Pub Date : 2025-11-21DOI: 10.1109/JERM.2025.3632488
{"title":"IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology Publication Information","authors":"","doi":"10.1109/JERM.2025.3632488","DOIUrl":"https://doi.org/10.1109/JERM.2025.3632488","url":null,"abstract":"","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":"9 4","pages":"C2-C2"},"PeriodicalIF":3.2,"publicationDate":"2025-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11263961","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145560659","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}
The dielectric characterization of biological tissues is essential for different medical applications. Due to ethical constraints, comprehensive characterization of human tissues remains a significant challenge. There is a large database of measurements on animals, but limited research has been conducted in humans, especially at the abdominal area at in vivo conditions. This study presents an in-depth analysis of the dielectric properties of human abdominal tissues such as liver, small intestine, and fat, both in vivo and ex vivo. Measurements were conducted both in vivo and ex vivo, using the open-ended coaxial probe method within 0.5 - 26.5 GHz band. Both fat and small intestine tissues were measured at ex vivo and in vivo conditions, while liver was measured only under in vivo conditions. The obtained dielectric properties were analyzed for each tissue and scenario. Results are compared to other reported studies and 2-pole Cole-Cole model parameters are reported to allow reproducibility of the tissue behavior. These findings contribute to expanding the existing database on dielectric properties of human tissues, particularly for abdominal tissues in humans in vivo, of which there are few measurements in the literature.
{"title":"In Vivo and Ex Vivo Dielectric Characterization of Human Tissues in the Abdominal Area at the Microwave Band","authors":"Sergio Micó-Rosa;Matteo Frasson;Narcis Cardona;Vicente Pons-Beltrán;Concepcion Garcia-Pardo","doi":"10.1109/JERM.2025.3625656","DOIUrl":"https://doi.org/10.1109/JERM.2025.3625656","url":null,"abstract":"The dielectric characterization of biological tissues is essential for different medical applications. Due to ethical constraints, comprehensive characterization of human tissues remains a significant challenge. There is a large database of measurements on animals, but limited research has been conducted in humans, especially at the abdominal area at in vivo conditions. This study presents an in-depth analysis of the dielectric properties of human abdominal tissues such as liver, small intestine, and fat, both in vivo and ex vivo. Measurements were conducted both in vivo and ex vivo, using the open-ended coaxial probe method within 0.5 - 26.5 GHz band. Both fat and small intestine tissues were measured at ex vivo and in vivo conditions, while liver was measured only under in vivo conditions. The obtained dielectric properties were analyzed for each tissue and scenario. Results are compared to other reported studies and 2-pole Cole-Cole model parameters are reported to allow reproducibility of the tissue behavior. These findings contribute to expanding the existing database on dielectric properties of human tissues, particularly for abdominal tissues in humans in vivo, of which there are few measurements in the literature.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":"10 1","pages":"107-115"},"PeriodicalIF":3.2,"publicationDate":"2025-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11251205","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146223781","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 : 2025-11-17DOI: 10.1109/JERM.2025.3627493
Shengli Fan;Lin Huang;Yulong Guo;Yijie Huang
Integrated thermoacoustic (TA)/photoacoustic (PA) dual-modal imaging offers complementary contrast by simultaneously mapping dielectric properties and optical absorption of biological tissues, holding considerable clinical promise. To facilitate clinical adoption, there is a pressing need for compact, user-friendly handheld probes. In this work, we present a novel handheld integrated dual-modal probe designed around a custom H-plane bent rectangular horn antenna. A key innovation lies in the system-level integration of a miniaturized microwave source (37 cm × 32 cm × 10 cm) and a compact laser module (60 mm × 34 mm × 26 mm), resulting in a fully portable imaging platform. This system uniquely combines TA imaging for mapping tissue dielectric properties with PA imaging for delineating vascular morphology. The core antenna (34 mm × 17 mm × 90 mm, 84 g), specifically engineered for this probe, operates in the 5.8–6.0 GHz band. Experimental characterization demonstrated a spatial resolution of 1.31 mm for TA imaging and 0.75 mm for PA imaging. The dual-modal capability was successfully validated using tissue-mimicking phantoms containing fine black sutures (0.1 mm diameter) and saline-filled targets (1 mm diameter). Finally, clinical potential was confirmed through in vivo imaging of a human finger. These results collectively affirm that the developed handheld TA/PA probe, based on a compact and novel H-plane bent horn antenna design, represents a significant step forward for clinical applications such as vascular diagnostics, finger joint assessment, and Image-Based Hyperthermia Guidance.
集成热声(TA)/光声（PA）双模成像通过同时映射生物组织的介电特性和光吸收提供互补对比，具有相当大的临床前景。为了促进临床应用，迫切需要紧凑、用户友好的手持探针。在这项工作中，我们提出了一种新型的手持式集成双峰探头，设计围绕定制的h面弯曲矩形喇叭天线。一个关键的创新在于系统级集成了小型化微波源（37厘米× 32厘米× 10厘米）和紧凑型激光模块（60毫米× 34毫米× 26毫米），从而形成了一个完全便携式的成像平台。该系统独特地结合了TA成像来绘制组织介电性质和PA成像来描绘血管形态。核心天线（34 mm × 17 mm × 90 mm, 84 g）是专门为该探头设计的，工作在5.8-6.0 GHz频段。实验表征表明，TA成像的空间分辨率为1.31 mm， PA成像的空间分辨率为0.75 mm。通过组织模拟模型（包含细黑色缝线（直径0.1 mm）和盐水填充靶标（直径1 mm））成功验证了双模态能力。最后，通过人体手指的体内成像证实了临床潜力。这些结果共同证实，开发的手持式TA/PA探针基于紧凑和新颖的h面弯曲角天线设计，在血管诊断、手指关节评估和基于图像的热疗指导等临床应用方面迈出了重要一步。
{"title":"H-plane Bent Horn Antenna-Integrated Handheld Probe for Compact Dual-Modality Thermoacoustic/ Photoacoustic Imaging","authors":"Shengli Fan;Lin Huang;Yulong Guo;Yijie Huang","doi":"10.1109/JERM.2025.3627493","DOIUrl":"https://doi.org/10.1109/JERM.2025.3627493","url":null,"abstract":"Integrated thermoacoustic (TA)/photoacoustic (PA) dual-modal imaging offers complementary contrast by simultaneously mapping dielectric properties and optical absorption of biological tissues, holding considerable clinical promise. To facilitate clinical adoption, there is a pressing need for compact, user-friendly handheld probes. In this work, we present a novel handheld integrated dual-modal probe designed around a custom H-plane bent rectangular horn antenna. A key innovation lies in the system-level integration of a miniaturized microwave source (37 cm × 32 cm × 10 cm) and a compact laser module (60 mm × 34 mm × 26 mm), resulting in a fully portable imaging platform. This system uniquely combines TA imaging for mapping tissue dielectric properties with PA imaging for delineating vascular morphology. The core antenna (34 mm × 17 mm × 90 mm, 84 g), specifically engineered for this probe, operates in the 5.8–6.0 GHz band. Experimental characterization demonstrated a spatial resolution of 1.31 mm for TA imaging and 0.75 mm for PA imaging. The dual-modal capability was successfully validated using tissue-mimicking phantoms containing fine black sutures (0.1 mm diameter) and saline-filled targets (1 mm diameter). Finally, clinical potential was confirmed through in vivo imaging of a human finger. These results collectively affirm that the developed handheld TA/PA probe, based on a compact and novel H-plane bent horn antenna design, represents a significant step forward for clinical applications such as vascular diagnostics, finger joint assessment, and Image-Based Hyperthermia Guidance.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":"10 1","pages":"99-106"},"PeriodicalIF":3.2,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146223743","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}
This article presents an approach for real-time, non-invasive monitoring of hydrogel swelling dynamics using a microwave probe sensor. A compact stripline probe has been designed to detect dielectric variations caused by water uptake in the pharmaceutical hydrogel APO-Metformin XR 1000. Swelling induces changes in effective permittivity, resulting in a measurable downward shift in the resonance frequency, observed through the input reflection coefficient ($S_{11}$). These frequency shifts can then be processed and used to detect the swelling ratio. The operation principle of the probe, its sensitivity, and the design procedure are explained using an accurate circuit model analysis. A prototype of the probe has been fabricated, and experimental measurements using a pharmaceutical hydrogel were conducted to verify the proposed sensing principle. Controlled experiments under consistent mechanical pressure and hydration conditions demonstrated a correlation between hydrogel swelling ratio and resonance frequency shift, with an exponential decay fit (R$^{2}$ = 0.994). Repeatability tests confirmed high measurement stability, with average sensitivity of 90 MHz/g of water absorption. The results highlight the potential of microwave sensing as a sensitive, label-free, and scalable platform for characterizing hydrogel hydration, enabling new opportunities in biomedical diagnostics, drug delivery systems, smart materials, and real-time drug-release monitoring.
{"title":"Microwave Stripline Probe for Pharmaceutical Hydrogel Swelling Detection","authors":"Shabbir Chowdhury;Amir Ebrahimi;Nazim Nassar;Kamran Ghorbani;Francisco Tovar-Lopez","doi":"10.1109/JERM.2025.3628322","DOIUrl":"https://doi.org/10.1109/JERM.2025.3628322","url":null,"abstract":"This article presents an approach for real-time, non-invasive monitoring of hydrogel swelling dynamics using a microwave probe sensor. A compact stripline probe has been designed to detect dielectric variations caused by water uptake in the pharmaceutical hydrogel APO-Metformin XR 1000. Swelling induces changes in effective permittivity, resulting in a measurable downward shift in the resonance frequency, observed through the input reflection coefficient (<inline-formula><tex-math>$S_{11}$</tex-math></inline-formula>). These frequency shifts can then be processed and used to detect the swelling ratio. The operation principle of the probe, its sensitivity, and the design procedure are explained using an accurate circuit model analysis. A prototype of the probe has been fabricated, and experimental measurements using a pharmaceutical hydrogel were conducted to verify the proposed sensing principle. Controlled experiments under consistent mechanical pressure and hydration conditions demonstrated a correlation between hydrogel swelling ratio and resonance frequency shift, with an exponential decay fit (R<inline-formula><tex-math>$^{2}$</tex-math></inline-formula> = 0.994). Repeatability tests confirmed high measurement stability, with average sensitivity of 90 MHz/g of water absorption. The results highlight the potential of microwave sensing as a sensitive, label-free, and scalable platform for characterizing hydrogel hydration, enabling new opportunities in biomedical diagnostics, drug delivery systems, smart materials, and real-time drug-release monitoring.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":"10 1","pages":"88-98"},"PeriodicalIF":3.2,"publicationDate":"2025-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146223729","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}
This work comprehensively analyses the dependency of voltage transfer gain and magnetoelectric (ME) output voltage coefficient on the encapsulation and geometry of ME laminates. By modulating the internal demagnetizing fields through geometric adjustments, the study demonstrates the capability to effectively tune both the piezoelectric voltage output and the required magnetic bias field. The study systematically investigates the experimental and analytical influence of demagnetizing fields and encapsulation conditions on the ME laminate's voltage output performance. To validate practical applicability, an energy harvesting circuit designed specifically for wearable coil excitation is developed and tested. Measurements of magnetoelectric voltage coefficients are carried out under various conditions—without damping, with encapsulation, and following implantation inside lamb brain tissue—to isolate and quantify their respective impacts on resonance frequency and voltage output. Moreover, this work evaluates the influence of device surface area and internal demagnetising fields on the necessary bias magnetic field, providing crucial insights for optimizing the design towards device miniaturization, that has not been previously investigated. Finally, the harvested energy is successfully rectified to drive a transcranial magnetic stimulation coil, modulated by the internal demagnetising field, and simulations conducted in silico using a quasi-static human phantom head model to underscore the viability and effectiveness of ME further laminates for advanced wearable wireless power transfer technologies.
{"title":"Effect of Demagnetizing Fields and Encapsulation on Wireless Magnetoelectric Output for Medical Devices","authors":"Mahdieh Shojaei Baghini;Mostafa Elsayed;Eve McGlynn;Huxi Wang;Dayhim Nekoeian;Hadi Heidari","doi":"10.1109/JERM.2025.3622953","DOIUrl":"https://doi.org/10.1109/JERM.2025.3622953","url":null,"abstract":"This work comprehensively analyses the dependency of voltage transfer gain and magnetoelectric (ME) output voltage coefficient on the encapsulation and geometry of ME laminates. By modulating the internal demagnetizing fields through geometric adjustments, the study demonstrates the capability to effectively tune both the piezoelectric voltage output and the required magnetic bias field. The study systematically investigates the experimental and analytical influence of demagnetizing fields and encapsulation conditions on the ME laminate's voltage output performance. To validate practical applicability, an energy harvesting circuit designed specifically for wearable coil excitation is developed and tested. Measurements of magnetoelectric voltage coefficients are carried out under various conditions—without damping, with encapsulation, and following implantation inside lamb brain tissue—to isolate and quantify their respective impacts on resonance frequency and voltage output. Moreover, this work evaluates the influence of device surface area and internal demagnetising fields on the necessary bias magnetic field, providing crucial insights for optimizing the design towards device miniaturization, that has not been previously investigated. Finally, the harvested energy is successfully rectified to drive a transcranial magnetic stimulation coil, modulated by the internal demagnetising field, and simulations conducted <italic>in silico</i> using a quasi-static human phantom head model to underscore the viability and effectiveness of ME further laminates for advanced wearable wireless power transfer technologies.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":"10 1","pages":"79-87"},"PeriodicalIF":3.2,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146223595","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 : 2025-10-27DOI: 10.1109/JERM.2025.3620830
Chao Ju;Changrong Liu
Passive LC sensors play an important role in many applications. In time-domain testing, the coupled signal appears quickly after the energizing signal ends and dissipates rapidly. To minimize the impact of switching transients on the testing response time when transitioning between energizing and coupling modes, this paper proposes a reconfigurable impedance matching technique to adjust the resonant frequency of the readout coil. This technique can reduce switching transients and enhance the readout distance of passive LC sensors. Furthermore, forward differentiation is proposed to calculate the resonance frequency, by approximating it with the midpoint of the maximum absolute values of the positive and negative slopes, thereby minimizing measurement errors. Measurements show that it is feasible to dynamically change the self-resonant frequency and Q of the reading coil, and the impact of this change can be reduced by filtering with a band-pass filter. This solution can minimize the time gap between energizing and coupling modes. The measured reading distance can reach 3 cm in the minced pork when using a small-size (13 × 3.5 mm2) LC sensor with a low Q factor (Q = 8).
{"title":"A Readout System With Reduced Switching Transients for Wireless Passive Implantable LC Sensors","authors":"Chao Ju;Changrong Liu","doi":"10.1109/JERM.2025.3620830","DOIUrl":"https://doi.org/10.1109/JERM.2025.3620830","url":null,"abstract":"Passive LC sensors play an important role in many applications. In time-domain testing, the coupled signal appears quickly after the energizing signal ends and dissipates rapidly. To minimize the impact of switching transients on the testing response time when transitioning between energizing and coupling modes, this paper proposes a reconfigurable impedance matching technique to adjust the resonant frequency of the readout coil. This technique can reduce switching transients and enhance the readout distance of passive LC sensors. Furthermore, forward differentiation is proposed to calculate the resonance frequency, by approximating it with the midpoint of the maximum absolute values of the positive and negative slopes, thereby minimizing measurement errors. Measurements show that it is feasible to dynamically change the self-resonant frequency and Q of the reading coil, and the impact of this change can be reduced by filtering with a band-pass filter. This solution can minimize the time gap between energizing and coupling modes. The measured reading distance can reach 3 cm in the minced pork when using a small-size (13 × 3.5 mm<sup>2</sup>) LC sensor with a low Q factor (Q = 8).","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":"10 1","pages":"70-78"},"PeriodicalIF":3.2,"publicationDate":"2025-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146223686","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 : 2025-10-10DOI: 10.1109/JERM.2025.3611870
Allyanna Rice;M Shifatul Islam;Asimina Kiourti
Microwave sensing devices have the potential to be a non-ionizing, low-cost, and portable solution for monitoring osteoporosis. However, existing microwave sensors suffer from weak transmission into the tissues, small signal variation over different degrees of osteoporosis, and small bandwidth. In this work, we overcome challenges in the state-of-the-art by proposing a microwave-based sensing technique where two into-body antennas (specifically, high-contrast low-loss antennas, or HCLAs) are placed on either side of the wrist to monitor osteoporotic conditions. As a proof-of-concept, we first perform simulations and experiments over planar, layered structures, consisting of bone-only and 2/3 muscle-bone layers. To further assess performance in realistic scenarios, we perform full-wave simulations using a human arm voxel model. We use two bone volume fraction (BVF) models to quantify osteoporosis; where 10% and 40% BVF suggest osteoporotic and healthy bone, respectively. A unit cell analysis over the planar layered geometries indicates that HCLA transmission is very efficient, with only $approx 5$ dB lower transmission than the theoretically possible best values for frequencies $>2$ GHz. The dynamic range (i.e., change in signal between healthy and osteoporotic bone) of the transmission coefficient magnitude and phase is $ approx 2$ dB and and $ approx 70 ^circ$ near 4 GHz, respectively. Voxel simulations show an irregular, yet considerable dynamic range of $approx 8$ dB and $100 ^ circ$, respectively. Strong signal levels, large dynamic range over a wide bandwidth, and a small form factor suggest that HCLA measurements, when also combined in the future with appropriate calibration and post-processing, can be used as an efficient method to monitor osteoporosis.
{"title":"Monitoring Osteoporosis With Into-Body Antennas: A Feasibility Study","authors":"Allyanna Rice;M Shifatul Islam;Asimina Kiourti","doi":"10.1109/JERM.2025.3611870","DOIUrl":"https://doi.org/10.1109/JERM.2025.3611870","url":null,"abstract":"Microwave sensing devices have the potential to be a non-ionizing, low-cost, and portable solution for monitoring osteoporosis. However, existing microwave sensors suffer from weak transmission into the tissues, small signal variation over different degrees of osteoporosis, and small bandwidth. In this work, we overcome challenges in the state-of-the-art by proposing a microwave-based sensing technique where two into-body antennas (specifically, high-contrast low-loss antennas, or HCLAs) are placed on either side of the wrist to monitor osteoporotic conditions. As a proof-of-concept, we first perform simulations and experiments over planar, layered structures, consisting of bone-only and 2/3 muscle-bone layers. To further assess performance in realistic scenarios, we perform full-wave simulations using a human arm voxel model. We use two bone volume fraction (BVF) models to quantify osteoporosis; where 10% and 40% BVF suggest osteoporotic and healthy bone, respectively. A unit cell analysis over the planar layered geometries indicates that HCLA transmission is very efficient, with only <inline-formula><tex-math>$approx 5$</tex-math></inline-formula> dB lower transmission than the theoretically possible best values for frequencies <inline-formula><tex-math>$>2$</tex-math></inline-formula> GHz. The dynamic range (i.e., change in signal between healthy and osteoporotic bone) of the transmission coefficient magnitude and phase is <inline-formula><tex-math>$ approx 2$</tex-math></inline-formula> dB and and <inline-formula><tex-math>$ approx 70 ^circ$</tex-math></inline-formula> near 4 GHz, respectively. Voxel simulations show an irregular, yet considerable dynamic range of <inline-formula><tex-math>$approx 8$</tex-math></inline-formula> dB and <inline-formula><tex-math>$100 ^ circ$</tex-math></inline-formula>, respectively. Strong signal levels, large dynamic range over a wide bandwidth, and a small form factor suggest that HCLA measurements, when also combined in the future with appropriate calibration and post-processing, can be used as an efficient method to monitor osteoporosis.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":"10 1","pages":"45-52"},"PeriodicalIF":3.2,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146223685","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 : 2025-09-26DOI: 10.1109/JERM.2025.3611942
L. Guo;N. Nguyen-Trong;S. Ahdi Rezaeieh;SM-Hadi Mousavi;A. Abbosh
With the rapid development of medical microwave imaging systems, their accurate simulation becomes important to ensure the reliability of the developed hardware and software before moving to clinical tests. This is particularly important when using machine learning techniques that require a large volume of simulated data for training. Since the target responses in medical microwave imaging are quite weak, the numerical errors and variations caused by different meshing used in numerical simulations most likely mask the target response; thus, interfering with the pattern of the simulated dataset and resulting in misleading results. Since most available bio-models are voxel-based and can only be meshed using hexahedra, this article focuses on time-domain solvers that use hexahedral meshing. It investigates numerical modeling errors caused by mesh variations in realistic three-dimensional (3D) simulations, their impact on data distribution for machine learning algorithms, and the trade-off between convergence and total simulation time. A realistic 3D microwave head imaging system is used as an example. A delta-simulation approach is presented to eliminate data variations in the constructed dataset caused by inconsistent mesh distributions across simulated cases. The kernel principal component analysis and k-means clustering techniques are used to evaluate the proposed approach. The assessments show that the proposed delta-simulation method can generate a dataset with a more informative data distribution, thereby facilitating subsequent machine learning algorithms. In addition, the delta-simulation balances accuracy and efficiency by maintaining an acceptable number of mesh elements that can be simulated in a reasonable time.
{"title":"Mitigating Mesh-Induced Errors in Time-Domain Simulation of Medical Microwave Imaging","authors":"L. Guo;N. Nguyen-Trong;S. Ahdi Rezaeieh;SM-Hadi Mousavi;A. Abbosh","doi":"10.1109/JERM.2025.3611942","DOIUrl":"https://doi.org/10.1109/JERM.2025.3611942","url":null,"abstract":"With the rapid development of medical microwave imaging systems, their accurate simulation becomes important to ensure the reliability of the developed hardware and software before moving to clinical tests. This is particularly important when using machine learning techniques that require a large volume of simulated data for training. Since the target responses in medical microwave imaging are quite weak, the numerical errors and variations caused by different meshing used in numerical simulations most likely mask the target response; thus, interfering with the pattern of the simulated dataset and resulting in misleading results. Since most available bio-models are voxel-based and can only be meshed using hexahedra, this article focuses on time-domain solvers that use hexahedral meshing. It investigates numerical modeling errors caused by mesh variations in realistic three-dimensional (3D) simulations, their impact on data distribution for machine learning algorithms, and the trade-off between convergence and total simulation time. A realistic 3D microwave head imaging system is used as an example. A delta-simulation approach is presented to eliminate data variations in the constructed dataset caused by inconsistent mesh distributions across simulated cases. The kernel principal component analysis and k-means clustering techniques are used to evaluate the proposed approach. The assessments show that the proposed delta-simulation method can generate a dataset with a more informative data distribution, thereby facilitating subsequent machine learning algorithms. In addition, the delta-simulation balances accuracy and efficiency by maintaining an acceptable number of mesh elements that can be simulated in a reasonable time.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":"10 1","pages":"25-34"},"PeriodicalIF":3.2,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146223742","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 : 2025-09-26DOI: 10.1109/JERM.2025.3610697
Md Shahriar;Kaisari Ferdous;Sourav Kumar Pramanik;Shekh M. M. Islam
Objectives: Non-contact and continuous respiratory monitoring is vital for detecting health risks such as sleep apnea, cardiac events, and respiratory disorders. Non-contact methods using Radar offer an unobtrusive solution but face challenges when multiple subjects and varied sleep postures are involved. Technology or Method: This study presents a novel non-contact dual-subject respiratory monitoring framework using a 24-GHz continuous-wave (CW) radar combined with Independent Component Analysis-Joint Approximate Diagonalization of Eigenmatrices (ICA-JADE) for isolating individual respiratory patterns from the combined mixtures and maximal overlap discrete wavelet transform (MODWT) for subharmonics compression. To our knowledge, this is the first reported investigation to recognize concurrent respiratory patterns of dual subjects across sleep postures using CW radar. Results: Respiratory signals from five groups of two concurrent subjects (10 subjects total) were successfully separated using ICA-JADE and classified into normal, fast, and slow breathing patterns across supine, side, and prone sleep postures. The system achieved consistently high classification accuracies across postures for normal breathing, with an average accuracy exceeding 90%. Fast breathing patterns were also classified with high accuracy but showed slightly more variability across postures. Slow breathing patterns, particularly in the prone posture, were more challenging to classify due to reduced respiratory displacement and subharmonic interference, leading to an initial accuracy drop to 76.68%. Application of Maximal Overlap Discrete Wavelet Transform (MODWT) enhanced slow breathing signal quality, improving prone posture classification to 85.14%. Across all breathing patterns and postures, the proposed method achieved a maximum overall classification accuracy of 88.48%. Clinical or Biological Impact: This technology paves the way for non-contact, privacy-preserving, continuous respiratory monitoring in sleep studies, intensive care, and home healthcare, with the potential to detect early signs of respiratory and sleep disorders without reliance on wearables.
{"title":"Non-Contact Monitoring and Recognition of Varied Respiratory Patterns From Dual-Subject Across Sleep Postures Using CW Radar","authors":"Md Shahriar;Kaisari Ferdous;Sourav Kumar Pramanik;Shekh M. M. Islam","doi":"10.1109/JERM.2025.3610697","DOIUrl":"https://doi.org/10.1109/JERM.2025.3610697","url":null,"abstract":"<italic>Objectives:</i> Non-contact and continuous respiratory monitoring is vital for detecting health risks such as sleep apnea, cardiac events, and respiratory disorders. Non-contact methods using Radar offer an unobtrusive solution but face challenges when multiple subjects and varied sleep postures are involved. <italic>Technology or Method:</i> This study presents a novel non-contact dual-subject respiratory monitoring framework using a 24-GHz continuous-wave (CW) radar combined with Independent Component Analysis-Joint Approximate Diagonalization of Eigenmatrices (ICA-JADE) for isolating individual respiratory patterns from the combined mixtures and maximal overlap discrete wavelet transform (MODWT) for subharmonics compression. To our knowledge, this is the first reported investigation to recognize concurrent respiratory patterns of dual subjects across sleep postures using CW radar. <italic>Results:</i> Respiratory signals from five groups of two concurrent subjects (10 subjects total) were successfully separated using ICA-JADE and classified into normal, fast, and slow breathing patterns across supine, side, and prone sleep postures. The system achieved consistently high classification accuracies across postures for normal breathing, with an average accuracy exceeding 90%. Fast breathing patterns were also classified with high accuracy but showed slightly more variability across postures. Slow breathing patterns, particularly in the prone posture, were more challenging to classify due to reduced respiratory displacement and subharmonic interference, leading to an initial accuracy drop to 76.68%. Application of Maximal Overlap Discrete Wavelet Transform (MODWT) enhanced slow breathing signal quality, improving prone posture classification to 85.14%. Across all breathing patterns and postures, the proposed method achieved a maximum overall classification accuracy of 88.48%. <italic>Clinical or Biological Impact:</i> This technology paves the way for non-contact, privacy-preserving, continuous respiratory monitoring in sleep studies, intensive care, and home healthcare, with the potential to detect early signs of respiratory and sleep disorders without reliance on wearables.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":"10 1","pages":"35-44"},"PeriodicalIF":3.2,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146223760","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 : 2025-09-17DOI: 10.1109/JERM.2025.3604080
Francesco Lestini;Gaetano Marrocco;Cecilia Occhiuzzi
Implantable Medical Devices (IMDs) such as pacemakers and defibrillators increasingly rely on wireless connectivity for remote monitoring and programming. However, this wireless access introduces significant cybersecurity and physical vulnerabilities, making IMDs susceptible to unauthorized access and electromagnetic interference (EMI). This paper proposes a wirelessly programmable smart shield based on a reconfigurable Frequency Selective Surface (P-FSS) as a novel defense mechanism for IMD security. The shield dynamically transitions between shielding and transparency states, passively controlled by an RFID-powered circuit, ensuring protection from malicious attacks while enabling authorized medical communication. This study extends prior theoretical investigations by introducing a fully functional prototype, realized with a rigorous design methodology and leveraging low-power varactor-based switching to enhance efficiency and miniaturize the size. The system demonstrates over 40 dB of shielding effectiveness in the Medical Implant Communication Service (MICS) band (401–406 MHz) while allowing controlled transparency via a battery-less RFID interface with an activation distance of 0.6 m. Experimental validation confirms the practical feasibility of the proposed approach, making it a viable solution for enhancing the cyber-physical security of IMDs.
{"title":"Passive Wireless Programmable FSS for Adaptive Electromagnetic Shielding of Implanted Medical Devices","authors":"Francesco Lestini;Gaetano Marrocco;Cecilia Occhiuzzi","doi":"10.1109/JERM.2025.3604080","DOIUrl":"https://doi.org/10.1109/JERM.2025.3604080","url":null,"abstract":"Implantable Medical Devices (IMDs) such as pacemakers and defibrillators increasingly rely on wireless connectivity for remote monitoring and programming. However, this wireless access introduces significant cybersecurity and physical vulnerabilities, making IMDs susceptible to unauthorized access and electromagnetic interference (EMI). This paper proposes a wirelessly programmable smart shield based on a reconfigurable Frequency Selective Surface (P-FSS) as a novel defense mechanism for IMD security. The shield dynamically transitions between shielding and transparency states, passively controlled by an RFID-powered circuit, ensuring protection from malicious attacks while enabling authorized medical communication. This study extends prior theoretical investigations by introducing a fully functional prototype, realized with a rigorous design methodology and leveraging low-power varactor-based switching to enhance efficiency and miniaturize the size. The system demonstrates over 40 dB of shielding effectiveness in the Medical Implant Communication Service (MICS) band (401–406 MHz) while allowing controlled transparency via a battery-less RFID interface with an activation distance of 0.6 m. Experimental validation confirms the practical feasibility of the proposed approach, making it a viable solution for enhancing the cyber-physical security of IMDs.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":"10 1","pages":"14-24"},"PeriodicalIF":3.2,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146223730","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}
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