consists of a parallel XY stage and a Z stage nested on the XY stage. The XY stage is constructed with four LSLHB amplifiers which are orthogonally arranged to realize X- and Y- axis motion and kinematic decoupling. The characteristics of the positioner are studied by analytical modeling and finite element analysis. The XYZ micro/nano positioner is manufactured by wire electrical discharge machining, and the performance of the positioner is evaluated through experimental tests. The results show that the stage can implement three degree-of-freedom translational motion with a workspace of 128.1 μm×131.3 μm×17.9 μm, and the coupling errors in the non-working direction is less than 1.56 % of the motion stroke, and motion resolution is 8 nm.Graphical abstractGraphical abstract for this article
       
  • Active flow control for supersonic aircraft: A novel hybrid synthetic jet
           actuator
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): Jinfeng Li, Xiaobing ZhangIn order to improve the performance of traditional synthetic jet actuators in active flow control for supersonic aircraft, a novel millimeter-scale hybrid synthetic jet actuator (HSJA) is proposed in this paper. It provides additional power for the jet spout stage and gas refresh stage by adding a piezo-driven diaphragm at the bottom of the plasma synthetic jet actuator (PSJA). On the one hand, the problem of the low jet velocity of the piezo-driven synthetic jet actuator (PDSJA) could be avoided due to the heating and pressurization of gas by arc discharge. On the other hand, more external gas would be refilled during the gas refresh stage due to the restoration of the piezo-driven diaphragm compared with the plasma synthetic jet actuator. In an attempt to optimize the structure of the novel hybrid synthetic jet actuator, the flow field of the actuator is numerically simulated. The results show that the peak velocity of synthetic jet and the gas refilled rate are both increased compared with the plasma synthetic jet actuator. The effectiveness of the proposed hybrid synthetic jet actuator is verified.Graphical abstractGraphical abstract for this article
       
  • Large-bandwidth piezoelectric energy harvesting with frequency-tuning
           synchronized electric charge extraction
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): A. Brenes, A. Morel, D. Gibus, C.-S. Yoo, P. Gasnier, E. Lefeuvre, A. BadelThis paper reports, for the first time, experimental evidence of the effectiveness of the frequency-tuning synchronized electrical charge extraction technique (FTSECE) with a strongly-coupled generator. The ratio between the system bandwidth (7 Hz) and the natural bandwidth of the transducer (0.688 Hz) is 1017 %, surpassing previous demonstrations of synchronized charge extraction methods by a large extent. We prove that the bandwidth of the FTSECE system is only limited by the unideal characteristics of the circuit components and generator. This is a major advantage of FTSECE as opposed to other competitive methods where the bandwidth is intrinsically mathematically limited, even in the hypothetical presence of ideal components. We also propose a new circuit for the implementation of FTSECE, which allows the piezoelectric generator to be connected to the same ground as the control circuit. Our experimental setup based on the combination of a strongly-coupled piezoelectric generator and a FTSECE architecture allows operation at a maximum power plateau on a +/-3.5 % interval around the resonance frequency. The resulting full width at half maximum (FWHM) is +/-10 % around the resonance frequency, which corresponds to +200 % compared to most up-to-date architectures designed for bandwidth enhancement, with the advantage of suppressing local minima in the power responses.Graphical abstractGraphical abstract for this article
       
  • Enzyme-triggered inner filter effect on the fluorescence of gold
           nanoclusters for ratiometric detection of mercury(II) ions via a
           dual-signal responsive logic
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): Wenjia Li, Dong Liu, Xiaoya Bi, Tianyan YouHerein a novel ratiometric fluorescence strategy based on enzyme-triggered inner filter effect (IFE) was described to sensitively detect mercury ions (Hg2+) for the first time by using l-proline-protected gold nanoclusters (AuNCs) and 2,3-diaminophenazine (DAP) as IFE fluorophore and absorber. The IFE was derived from the overlap between the emission band of AuNCs and absorption band of DAP and confirmed by fluorescence lifetime decay tests. Based on IFE principle and ratiometric strategy, laccase (LACC)-catalyzed o-phenylenediamine (OPD) oxidation was utilized to produce DAP, whereas the activity of LACC can be monitored by Hg2+. In this way, the existence of Hg2+ could depress the emission of DAP while restore that of AuNCs, achieving the dual signal response of Hg2+, and their emission intensity ratio was dependent on the concentration of Hg2+. Under the optimized detection conditions, the linear range for Hg2+ determination was from 0.8 to 35 μM with a detection limit of 0.27 μM. Besides, it was successfully applied to the analysis of tap water and Yangtze river water. Our strategy can be used to assess the activity of LACC, and it also provided a novel way to construct other enzyme-based biosensors.Graphical abstractGraphical abstract for this article
       
  • Disposable piezoelectric vibration sensors with PDMS/ZnO transducers on
           printed graphene-cellulose electrodes
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): Dogan Sinar, George K. KnopfThe individual components and circuitry of single-use flexible electronic sensors must be designed and fabricated to maintain stable functionality during normal operation, but once the usefulness of the device has concluded it is often incinerated or disposed of in a landfill. It is critical, therefore, that environmentally benign materials and fabrication processes be used to create these sensors such that manufacturing and disposal processes do not result in toxic or hazardous by-products. This paper introduces a novel flexible piezoelectric vibration sensor based on interdigitated electrodes (IDEs) printed on polymer-coated paper substrates using nontoxic graphene nanoparticle (G) and carboxymethyl cellulose (G-CMC) aqueous suspensions as the electrically conductive ink. The piezoelectric transducer consists of environmentally benign zinc oxide (ZnO) nanoparticles dispersed in a polydimethylsiloxane (PDMS) matrix. During fabrication, the PDMS/ZnO composite is spin coated on the inkjet printed G-CMC interdigitated electrodes forming a thin piezoelectric layer. The fabricated sensors are tested, without additional signal amplification, for direct force response and low amplitude vibrations. A repetitive 6.3 N impact force, at very low frequencies (1–2.37 Hz), generated up 541 mVp-p. A further study of low-amplitude vibrations, over the frequency range of 50 Hz to 2.5 kHz, produced voltage outputs from 25 mVp-p to 452 mVp-p. Single-use force and vibration sensors over these low frequency ranges can be used for intelligent packaging, temporary monitoring of the environment and disposable wearable technologies.Graphical abstractGraphical abstract for this article
       
  • Analysis and test of a novel pre-compressed cruciform energy harvester
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): Mingli Li, Renjing Gao, Shutian Liu, Liyong TongThis paper presents a novel pre-compressed cruciform energy harvester (PCEH) with low resonant frequency, wide usable bandwidth, and large voltage peak. The doubly-symmetrical PCEH consists of a pre-compressed main beam with piezoelectric patches and two side beams with concentrated masses attached to free ends. The geometry of the introduced side beams and the pre-compressive force can effectively adjust the overall equivalent mass and stiffness of the proposed PCEH, which in turn affect key properties such as resonant frequency, voltage peak and usable bandwidth. Based on the Euler–Bernoulli beam theory and the electromechanically coupled theory, a mechanical model of the novel PCEH is proposed and developed to capture the effects of the side beam geometry and the pre-compressive force on key properties, and subsequently validated by finite element analysis (FEA) and experiments. A comparison between the PCEH and the commonly used pre-compressed energy harvester (PEH) with equal total mass reveals that the newly introduced side beams improve the performances of the PCEH. For example, when a 135N pre-compressive force is applied to both PEH and PCEH, the resonant frequency of the present PCEH is 43.52 % lower than that of the reference PEH by tuning the length of the side beam, and the voltage peak and usable bandwidth of the present PCEH are 149.35 % higher and 35.84 % wider than those of the reference PEH, respectively. A good agreement among the theoretical, FEA and experimental results of the present PCEH is fully verified.Graphical abstractGraphical abstract for this article
       
  • Structure dependence of the output performances of a self-deformation
           driving (SDD) piezoelectric actuator
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): Zhixin Yang, Xiaoqin Zhou, Hu HuangPre-loading the driving compliant mechanism is an effective method to improve the self-locking ability of the parasitic motion principle (PMP) piezoelectric actuators, but it may also change the motion mode from the normal PMP to the self-deformation driving (SDD). When the self-deformation is distributed along the whole driving compliant mechanism, the structure design and analysis would be difficult. To facilitate the design and analysis of SDD piezoelectric actuators, following our previous study, an additional flexible hinge was introduced to the lever-amplification compliant mechanism, and thus the self-deformation would be concentrated in the introduced flexible hinge. The maximum one-step displacement of the proposed SDD piezoelectric actuator was analyzed by pseudo-rigid-body method, and the effects of the radius of the introduced right-circular flexible hinge on its compliance were theoretically analyzed. Output performances of the SDD actuator under various radiuses were characterized by experiments. The results showed that the introduced flexible hinge could not only increase the peak motion speed but also increase the adjustable initial gap, i.e. reducing the assembly requirements. Furthermore, when reducing the initial gap to be over the one corresponding to the peak motion speed, the backward motion would become remarkable; however, it would also bring an important advantage, improving the self-locking ability (also the loading capability). These results are expected to provide useful information for the design and application of SDD piezoelectric actuators.Graphical abstractGraphical abstract for this article
       
  • Fluorescent carbon nanodots as efficient nitro aromatic sensor- analysis
           based on computational perspectives
    • Abstract: Publication date: 1 February 2020Source: Sensors and Actuators A: Physical, Volume 302Author(s): V.A Ansi, K.R. Vijisha, K. Muraleedharan, N.K. RenukaHerein, cyan emitting carbon dots are synthesised by adopting a facile, green and economic route using table sugar as the precursor. The system is adequately characterized by TEM, XRD, XPS, FTIR, Raman spectroscopy, Zeta potential analysis, UV–vis absorbance spectroscopy and Fluorescence spectroscopy. Excitation dependent emission is exhibited by these particles.The luminescence exhibited by these dots is found to be highly sensitive towards a collection of aromatic nitro compounds which enabled their sensing with admirable efficacy. Limits of detection towards the nitro aromatic systems are found to be in the range of 270–1720 Femto molar (fM), which is highly commendable while considering the benchmark values prescribed for the nitro aromaticsin aqueous systems, by the concerned authorities. The proposed carbon dot unit performed well even under complex chemical environments, as illustrated by the negligible interference of common metal salts and bio-moleculesin the sensing action. Besides, the observed sensing trend isscientifically corroborated with the aid ofwidely accepted computational analytical tools, Global reactive descriptors and Donor Acceptor Map (DAM) methods. Interpretation of sensing phenomena in a computational perspective is a novel attempt in the area of fluorimetric sensing, since works in the concerned area seldom seeks the assistance of a scientific MAP or parameter for explaining the sensing action.Graphical abstractGraphical abstract for this article
       
  • Aluminum doped zinc oxide (AZO)-based pressure sensor
    • Abstract: Publication date: Available online 2 January 2020Source: Sensors and Actuators A: PhysicalAuthor(s): Victor Samoei, Ahalapitiya H. JayatissaThe feasibility of using aluminum-doped zinc oxide (AZO) as a piezoresistive pressure sensor material is reported. AZO has attracted a great deal of attention in many applications because of its nontoxicity, abundancy and lower cost than other materials such as indium tin oxide (ITO). The AZO films were deposited on polyethylene (PE) substrates by a radio-frequency (rf) magnetron sputtering method and they were used as the diaphragms of the pressure sensors. The piezoresistive sensor was tested for different pressures in vacuum and gage pressure conditions. The response characteristics indicated that resistance increased with the bending of the AZO layer in both compressive and tensile operation modes. The sensor characteristics exhibited that the AZO piezoresistive sensor can be used to measure ambient pressure quantitatively. This investigation indicated that AZO can be used as an alternative material for the fabrication of pressure sensors.Graphical abstractGraphical abstract for this article
       
  • Developing High-Sensitivity UV Sensors Based on ZnO Nanorods Growth on
           TiO2 Seed Layer films using Solution Immersion Method
    • Abstract: Publication date: Available online 31 December 2019Source: Sensors and Actuators A: PhysicalAuthor(s): N.A.M. Asib, F.S. Husairi, K.A. Eswar, A.N. Afaah, M.H. Mamat, M. Rusop, Z. KhusaimiTiO2:ZnO nanorods thin film has the great properties of packed ZnO nanorods with good crystallinity and improved UV absorption properties which are suitable for optoelectronic device applications. ZnO nanorods array was fabricated by using a seeding method with TiO2 as seed layer. As a result, well aligned of ZnO rods with good distribution can grow. Different samples of TiO2, ZnO and TiO2:ZnO nanorods thin film were used as based material in UV sensor devices. The responsivities of the sensors are 1.70 × 10-1A/W, 7.76 × 10-5 A/W and 2.22 × 10-7 A/W for TiO2:ZnO nanorods, TiO2 seed layer and ZnO rods based UV sensors respectively. Results indicate that the TiO2:ZnO nanorods UV sensor exhibits rapid and high response to UV light compared with TiO2 and ZnO sensor because of its small size of nanorods and seed layer acting as an absorbance assisted and capacitive layer on the glass surface.Graphical Graphical abstract for this article
       
  • Resonance Frequency Selective Electromagnetic Actuation for
           High-Resolution Vibrotactile Displays
    • Abstract: Publication date: Available online 28 December 2019Source: Sensors and Actuators A: PhysicalAuthor(s): Ali Mohammadi, Mahmoud Abdelkhalek, Shamin SadrafshariVibrotactile displays offer significant potential for conveying information through the sense of touch in a wide variety of applications. Spatial resolution of these displays is limited by the large size of actuators. We present a new selective electromagnetic actuation technique to control the vibrations of multiple tactile elements using a single coil based on their individual mechanical resonance frequencies. This technique allows low-cost and highly reliable implementation of many tactile elements on a smaller area. A prototype is manufactured using 3D-printed tactile elements and off-the-shelf coils to characterize the proposed technique. This prototype successfully increases the resolution by 100% from 16 to 32 tactile pixels (taxels) on a 25 cm2 pad, without sacrificing other performance metrics such as refresh rates and power consumption. The multiphysics finite element analysis developed for this new actuation technique are experimentally validated by optical vibrometry measurements. This work demonstrates the capability of resonance-selective electromagnetic actuator in developing high-resolution low-cost vibrotactile displays.Graphical abstractGraphical abstract for this article
       
  • New modifications of a bennet doubler circuit-based electrostatic
           vibrational energy harvester
    • Abstract: Publication date: Available online 27 December 2019Source: Sensors and Actuators A: PhysicalAuthor(s): V.P. Dragunov, D.I. Ostertak, R.E. SinitskiyIn this work, theoretical and experimental studies of the conditioning circuit based on the Bennet doubler with a power source in a variable capacitor branch having one, two and three variable capacitors are carried out for electrostatic vibrational energy harvesters (e-VEHs). Analytical expressions for evaluation of the e-VEH conditioning circuit main parameters are derived. All three modifications of the conditioning circuit have two operation modes: autostabilization and the mode of unlimited capacitors charge and voltage growth. The change between the operation modes for one-, two- and three-capacitor circuits with switches takes place when the maximal-to-minimal capacitance ratio η is equal to 2, 1.618 and 1.414, respectively. For e-VEHs with switches in the autostabilization regime, a three-capacitor circuit will be the most efficient when the capacitance modulation depth η is less than 1.414, a two-capacitor circuit will be the most efficient when 1.414 < η < 1.618, and, for 1.618 < η < 2, the most efficient will be a one-capacitor circuit. In the steady-state autostabilization mode, the saturation voltage will be greater than the primary voltage source V0 if the capacitance modulation depth η is greater than 1.5, 1.366 and 1.302 for the circuit with one, two and three variable capacitors, respectively. The use of diodes instead of switches in the circuits results in the decrease of saturation voltage and leads to the increase of the critical values of ηcr when the change between the operation modes occurs. As the diode inverse currents increase, the effect of the saturation voltage reduction in the autostabilization mode becomes stronger and can even lead to the circuit nonoperabilities. The employment of the Bennet doubler based conditioning circuit modifications considered here enables solving its two main problems: operation only for the capacitance modulation depth more than 2 and the uncontrolled capacitors charge and voltage growth. It should be noted that the observed two conditioning circuit operation regimes will be also inherent for electret vibrational microgenerators and for microgenerators based on using electrodes with materials having different work functions. In addition, the considered two- and three-capacitor circuits make it possible to use e-VEHs at lower values of an external mechanical force or with greater stiffness of spring suspensions minimizing the pull-in effect probability.Graphical abstractGraphical abstract for this article
       
  • Acoustic Radiation Characteristics of Piezoelectric Shells with Internal
           and External Axial Stepped-Thickness Configurations
    • Abstract: Publication date: Available online 26 December 2019Source: Sensors and Actuators A: PhysicalAuthor(s): Ahmed M. Al-Jumaily, Ata Meshkinzar, Paul D. Harris, Loulin HuangUsing stepped-thickness variations, this work aims at amplifying the strength of the focused acoustic field generated inside a hollow piezoelectric cylindrical tube transducer without increasing the driving power. This requires a full understanding of the vibration and acoustic radiation characteristics of various configurations of piezoelectric tube transducers with internal and external axial stepped-thickness variations. A uniform-thickness cylindrical shell is machined at specific regions to acquire a stepped-thickness cylindrical shell with thin-walled regions. The design procedure includes determining the location and number of these thin regions. ANSYS software is used to determine the frequencies and mode shapes of various configurations of these shells. However, stress concentration, as an important design consideration, is also scrutinized at the step regions to avoid exceeding the material fatigue limit. An optimum design configuration for the stepped-thickness transducer is identified. Stronger acoustic fields are obtained using geometrical variations without any increase in the driving power. The simulations are validated experimentally with reasonable agreement.Graphical abstractGraphical abstract for this article
       
  • Dimension Effects of a Magnetoelectric Gyrator with FeCoSiB/Pb(Zr,Ti)O3
           Layered Composites Core for Efficient Power Conversion
    • Abstract: Publication date: Available online 26 December 2019Source: Sensors and Actuators A: PhysicalAuthor(s): Xin Zhuang, Christophe Dolabdjian, Chung Ming Leung, Juran Xu, Jitao Zhang, Gopalan Srinivasan, Jiefang Li, D. ViehlandA Magneto-Electric (ME) gyrator with a superior power efficiency of 95 % has been achieved based on a two-phase solid-state ME laminate. This ME gyrator consists of a winding coil that generates a magnetic field as the first step to realize electromagnetic energy transfer. A magneto-electric composite, serving as the second step, then converts the power from magnetic to electric forms. The laminate consists of two iron-cobalt based amorphous alloy layers bonded to a lead zirconate titanate plate. It has a giant magneto-electric coefficient of around 2200 (V/cm)/Oe at its mechanical resonant frequency (≈ 44 kHz) in structure. Approaching methods based on maximum power transfer (MPT) efficiency theory and the equivalent loss factor (ELF) from the input port have been introduced to evaluate the power efficiency of the ME gyrator. The expected MPT efficiency is 96.5 % at a power volume density of 0.1 Watt/in3 (6.1 mWatt/cm3), and 93.2 % up to 20 Watt/in3 (1.22 Watt/cm3). The ELF explains that the magnetomechanical conversion efficiency is related to the volume of the magnetic phase which is the dominating term in the power efficiency.Graphical abstractGraphical abstract for this articleCurrent-to-voltage conversion ratio (a) as a function of the magnetic bias, (b) as a function of the load resistor and (c) as a function of the power density. Input and output power levels (d) as a function of the magnetic bias, (e) as a function of the load resistor and (f) as a function of the power density. Power efficiency (g) as a function of the magnetic bias, (h) as a function of the load resistor and (i) as a function of the power density.
       
  • Light-induced capacitance switching in spiropyran-based capacitors
    • Abstract: Publication date: Available online 24 December 2019Source: Sensors and Actuators A: PhysicalAuthor(s): Mariacristina Gagliardi, Francesca Pignatelli, Virgilio MattoliPhotoresponsive components for electric and electronic systems have received considerable attention, mainly due to the low cost of used materials and their manufacturing in mild conditions. Optically responsive materials have been prepared blending polymers with photochromic molecules to obtain systems with tuneable properties. Among photoresponsive systems, some have been developed to provide light-induced capacitance switching. Reported systems have been obtained from polymeric blends with azobenzenes and diarylethenes, while spiropyran copolymers were not yet fully investigated. To form a better view of photochromic materials performances in this field, we report the behaviour of three spiropyran-based dielectric materials in active capacitors. We studied the UV- and temperature-dependent switching of systems by varying test conditions. Materials, selected on their thermomechanical properties, clearly indicate their optical responsiveness, with significant dielectric properties changes in respect to reference materials non containing spiropyran moieties. We also demonstrate that light-induced capacitance switching is mainly related to spiropyran-to-merocyanine isomerization, thus the phenomenon is reversible after the inverse isomerization in the dark. The observed reversible and replicable capacitance switching allows using prepared materials in reusable responsive electronic systems.Graphical abstractGraphical abstract for this article
       
 
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