Pub Date : 2024-10-08DOI: 10.1109/JERM.2024.3465354
William Mathieu;Milica Popović;Reza Farivar
The performance of a conformal occipital receive-only radio-frequency (RF) array is demonstrated at 3T. The ultimate aim of this larger coil is to improve whole-brain magnetic resonance imaging (MRI) regardless of a person's head size and shape. The occipital array contains 18-channels built on a 3D-printed 3-mm thick thermoplastic polyurethane (TPU) plate, which acts as a flexible substrate. To show the performance improvements of our design a comparative study was performed where three differently shaped phantoms were used when imaging by our occipital array then by a standard rigid 64-channel head product coil (posterior 40-channel section only). Signal-to-noise-ratio (SNR) and noise correlation performance were evaluated. Compared to the product coil, the flexible occipital array improved mean SNR by 2.8×. Noise correlation was comparable to the product coil. These results lead us to conclude that our design represents a viable approach to improve SNR for differently shaped heads and supports the feasibility of a larger 128-channel size-adaptable whole-head array currently in development.
{"title":"Size-Adaptive Occipital 18-Channel Receive-Only RF Coil for 3T MRI","authors":"William Mathieu;Milica Popović;Reza Farivar","doi":"10.1109/JERM.2024.3465354","DOIUrl":"https://doi.org/10.1109/JERM.2024.3465354","url":null,"abstract":"The performance of a conformal occipital receive-only radio-frequency (RF) array is demonstrated at 3T. The ultimate aim of this larger coil is to improve whole-brain magnetic resonance imaging (MRI) regardless of a person's head size and shape. The occipital array contains 18-channels built on a 3D-printed 3-mm thick thermoplastic polyurethane (TPU) plate, which acts as a flexible substrate. To show the performance improvements of our design a comparative study was performed where three differently shaped phantoms were used when imaging by our occipital array then by a standard rigid 64-channel head product coil (posterior 40-channel section only). Signal-to-noise-ratio (SNR) and noise correlation performance were evaluated. Compared to the product coil, the flexible occipital array improved mean SNR by 2.8×. Noise correlation was comparable to the product coil. These results lead us to conclude that our design represents a viable approach to improve SNR for differently shaped heads and supports the feasibility of a larger 128-channel size-adaptable whole-head array currently in development.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":"9 2","pages":"166-172"},"PeriodicalIF":3.0,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144117318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-07DOI: 10.1109/JERM.2024.3468715
Lucas Banting;Joe LoVetri;Ian Jeffrey
A microwave imaging method that directly incorporates S-parameters into its objective function is presented. S-parameters are extracted from a time-harmonic finite-element model of an imaging system using an efficient thin-wire antenna sub-grid technique. The microwave imaging system considered is an air-based quasi-resonant imaging chamber that is excited with monopole antennas constructed using actual thin wires. Forward modelling results demonstrate the thin-wire model is accurate over the broad band of frequencies tested. A modified contrast source inversion algorithm that incorporates the measured and modelled S-parameters within its objective function is used to reconstruct the complex-valued permittivity of a simple oil-glycerin-water based breast phantom. Image accuracy metrics demonstrate that single frequency experimental inversion results using the thin-wire antenna model and S-parameter objective function improve tumour detection and artifact reduction for the tested breast phantom.
{"title":"Microwave Imaging on S-Parameters Using FEM Thin-Wire Subcell Models","authors":"Lucas Banting;Joe LoVetri;Ian Jeffrey","doi":"10.1109/JERM.2024.3468715","DOIUrl":"https://doi.org/10.1109/JERM.2024.3468715","url":null,"abstract":"A microwave imaging method that directly incorporates S-parameters into its objective function is presented. S-parameters are extracted from a time-harmonic finite-element model of an imaging system using an efficient thin-wire antenna sub-grid technique. The microwave imaging system considered is an air-based quasi-resonant imaging chamber that is excited with monopole antennas constructed using actual thin wires. Forward modelling results demonstrate the thin-wire model is accurate over the broad band of frequencies tested. A modified contrast source inversion algorithm that incorporates the measured and modelled S-parameters within its objective function is used to reconstruct the complex-valued permittivity of a simple oil-glycerin-water based breast phantom. Image accuracy metrics demonstrate that single frequency experimental inversion results using the thin-wire antenna model and S-parameter objective function improve tumour detection and artifact reduction for the tested breast phantom.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":"9 3","pages":"263-269"},"PeriodicalIF":3.2,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144904669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Metasurfaces enable magnetic resonance imaging (MRI) without cables inside the bore by locally improving the sensitivity of scanner-integrated receive coils. This study systematically evaluates a novel grid design to provide signal enhancement for patient imaging. The potential of the proposed metasurface grid design was analyzed regarding its unit cell density and compared with stripe type metasurfaces. The effects were examined in-depth by numerical simulation, workbench measurements, and MRI experiments at 3 Tesla. Differences in the signal-to-noise ratio (SNR) using either the integrated body or spine coils were evaluated, as well as the influence of the metasurface orientation. The grid design provided a favorable eigenmode usable for MR imaging, where it has shown significantly less dependence on orientation, compared to stripe metasurfaces. With the densest grid, more than 26% higher SNR than its most spaced design was achieved. Combining the metasurface for imaging with the spine coil proved to be superior to the body coil. Applying the metasurface for knee imaging, the SNR was locally enhanced by more than 10-fold compared to the scan with only the spine coil. The high-density grid metasurfaces provided benefits compared to the multitude of designs evaluated. This work provides a comprehensive foundation for future developments of metasurfaces for MRI, whose advantages may be exploited e.g. in the domain of interventional radiology.
{"title":"Impact of Unit Cell Density on Grid and Stripe Metasurfaces for MRI Receive Enhancement","authors":"Robert Kowal;Lucas Knull;Ivan Vogt;Max Joris Hubmann;Daniel Düx;Bennet Hensen;Frank Wacker;Oliver Speck;Holger Maune","doi":"10.1109/JERM.2024.3458078","DOIUrl":"https://doi.org/10.1109/JERM.2024.3458078","url":null,"abstract":"Metasurfaces enable magnetic resonance imaging (MRI) without cables inside the bore by locally improving the sensitivity of scanner-integrated receive coils. This study systematically evaluates a novel grid design to provide signal enhancement for patient imaging. The potential of the proposed metasurface grid design was analyzed regarding its unit cell density and compared with stripe type metasurfaces. The effects were examined in-depth by numerical simulation, workbench measurements, and MRI experiments at 3 Tesla. Differences in the signal-to-noise ratio (SNR) using either the integrated body or spine coils were evaluated, as well as the influence of the metasurface orientation. The grid design provided a favorable eigenmode usable for MR imaging, where it has shown significantly less dependence on orientation, compared to stripe metasurfaces. With the densest grid, more than 26% higher SNR than its most spaced design was achieved. Combining the metasurface for imaging with the spine coil proved to be superior to the body coil. Applying the metasurface for knee imaging, the SNR was locally enhanced by more than 10-fold compared to the scan with only the spine coil. The high-density grid metasurfaces provided benefits compared to the multitude of designs evaluated. This work provides a comprehensive foundation for future developments of metasurfaces for MRI, whose advantages may be exploited e.g. in the domain of interventional radiology.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":"9 2","pages":"198-205"},"PeriodicalIF":3.0,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10685136","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144117319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-20DOI: 10.1109/JERM.2024.3454332
Jingtao Liu;Fei Tong;Changzhan Gu
Non-contact vital sign detection using Continuous-Wave (CW) radar is subject to noises and clutters. The heterodyne architecture of the radar transceiver resolves the flicker noise. However, it still suffers from other noise components. Moreover, the presence of clutter also significantly introduces distortions in the sensing results. In this paper, an extended Noise-Immune Motion Sensing (ENIMS) technique is proposed to tackle the noise and clutters simultaneously in the low intermediate-frequency (IF) CW radar. It works by synthesizing I/Q signals at the IF peak of the spectra of the sequentially divided signal segments. Each segment generates one pair of I/Q data points and thus improves the signal-to-noise ratio (SNR). During this process, clutters are also converted into DC components of the I/Q signals. The circle-fitting-based DC compensation technique can thus be used to resolve the clutter issues. High-accurate displacement motion is then reconstructed with the DC-compensated I/Q signals. The theory and noise performance analysis are presented. Simulation and experiments show that, with the proposed technique, the SNR is improved by around 34 dB. Mechanical vibration as small as 90 μm and the subject person's breath and heartbeat at 3.2 m away from the 5. 8 GHz radar were detected under cluttered office environments with a small transmitting power of only 10 μW, whereas the conventional methods fail in the same cases.
{"title":"Non-Contact Vital Sign Detection With High Noise and Clutter Immunity Based on Coherent Low-IF CW Radar","authors":"Jingtao Liu;Fei Tong;Changzhan Gu","doi":"10.1109/JERM.2024.3454332","DOIUrl":"https://doi.org/10.1109/JERM.2024.3454332","url":null,"abstract":"Non-contact vital sign detection using Continuous-Wave (CW) radar is subject to noises and clutters. The heterodyne architecture of the radar transceiver resolves the flicker noise. However, it still suffers from other noise components. Moreover, the presence of clutter also significantly introduces distortions in the sensing results. In this paper, an extended Noise-Immune Motion Sensing (ENIMS) technique is proposed to tackle the noise and clutters simultaneously in the low intermediate-frequency (IF) CW radar. It works by synthesizing <italic>I/Q</i> signals at the IF peak of the spectra of the sequentially divided signal segments. Each segment generates one pair of <italic>I/Q</i> data points and thus improves the signal-to-noise ratio (<italic>SNR</i>). During this process, clutters are also converted into DC components of the <italic>I/Q</i> signals. The circle-fitting-based DC compensation technique can thus be used to resolve the clutter issues. High-accurate displacement motion is then reconstructed with the DC-compensated <italic>I/Q</i> signals. The theory and noise performance analysis are presented. Simulation and experiments show that, with the proposed technique, the <italic>SNR</i> is improved by around 34 dB. Mechanical vibration as small as 90 <italic>μ</i>m and the subject person's breath and heartbeat at 3.2 m away from the 5. 8 GHz radar were detected under cluttered office environments with a small transmitting power of only 10 <italic>μ</i>W, whereas the conventional methods fail in the same cases.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":"9 1","pages":"90-100"},"PeriodicalIF":3.0,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1109/JERM.2024.3419026
Daisuke Nishihara;Kensuke Sasaki;Rasyidah Hanan Binti Mohd Baharin;Tomoaki Nagaoka;Osamu Hashimoto;Ryosuke Suga
In recent years, the guidelines/standards of human exposures to electromagnetic fields have been revised and a new metric referred to as absorbed/epithelial power density (APD) is specified as the basic restriction in the frequency range from 6 to 300 GHz. In this paper, we focus on the development of low-loss phantoms that can model the electromagnetic interaction between an antenna/device and skin in the quasi-millimeter and millimeter-wave frequencies using electromagnetic simulation. The phantom will be used for APD assessment based on field measurement at 28 GHz. It was found that polyphenylene-ether (PPE), which is typically used for antenna substrates, enables the accurate assessment of APD on the skin surface regardless of the antenna type, and that it is rendered suitable as a phantom for APD assessment by optimizing the thickness of low-loss materials with respect to relative permittivity in the range from 10 to 28.5 at 28 GHz.
{"title":"Development of Measurement Phantom for Absorbed Power Density Assessment by Human Exposure at 28 GHz Band","authors":"Daisuke Nishihara;Kensuke Sasaki;Rasyidah Hanan Binti Mohd Baharin;Tomoaki Nagaoka;Osamu Hashimoto;Ryosuke Suga","doi":"10.1109/JERM.2024.3419026","DOIUrl":"https://doi.org/10.1109/JERM.2024.3419026","url":null,"abstract":"In recent years, the guidelines/standards of human exposures to electromagnetic fields have been revised and a new metric referred to as absorbed/epithelial power density (APD) is specified as the basic restriction in the frequency range from 6 to 300 GHz. In this paper, we focus on the development of low-loss phantoms that can model the electromagnetic interaction between an antenna/device and skin in the quasi-millimeter and millimeter-wave frequencies using electromagnetic simulation. The phantom will be used for APD assessment based on field measurement at 28 GHz. It was found that polyphenylene-ether (PPE), which is typically used for antenna substrates, enables the accurate assessment of APD on the skin surface regardless of the antenna type, and that it is rendered suitable as a phantom for APD assessment by optimizing the thickness of low-loss materials with respect to relative permittivity in the range from 10 to 28.5 at 28 GHz.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":"9 2","pages":"191-197"},"PeriodicalIF":3.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144117169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Microwave-based breast imaging (MBI) is an emerging modality that may serve as a screening tool due to the relatively large dielectric contrast between malignant and healthy tissues, the relatively low cost and small size of microwave hardware, and the favourable safety profile of non-ionizing microwave imaging. After more than two decades of research into MBI and several published clinical trials, challenges remain before the modality can be used clinically. Existing estimates of the diagnostic specificity are relatively low, between 20–65%. As a result of the limited specificity of the technique, existing radar-based image reconstruction algorithms have not demonstrated sufficient accuracy for breast cancer diagnosis. This article proposes using enhanced physics modelling (EPM) to improve the accuracy of the physics models used in image reconstruction to address the limited diagnostic accuracy. The results obtained in this study indicated that using EPM significantly improved the area under the curve (AUC) of the receiver operating characteristic curve. The AUC was improved from (84 $pm$ 1)% to (92 $pm$ 1)% through the use of EPM, demonstrating the potential of physics-informed radar-based image reconstruction in MBI.
{"title":"Enhanced Physics Modelling in Radar-Based Microwave Imaging for Breast Cancer Detection","authors":"Tyson Reimer;Spencer Christie;Illia Prykhodko;Stephen Pistorius","doi":"10.1109/JERM.2024.3453994","DOIUrl":"https://doi.org/10.1109/JERM.2024.3453994","url":null,"abstract":"Microwave-based breast imaging (MBI) is an emerging modality that may serve as a screening tool due to the relatively large dielectric contrast between malignant and healthy tissues, the relatively low cost and small size of microwave hardware, and the favourable safety profile of non-ionizing microwave imaging. After more than two decades of research into MBI and several published clinical trials, challenges remain before the modality can be used clinically. Existing estimates of the diagnostic specificity are relatively low, between 20–65%. As a result of the limited specificity of the technique, existing radar-based image reconstruction algorithms have not demonstrated sufficient accuracy for breast cancer diagnosis. This article proposes using enhanced physics modelling (EPM) to improve the accuracy of the physics models used in image reconstruction to address the limited diagnostic accuracy. The results obtained in this study indicated that using EPM significantly improved the area under the curve (AUC) of the receiver operating characteristic curve. The AUC was improved from (84 <inline-formula><tex-math>$pm$</tex-math></inline-formula> 1)% to (92 <inline-formula><tex-math>$pm$</tex-math></inline-formula> 1)% through the use of EPM, demonstrating the potential of physics-informed radar-based image reconstruction in MBI.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":"9 2","pages":"183-190"},"PeriodicalIF":3.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144117268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-30DOI: 10.1109/JERM.2024.3435075
Hao Zhang;Xiaozhou Zhou;Wenlong Zhou
Pulse generators in implantable medical devices need to be programmable and miniaturized. However, the existing designs of pulse generator cannot satisfy both of the requirements at the same time. This paper presents a novel design of pulse generators applying magnetic resonance, which is composed of a class-C inverter and an envelope detector, for implantable medical devices. Through simulation and tests, we verify the superiority of our design in programmability of the output pulse signal and miniaturization of the implants, compared with the conventional designs. The amplitude, frequency and duty cycle of the output pulse signal of the implanted receiver can be modulated by controlling the input signal of the transmitter outside the human body. And the footprint of the implanted receiver can be miniaturized to 12 mm × 14 mm × 5 mm, which is smaller than half the size of most of the existing products.
植入式医疗设备中的脉冲发生器需要可编程和小型化。然而，现有的脉冲发生器设计不能同时满足这两种要求。本文提出了一种新型的用于植入式医疗器械的磁共振脉冲发生器，该脉冲发生器由c类逆变器和包络检测器组成。通过仿真和测试，验证了该设计在输出脉冲信号的可编程性和植入物的小型化方面的优越性。通过控制人体外发射器的输入信号，可以调制植入接收器输出脉冲信号的幅度、频率和占空比。植入接收器的占地面积可缩小至12 mm × 14 mm × 5 mm，小于大多数现有产品的一半。
{"title":"Programmable Pulse Generator by Envelope Detection for Implantable Medical Devices","authors":"Hao Zhang;Xiaozhou Zhou;Wenlong Zhou","doi":"10.1109/JERM.2024.3435075","DOIUrl":"https://doi.org/10.1109/JERM.2024.3435075","url":null,"abstract":"Pulse generators in implantable medical devices need to be programmable and miniaturized. However, the existing designs of pulse generator cannot satisfy both of the requirements at the same time. This paper presents a novel design of pulse generators applying magnetic resonance, which is composed of a class-C inverter and an envelope detector, for implantable medical devices. Through simulation and tests, we verify the superiority of our design in programmability of the output pulse signal and miniaturization of the implants, compared with the conventional designs. The amplitude, frequency and duty cycle of the output pulse signal of the implanted receiver can be modulated by controlling the input signal of the transmitter outside the human body. And the footprint of the implanted receiver can be miniaturized to 12 mm × 14 mm × 5 mm, which is smaller than half the size of most of the existing products.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":"9 1","pages":"80-89"},"PeriodicalIF":3.0,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-29DOI: 10.1109/JERM.2024.3447469
Pouya Mehrjouseresht;Oluwatosin J. Babarinde;Vladimir Volski;Alexander Ye. Svezhentsev;Dominique M. M.-P. Schreurs
Ensuring the safety of electromagnetic exposure stands as an important concern in wireless power transfer (WPT) systems. This work proposes a distributed Fusion Radar WPT (FRWPT) system designed to maintain safe Electric Field Amplitude (EFA) levels at specific locations detected by the radar, primarily where an individual is present. This approach allows for higher EFA in areas without the person, thus optimizing overall power utilization within the system. Also, the radar's ability to detect a person's velocity allows for projecting the person's upcoming location to ensure safety in advance. We introduce an algorithm including power weighting factors for controlling power to not only mitigate dangerous radiation but also maximize power utilization. One significant challenge is the estimation of EFA considering multipath propagation, a common issue in indoor environments. To overcome this, we explore the indoor EFA distribution and suggest a simulation-based method for EFA estimation, taking into account the amplifying effect of the human body on EFA. Experimental results demonstrate that the system successfully maintains EFA below a predefined threshold across various human locations. Moreover, these experiments highlight the system's capability to maximize power utilization ratio (PUR), achieving a value exceeding 50%.
{"title":"Safeguarding Humans From Indoor Wireless Powering via Radar Detection","authors":"Pouya Mehrjouseresht;Oluwatosin J. Babarinde;Vladimir Volski;Alexander Ye. Svezhentsev;Dominique M. M.-P. Schreurs","doi":"10.1109/JERM.2024.3447469","DOIUrl":"https://doi.org/10.1109/JERM.2024.3447469","url":null,"abstract":"Ensuring the safety of electromagnetic exposure stands as an important concern in wireless power transfer (WPT) systems. This work proposes a distributed Fusion Radar WPT (FRWPT) system designed to maintain safe Electric Field Amplitude (EFA) levels at specific locations detected by the radar, primarily where an individual is present. This approach allows for higher EFA in areas without the person, thus optimizing overall power utilization within the system. Also, the radar's ability to detect a person's velocity allows for projecting the person's upcoming location to ensure safety in advance. We introduce an algorithm including power weighting factors for controlling power to not only mitigate dangerous radiation but also maximize power utilization. One significant challenge is the estimation of EFA considering multipath propagation, a common issue in indoor environments. To overcome this, we explore the indoor EFA distribution and suggest a simulation-based method for EFA estimation, taking into account the amplifying effect of the human body on EFA. Experimental results demonstrate that the system successfully maintains EFA below a predefined threshold across various human locations. Moreover, these experiments highlight the system's capability to maximize power utilization ratio (PUR), achieving a value exceeding 50%.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":"9 1","pages":"62-69"},"PeriodicalIF":3.0,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-29DOI: 10.1109/JERM.2024.3442693
Arno Thielens
Wearables on human limbs commonly require wireless connections with other body-worn devices. These links can be established using radio-frequency electromagnetic fields emitted by parallel-plate capacitors (PPCs) as transducing elements. The propagation of the electric (E-) fields emitted by such PPCs on the surface of human limbs is studied by simulations with a stratified, lossy, dielectric cylinder as a limb model. In contrast to currently existing models, this analysis demonstrates that this propagation depends strongly on propagating modes within the lossy dielectric waveguide and that this is associated with an optimal frequency band of operation for such wireless links, which is tied to cut-off frequencies for propagation along the cylindrical waveguide and the radiation efficiency of the PPC, which is also dependent on the limb size. A channel-loss model in the 0.1–1 GHz frequency range is determined based on the simulations. This model is validated using channel loss measurements using a PPC placed on the limbs of three human subjects.
{"title":"Propagation of Radio-Frequency Electromagnetic Fields Emitted by Surface-Mounted Parallel-Plate Couplers Along Human Limbs","authors":"Arno Thielens","doi":"10.1109/JERM.2024.3442693","DOIUrl":"https://doi.org/10.1109/JERM.2024.3442693","url":null,"abstract":"Wearables on human limbs commonly require wireless connections with other body-worn devices. These links can be established using radio-frequency electromagnetic fields emitted by parallel-plate capacitors (PPCs) as transducing elements. The propagation of the electric (E-) fields emitted by such PPCs on the surface of human limbs is studied by simulations with a stratified, lossy, dielectric cylinder as a limb model. In contrast to currently existing models, this analysis demonstrates that this propagation depends strongly on propagating modes within the lossy dielectric waveguide and that this is associated with an optimal frequency band of operation for such wireless links, which is tied to cut-off frequencies for propagation along the cylindrical waveguide and the radiation efficiency of the PPC, which is also dependent on the limb size. A channel-loss model in the 0.1–1 GHz frequency range is determined based on the simulations. This model is validated using channel loss measurements using a PPC placed on the limbs of three human subjects.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":"9 1","pages":"70-79"},"PeriodicalIF":3.0,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-22DOI: 10.1109/JERM.2024.3443782
Chandler Bauder;Abdel-Kareem Moadi;Vijaysrinivas Rajagopal;Tianhao Wu;Jian Liu;Aly E. Fathy
This study presents mm-MuRe, a novel method to perform multi-subject contactless respiration waveform monitoring by processing raw multiple-input-multiple-output mmWave radar data with an end-to-end deep neural network. The traditional vital signs monitoring signal processing scheme for mmWave radar involves analog or digital beamforming, human subject localization, phase variation extraction, filtering, and rate or biomarker analysis. This traditional method has many downsides, including sensitivity to selected beamforming weights and over-reliance on phase variation. To avoid these drawbacks, mm-MuRe (for MM-wave based MUlti-subject REspiration monitoring) is developed to improve reconstruction accuracy and reliability by taking in unprocessed 60 GHz MIMO FMCW radar data and outputting respiratory waveforms of interest, effectively mimicking an adaptive beamformer and bypassing the need for traditional localization and vital signs extraction techniques. Extensive testing across scenarios differing in range, angle, environment, and subject count demonstrates the network's robust performance, with an average cosine similarity exceeding 0.95. Results are compared to two baseline methods and show more than a 10% average improvement in waveform reconstruction accuracy across single and multi-subject scenarios. Coupled with a rapid inference time of 8.57 ms on a 10 s window of data, mm-MuRe shows promise for potential deployment to efficient and accurate near-real-time contactless respiration monitoring systems.
本研究提出了mm-MuRe，一种通过端到端深度神经网络处理原始多输入多输出毫米波雷达数据来执行多受试者非接触式呼吸波形监测的新方法。传统的毫米波雷达生命体征监测信号处理方案包括模拟或数字波束形成、人体受试者定位、相位变化提取、滤波以及速率或生物标志物分析。这种传统的方法有很多缺点，包括对所选波束形成权重的敏感性和对相位变化的过度依赖。为了避免这些缺点，mm-MuRe（基于毫米波的多主体呼吸监测）被开发出来，通过采用未处理的60 GHz MIMO FMCW雷达数据和输出感兴趣的呼吸波形，有效地模仿自适应波束形成器，绕过传统定位和生命体征提取技术的需要，提高重建精度和可靠性。在不同的范围、角度、环境和主题数量的场景中进行的广泛测试表明，该网络具有强大的性能，平均余弦相似度超过0.95。结果与两种基线方法进行了比较，结果显示，在单主题和多主题场景下，波形重建精度平均提高了10%以上。再加上在10秒的数据窗口上8.57毫秒的快速推断时间，mm-MuRe有望部署到高效、准确的近实时非接触式呼吸监测系统中。
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