 Subjects -> ELECTRONICS (Total: 207 journals)
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- IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and
Biology Publication Information-
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PubDate:
March 2023
Issue No: Vol. 7, No. 1 (2023)
- IEEE Journal of Electromagnetics, RF, and Microwaves in Medicine and
Biology About this Journal-
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PubDate:
March 2023
Issue No: Vol. 7, No. 1 (2023)
- Heart ID: Biometric Identification Using Wearable MIMO RF Heart Sensors
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Authors:
Thomas B. Conroy;Xiaonan Hui;Pragya Sharma;Edwin C. Kan;
Pages: 3 - 14
Abstract: Biometric identification (ID) has become increasingly prevalent in the digital era. Static biometric methods, such as fingerprint and facial recognition are widely accepted, yet generally vulnerable to targeted presentation attacks. Current development has expanded to dynamic biometrics, such as gait and electrocardiogram, that enable continuous authentication and are significantly more resistant to presentation attacks. However, dynamic biometrics often involve cumbersome acquisition which restricts their widespread use. Here, we introduce Heart ID, a novel dynamic biometric system that uses near-field coherent sensing (NCS) with a multiple-in multiple-out (MIMO) radio-frequency (RF) antenna setup to non-invasively acquire detailed recordings of internal cardiac dielectric boundary motion over clothing. NCS couples localized energy to the heart to derive interpersonal structural differences, while MIMO significantly increases the biometric entropy compared to single-point observation. We performed a human study of 20 subjects as well as 2 longitudinal evaluations, and employed an unsupervised feature extraction method to explore the ID performance of this new biometric. We found an ensemble classification approach using features derived from unsupervised learning can achieve accuracy exceeding 99% at a 40-second epoch.
PubDate:
March 2023
Issue No: Vol. 7, No. 1 (2023)
- Wireless and Zero-Power Trans-Cardiac Link With Antennified Aortic Valve
Bioprostheses-
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Authors:
Federica Naccarata;Cecilia Occhiuzzi;Roberto Verzicco;Gaetano Marrocco;
Pages: 15 - 23
Abstract: Valvular heart diseases are one of the most common complications in the cardiovascular system. To restore the correct cardiac activity, the failing native heart valve is surgically replaced with a prosthesis. Unfortunately, it often undergoes physio-pathological processes after implantation, including the risks of functional and structural deterioration. Periodic monitoring is hence mandatory all along the life of the patient. As standard screenings are intrusive, this paper proposes a method to exploit the peculiar form-factor of the internal metallic stent of a bioprosthesis as a natural energy harvester to achieve a reliable wireless trans-cardiac RFID-based, battery-free, communication link with no relevant change to the valve. Simulations and tests with a mock-up demonstrate that a robust link with a small size on-skin patch antenna is feasible notwithstanding potential user-specific placement as well as misalignment between the antennas.
PubDate:
March 2023
Issue No: Vol. 7, No. 1 (2023)
- Wirelessly Powered 3-D Printed Headstage Based Neural Stimulation System
for Optogenetic Neuromodulation Application-
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Authors:
Dipon K. Biswas;Nabanita Saha;Ifana Mahbub;
Pages: 24 - 31
Abstract: This work presents a miniaturized wireless power transfer (WPT) system integrated with a neuromodulation headstage for duty-cycled optical stimulation of freely moving rodents. The proposed WPT system is built using the commercially available off-the-shelf components (COTS) for the optogenetic neuromodulation system consisting of a bridge rectifier, a DC-DC converter, an oscillator circuit, an LED driver, and a μLED. The total power consumption of the stimulation system is 14 mW which is provided using the WPT method. The WPT system includes a novel transmitter (TX) coil implemented on a printed circuit board (PCB), and a solenoid receiver (RX) coil wrapped around a customized 3-D printed headstage. The proposed TX coil is designed in such a way that the magnetic field all across the TX coil is sufficient to provide the required power to the optical stimulation system that is worn as a headstage by the freely moving rat. The headstage device's dimension is 18.75 mm × 21.95 mm, weighing 4.75 g. The ratio of the weight of the headstage and rat is 4.75:300. The proposed system is able to achieve a maximum overall efficiency of ∼63% at 5 cm separation between the TX and RX coils, where the maximum power transfer efficiency (PTE) of the WPT system is ∼88% and the power conversion efficiency (PCE) of the rectifier is 71.6%. The proposed system with reconfigurable stimulation frequency is suitable for exciting different brain areas for long-term health monitoring.
PubDate:
March 2023
Issue No: Vol. 7, No. 1 (2023)
- Implementation of Thinned Array Synthesis in Hyperthermia Treatment
Planning of 434 MHz Phased Array Breast Applicator Using Genetic Algorithm
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Authors:
Divya Baskaran;Kavitha Arunachalam;
Pages: 32 - 38
Abstract: Genetic algorithm-based array thinning technique is investigated in this paper to study the performance of our 18-element 434 MHz phased array breast applicator when driven by reduced number of active antennas. Selective power deposition ability was assessed for 18, 15, 12, and 9 active antennas on 25 patient models with varying characteristics. The average hotspot to target quotient of 18-, 15-, 12-, and 9-antenna excitation in 25 patient models was 1.18, 1.09, 1.09, and 1.13, respectively. The average temperature in 50% tumor volume for 18-, 15-, 12-, and 9-antenna excitation was 42.42 °C, 42.48 °C, 42.49 °C, and 42.48 °C, respectively. The temperature induced in tumor and healthy tissues is similar for varying number of active channels. However, the amount of power consumed was 25.2%, 53.9%, 97.9% higher for 15, 12, 9 active antennas compared to the filled array. Antenna array with 12 active elements was chosen as the optimal combination as it provided selective tumor heating with good tradeoff between number of channels and power consumption. The heating ability of the thinned array was assessed for 50% reduction in the number of active antennas on patient derived heterogeneous breast phantoms for five tumor target locations. The good agreement between simulated and measured thermal distributions demonstrate the selective heating ability of our phased array applicator for 50% reduction in hardware resources. The study outcome enables us to realize a cost-effective hyperthermia treatment delivery system.
PubDate:
March 2023
Issue No: Vol. 7, No. 1 (2023)
- Area-Averaged Transmitted and Absorbed Power Density on a Realistic Ear
Model-
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Authors:
Ante Lojić Kapetanović;Giulia Sacco;Dragan Poljak;Maxim Zhadobov;
Pages: 39 - 45
Abstract: At millimeter waves (MMW), the current state of research in computational dosimetry is mainly relying on flat-surface tissue-equivalent models to simplify the exposure assessment by disregarding geometrical irregularities characteristic of conformal surfaces on realistic models. However, this can lead to errors in estimation of dosimetric quantities on non-planar body parts with local curvature radii comparable to the wavelength of the incident field. In this study, we address this problem by developing an averaging technique for the assessment of the absorbed power density ($S_{text{ab}}$) on the anatomically-accurate electromagnetic (EM) model of the human ear. The dosimetric analysis is performed for the plane-wave exposure at 26 and 60 GHz, and the accuracy of the proposed method is verified by using two commercial EM software. Furthermore, we compare the two definitions of $S_{text{ab}}$ provided in the international guidelines and standards for limiting exposure to EM fields above 6 GHz. Results show marginal relative differences between the obtained values from the two different definitions (within about 6 %) in all considered scenarios. On the other hand, in comparison to flat models, the spatial maximum $S_{text{ab}}$ on the ear is up to about 20 % larger regardless of definition. These findings demonstrate a promising potential of the proposed method for the assessment of $S_{text{ab}}$ on surfaces of anatomical models at frequencies upcoming for the 5th generation (5G) wireless networks and beyond
PubDate:
March 2023
Issue No: Vol. 7, No. 1 (2023)
- Attachable DC Coil Array for Improved Functional MRI at 7T
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Authors:
Shuxian Qu;Yang Gao;Jie Zhao;Yi Sun;Xiaotong Zhang;
Pages: 46 - 51
Abstract: The prefrontal cortex (PFC) has long been concerned as an important part in cognitive control of neuroscience field. Functional magnetic resonance imaging (fMRI) has been introduced as an effective neuroimaging technique to explore neural activity. However, images within PFC region are subject to susceptibility artifacts, which give rise to undesired image distortion and signal drop-out. In this work, we proposed a method of adding a static magnetic field with high-order spatial pattern for artifact correction. Based on that, a compact attachable 8-channel coil array was constructed. Two toroid chokes were optimized and connected to each coil loop to minimize radiofrequency coupling. To evaluate the array performance, bench measurements and MRI experiments over phantoms and a human subject at 7T were conducted. With the proposed array applied, only 0.3 MHz and 1 MHz frequency shift were introduced to the RF coil, and no apparent RF performance change was observed; the inhomogeneity was reduced by 15%∼24%; in fMRI images over the human subject, “notorious” artifacts within target region were relatively mitigated. The present setup offers a feasible means for practical artifact correction, which is promising for the research that focuses on PFC regions.
PubDate:
March 2023
Issue No: Vol. 7, No. 1 (2023)
- Asymmetric Tapered Solenoid Designs for Halbach-Based Portable Magnetic
Resonance Imaging-
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Authors:
Meena Rajendran;Shao Ying Huang;
Pages: 52 - 58
Abstract: Halbach array is a popular permanent magnet array used in head dedicated portable MRI. It supplies transversal main magnetic field ($B_{0}$), and it works well with solenoid RF coils when $B_{0}$ is homogeneous. The $B_{0}$ a Halbach array supplies is low. To compensate this, it is desired to have a high coil sensitivity of the solenoid coil that works in such a system. Hence in this paper, an asymmetrical tapered solenoid was proposed and an optimization was carried out for both the coil profile and pitches between turns for high coil sensitivity and homogeneity. Multi-objective genetic algorithm was used. B$_{1}$-field was calculated using Biot-Savart's law in the optimization process. The targeted field of view (FoV) is a 190 mm diameter of spherical volume (DSV) for head imaging. The optimized solenoid coils were simulated using frequency domain solver in CST Microwave studio, physically constructed, and compared with a reference coil of comparable dimensions. The optimal design shows B$_{1}$ field increase of $sim$35% (calculation), $sim$33% (simulation) and minimal trade-off in homogeneity of $sim$10% (calculation and simulation) within 190 mm DSV. For validation, the B$_{1}$ sensitivity of the constructed coils were measured in the FoV on the $xy-$ plane at $z=0$. The measured results are in good agreement with the simulated and calculated results.
PubDate:
March 2023
Issue No: Vol. 7, No. 1 (2023)
- An Image Post-Processing Approach Based on Fully Dense U-Net for Microwave
Induced Thermo-Acoustic Tomography-
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Authors:
Jian Song;Tao Shen;Qingwang Wang;
Pages: 59 - 64
Abstract: In microwave induced thermo-acoustic tomography (TAT), circular scanning sensor array is the general signal acquiring mode. For higher sensitivity, large aperture detectors are widely preferred in the real TAT imaging system. However, large aperture of detector usually results in the limited spatial sampling points. Meanwhile, for considering the safety and comfort, the microwave radiation power is also limited. Due to these limitations, the signal to noise ratio (SNR) of TA signals may not be ideal to reconstruct an image with satisfactory quality. In addition, the TA image often suffers the artifacts resulted by sparsely sampling data. Herein, we propose a deep learning-based scheme to process the TA images which are reconstructed with time reversal (TR) method. Since the obvious artifacts removing performance in photoacoustic tomography (PAT), fully dense U-Net (FD U-Net) is employed to be the base deep learning architecture. Due to the amount limitation of real experimental TA data, the network is mainly trained by synthetic data which are generated in TAT simulating scheme. Furthermore, in order to ensuring the trained network could correctly detect the targets in the TA image, we propose a scheme termed data augmentation FD U-Net (DAFD U-Net) in which a few experimental TA images are added to the training procedure and perform data augmentation.The performance of DAFD U-Net is verified by an experimental image. Results show that the proposed scheme could significantly improve the quality of TAT image.
PubDate:
March 2023
Issue No: Vol. 7, No. 1 (2023)
- Whole-Body Exposure System Using Horn Antennas With Dielectric Lens at 28
GHz-
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Authors:
Sachiko Kodera;Norika Miura;Yinliang Diao;Miyako Inoue;Takashi Hikage;Kenji Taguchi;Hiroshi Masuda;Akimasa Hirata;
Pages: 65 - 72
Abstract: In the revised international guidelines and standard for human protection from electromagnetic fields, the permissible specific absorption rate (SAR) for whole-body exposure has been extended from 3 or 10 GHz to 300 GHz. The rationale for this revision is the extrapolation from findings of conventional radio-frequency exposure and infrared radiation. However, experiments of whole-body exposure in human subjects are limited to a few studies, which were conducted below 6 GHz. In this study, an exposure system at 28 GHz targeting a wide area of the human back was developed, which consists of two horn antennas with a dielectric lens. The effectiveness of the proposed exposure system was evaluated by computational dosimetry and experiments. The computed power absorption and measured distributions in the wave absorber and the back of the human subject were in good agreement. Under the compliance with the local exposure limits, the whole-body average SAR was 0.35 W/kg, which is comparable to the limit for whole-body exposure of 0.4 W/kg for occupational exposure in the international guidelines and standard. The developed exposure system would be useful to evaluate the thermophysiological response to whole-body exposure above 6 GHz.
PubDate:
March 2023
Issue No: Vol. 7, No. 1 (2023)
- Detection of Sodium Ion Imbalance in Human Body Fluids Using an Improved
RF Sensor-
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Authors:
Apala Banerjee;Prakrati Azad;M Jaleel Akhtar;
Pages: 73 - 81
Abstract: A novel radio frequency (RF) sensor is designed, developed, and tested to determine sodium ion imbalance in human body fluids. The proposed sensor consists of a complementary split ring resonators (CSRR)-based structure with the sensing region surrounded by air vias to improve the confinement of the E-field within the sensing region. The proposed RF sensor is designed using the full wave EM simulator, the computer simulation technology (CST) Microwave Studio, and fabricated on Rogers 6002 (${{rm{varepsilon }}}_{mathrm{r}}$ = 2.2) having a thickness of 3.75 mm. The various parameters of the designed sensor are optimized for improved performance, and its equivalent circuit model is developed using the ADS software. The proposed sensor confines the field in the sensing area and the test fluid is injected into the sensing region through a specially designed 1.5 mm fluidic channel made across the width of the substrate. This kind of channel embedded in the substrate limits the quantity of fluid interacting with the sensing region thereby facilitating testing of Simulated Body Fluid (SBF) possessing even high-value permittivity in the range of 80–100. The SBF in the present situation is primarily being used to mimic human blood plasma to detect Na+ concentrations in a lab environment. The developed RF sensor prototype is successfully utilized to determine the Sodium ion constituent variation in the body fluid, which is an important aspect as Na+ concentration affects the metabolic functioning in the body. The measured sensitivity for Na+ ions in the body fluid is recorded to be 0.03 dB/(mmol/dm3) for the fabricated RF sensor.
PubDate:
March 2023
Issue No: Vol. 7, No. 1 (2023)
- An Investigation on Conductive Intracardiac Communication Dynamic Channel
Gain During the Cardiac Cycle for Leadless Pacemakers-
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Authors:
Liting Chen;Yiming Liu;Zhizhang Chen;Sio Hang Pun;Mang I. Vai;Yueming Gao;
Pages: 82 - 89
Abstract: In galvanic coupling conductive intracardiac communication(GCCIC) of the leadless pacemakers, the electrical signal transmitted directly through the myocardium and blood is inevitably affected by the cardiac cycle. Established studies focused more on the effect of the myocardium. However, our preliminary in-vitro experiments suggested that blood volume variations also significantly impacted signal transmission. In this article, we analyzed the blood volume variations during the cardiac cycle and designed an in-vitro experimental platform containing a simulated heart beating system and an automatic channel characteristic acquisition system, which controlled two peristaltic pumps to realize the periodic blood volume variations and the continuous acquisition of channel gain. Through the in-vitro porcine heart experiment, the effect of frequency and blood volume variations during the cardiac cycle on two channel gains was analyzed. Considering the impact of high-frequency signal leakage, the channel gain variations of the low frequency are the main concern. The results showed that the channel gain was positively correlated with frequency; it changed periodically with blood volume variations in the cardiac cycle, and the trends were different due to the different signal paths of the two channels. For the Right Ventricle-Right Atrium channel, the gain varied from $-67$ dB to $-53$ dB and is inversely correlated with blood volume. The gain fluctuation range was smaller for the Right Ventricle-Left Ventricle channel, about 2 dB. This study shows that the gain of intracardiac communication channels, especially the RV-RA channel, is influenced by blood volume variations during the cardiac cycle.
PubDate:
March 2023
Issue No: Vol. 7, No. 1 (2023)
- A Study of Handgrip Force Prediction Scheme Based on Electrical Impedance
Myography-
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Authors:
Pan Xu;Xudong Yang;Wei Ma;Wanting He;Željka Lučev Vasić;Mario Cifrek;Yueming Gao;
Pages: 90 - 98
Abstract: Handgrip force prediction is widely used in the rehabilitation of the arm and prosthetic control. To investigate the effects of different measurement positions and feature parameters on the results of handgrip force prediction, a model based on electrical impedance myography (EIM) and long short-term memory (LSTM) networks was proposed to compare and determine a better scheme for handgrip force prediction. We conducted the signal acquisition experiments of impedance and handgrip force on the anterior forearm muscles and brachioradialis muscle. Afterwards, three evaluation metrics were introduced to compare the prediction results of various models, and the variability between models was analyzed using paired sample t-tests. The results showed that the model of handgrip force prediction based on anterior forearm muscles exhibited better performance in predicting. The evaluation metrics of $mathbf {R^{2}}$, explained variance score (EVS) and normalized mean square error (NMSE) for the model fusing the feature parameters resistance (R) and reactance (X) were 0.9023, 0.9173 and 0.0114, respectively. Therefore, the feature parameters fusing R and X are the optimal input for the handgrip force prediction model. The anterior forearm muscles are the preferred position for impedance measurement over the brachioradialis muscle. This paper validated the feasibility of EIM for handgrip force prediction and provided a new reference and implementation scheme for muscle rehabilitation training and prosthetic control.
PubDate:
March 2023
Issue No: Vol. 7, No. 1 (2023)
- 2022 List of Reviewers
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Pages: 99 - 100
PubDate:
March 2023
Issue No: Vol. 7, No. 1 (2023)
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Hybrid journal (It can contain Open Access articles)
