Pub Date : 2023-08-14DOI: 10.1109/JERM.2023.3298730
Marco Mercuri;Emilio Arnieri;Raffaele De Marco;Pierangelo Veltri;Felice Crupi;Luigi Boccia
The application of radar technology in indoor people monitoring has opened up new avenues, such as localization and tracking, vital signs monitoring, and fall detection. Nevertheless, one of the significant challenges facing radar systems is the issue of indoor multipath propagation, which results in radar ghosts that can diminish the detection accuracy or even compromise the monitoring process entirely. This study delves into the utilization of reconfigurable intelligent surfaces (RISs) in radar-based indoor people localization. Thanks to the use of RIS, targets can be tracked from multiple orientations, achieving a more precise estimation of the propagation channel and in turn mitigating the effects of indoor multipath propagation. As a result, the detection performance of the radar system can be improved without increasing the radar's complexity. Empirical evidence gathered from experiments conducted in a laboratory environment has demonstrated the feasibility of the proposed approach in accurately locating multiple subjects in a two-dimensional (2-D) space while being able to reject radar ghosts. Practical implications of this novel approach include the development of smart building systems, Internet of Things (IoT), telemedicine, Hospital 4.0, automated nurse call solutions, ambient assisted living, firefighter tracking, and security applications.
{"title":"Reconfigurable Intelligent Surface-Aided Indoor Radar Monitoring: A Feasibility Study","authors":"Marco Mercuri;Emilio Arnieri;Raffaele De Marco;Pierangelo Veltri;Felice Crupi;Luigi Boccia","doi":"10.1109/JERM.2023.3298730","DOIUrl":"10.1109/JERM.2023.3298730","url":null,"abstract":"The application of radar technology in indoor people monitoring has opened up new avenues, such as localization and tracking, vital signs monitoring, and fall detection. Nevertheless, one of the significant challenges facing radar systems is the issue of indoor multipath propagation, which results in radar ghosts that can diminish the detection accuracy or even compromise the monitoring process entirely. This study delves into the utilization of reconfigurable intelligent surfaces (RISs) in radar-based indoor people localization. Thanks to the use of RIS, targets can be tracked from multiple orientations, achieving a more precise estimation of the propagation channel and in turn mitigating the effects of indoor multipath propagation. As a result, the detection performance of the radar system can be improved without increasing the radar's complexity. Empirical evidence gathered from experiments conducted in a laboratory environment has demonstrated the feasibility of the proposed approach in accurately locating multiple subjects in a two-dimensional (2-D) space while being able to reject radar ghosts. Practical implications of this novel approach include the development of smart building systems, Internet of Things (IoT), telemedicine, Hospital 4.0, automated nurse call solutions, ambient assisted living, firefighter tracking, and security applications.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2023-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136116504","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 : 2023-08-08DOI: 10.1109/JERM.2023.3299525
Francesco Lestini;Nicoletta Panunzio;Gaetano Marrocco;Cecilia Occhiuzzi
Hyperthermia is an anti-cancer treatment that exploits the interaction between high-power electromagnetic fields and restricted regions of human tissues releasing a great amount of power to locally increase tissues temperature. Due to the high power, dangerous hot-spots may occur on the skin so that continuous monitoring of superficial temperature distribution is required. Thermal Monitoring Sheets (TMSs), which are grids of several wired temperature sensors, are currently used in clinical practice; however, they have some limitations in terms of poor spatial resolution, thermal conduction errors, and complex application procedures. Epidermal electronics associated with passive Ultra High Frequency (UHF) Radio Frequency IDentification (RFID) sensing technology could represent an attractive alternative thanks to its wireless nature and limited invasiveness. In this framework, this article proposes an innovative TMS based on battery-less RFID sensors (R-TMS). It comprises a planar grid of circular loop antennas with temperature-sensing-oriented ICs that can sample skin temperature without interfering with hyperthermia treatment. The system proved capable of monitoring skin temperature via wireless data transmission with a higher spatial resolution that state-of-the-art devices. The physical rationale, the design, and the experimentation of the R-TMS are here presented to validate the proposed approach and evaluate its feasibility from the electromagnetic perspective.
{"title":"Epidermal RFID-Based Thermal Monitoring Sheet (R-TMS) for Microwave Hyperthermia","authors":"Francesco Lestini;Nicoletta Panunzio;Gaetano Marrocco;Cecilia Occhiuzzi","doi":"10.1109/JERM.2023.3299525","DOIUrl":"10.1109/JERM.2023.3299525","url":null,"abstract":"Hyperthermia is an anti-cancer treatment that exploits the interaction between high-power electromagnetic fields and restricted regions of human tissues releasing a great amount of power to locally increase tissues temperature. Due to the high power, dangerous hot-spots may occur on the skin so that continuous monitoring of superficial temperature distribution is required. Thermal Monitoring Sheets (TMSs), which are grids of several wired temperature sensors, are currently used in clinical practice; however, they have some limitations in terms of poor spatial resolution, thermal conduction errors, and complex application procedures. Epidermal electronics associated with passive Ultra High Frequency (UHF) Radio Frequency IDentification (RFID) sensing technology could represent an attractive alternative thanks to its wireless nature and limited invasiveness. In this framework, this article proposes an innovative TMS based on battery-less RFID sensors (R-TMS). It comprises a planar grid of circular loop antennas with temperature-sensing-oriented ICs that can sample skin temperature without interfering with hyperthermia treatment. The system proved capable of monitoring skin temperature via wireless data transmission with a higher spatial resolution that state-of-the-art devices. The physical rationale, the design, and the experimentation of the R-TMS are here presented to validate the proposed approach and evaluate its feasibility from the electromagnetic perspective.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2023-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88397618","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 : 2023-07-28DOI: 10.1109/JERM.2023.3294707
Muhammad Solihin Zulkefli;Kai Zhang;Mariella Sarestoniemi;Sami Myllymäki;William G. Whittow;Sen Yan;Ping Jack Soh
An experimental wireless link and specific absorption rate (SAR) assessment is presented in this work. A compact planar inverted-F antenna (PIFA) is designed and evaluated for biotelemetry application as an antenna at 2.45 GHz band. The proposed antenna provided a satisfactory bandwidth per unit volume using a two-layered stacked structure consisting of a high-frequency laminate and a low loss ceramic layer. The antenna was first co-designed inside several different types of phantom boxes to optimize its performance, considering computational resources. Next, a semisolid intestinal phantom model used in simulations were chosen to be fabricated for experimental evaluations. Evaluation results indicated a satisfactory antenna's operation from 2.13 to 2.81 GHz (bandwidth of 27.8%), with realized gains of −26.49 dBi when implanted at 45 mm inside the phantom. Next, measurements were performed on the antenna's communication link with a wearable antenna to study the effects its depth (from 10 to 45mm), indicating transmission coefficients of between −40 and −60 dB at 2.45 GHz. Finally, its SAR levels are evaluated experimentally using a commercial measurement system when implanted within the human tissue. Results indicated satisfactory level of 0.685 W/kg (averaged over 10 g of tissues) and is suitable for biotelemetry application.
{"title":"Experimental Wireless Link and SAR Assessments of an Implantable PIFA for Biotelemetry in the 2.45 GHz Band","authors":"Muhammad Solihin Zulkefli;Kai Zhang;Mariella Sarestoniemi;Sami Myllymäki;William G. Whittow;Sen Yan;Ping Jack Soh","doi":"10.1109/JERM.2023.3294707","DOIUrl":"https://doi.org/10.1109/JERM.2023.3294707","url":null,"abstract":"An experimental wireless link and specific absorption rate (SAR) assessment is presented in this work. A compact planar inverted-F antenna (PIFA) is designed and evaluated for biotelemetry application as an antenna at 2.45 GHz band. The proposed antenna provided a satisfactory bandwidth per unit volume using a two-layered stacked structure consisting of a high-frequency laminate and a low loss ceramic layer. The antenna was first co-designed inside several different types of phantom boxes to optimize its performance, considering computational resources. Next, a semisolid intestinal phantom model used in simulations were chosen to be fabricated for experimental evaluations. Evaluation results indicated a satisfactory antenna's operation from 2.13 to 2.81 GHz (bandwidth of 27.8%), with realized gains of −26.49 dBi when implanted at 45 mm inside the phantom. Next, measurements were performed on the antenna's communication link with a wearable antenna to study the effects its depth (from 10 to 45mm), indicating transmission coefficients of between −40 and −60 dB at 2.45 GHz. Finally, its SAR levels are evaluated experimentally using a commercial measurement system when implanted within the human tissue. Results indicated satisfactory level of 0.685 W/kg (averaged over 10 g of tissues) and is suitable for biotelemetry application.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2023-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50291935","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}
In this article, an explainable deep learning scheme is proposed to tackle microwave imaging for the task of multiple object localisation. Deep learning has been involved in solving microwave imaging tasks due to its strong pattern recognition capabilities. However, the lack of explainability of the model's predictions makes it infeasible to deploy deep learning models in practical applications such as stroke detection and localisation as the model is a black box, the confidence of the output is unknown as they cannot be verified. This article aims to alleviate this concern by applying the gradient-weighted class activation map (Grad-CAM), an explainable artificial intelligence technique, together with the Delay-Multiply-And-Sum (DMAS) algorithm to spatially explain the deep learning model. The Grad-CAM method highlights the important parts of the input signal for decision making and the important parts are mapped to the image domain to provide a more intuitive understanding of the model. This article concludes that the deep learning model learns from reliable information and provides outputs which have a physical basis.
{"title":"An Explainable Deep Learning Method for Microwave Head Stroke Localization","authors":"Wei-chung Lai;Lei Guo;Konstanty Bialkowski;Alina Bialkowski","doi":"10.1109/JERM.2023.3287681","DOIUrl":"10.1109/JERM.2023.3287681","url":null,"abstract":"In this article, an explainable deep learning scheme is proposed to tackle microwave imaging for the task of multiple object localisation. Deep learning has been involved in solving microwave imaging tasks due to its strong pattern recognition capabilities. However, the lack of explainability of the model's predictions makes it infeasible to deploy deep learning models in practical applications such as stroke detection and localisation as the model is a black box, the confidence of the output is unknown as they cannot be verified. This article aims to alleviate this concern by applying the gradient-weighted class activation map (Grad-CAM), an explainable artificial intelligence technique, together with the Delay-Multiply-And-Sum (DMAS) algorithm to spatially explain the deep learning model. The Grad-CAM method highlights the important parts of the input signal for decision making and the important parts are mapped to the image domain to provide a more intuitive understanding of the model. This article concludes that the deep learning model learns from reliable information and provides outputs which have a physical basis.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2023-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75084701","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 : 2023-07-06DOI: 10.1109/JERM.2023.3289767
Douglas J. Kurrant;Muhammad Omer;Elise C. Fear
The emergence and subsequent expansion of the field of medical microwave imaging has resulted in numerous approaches to image reconstruction. This includes microwave tomography, radar imaging, and more recently, multi-modality approaches. However, there is an absence of a standardized and widely accepted process that is proficient at extracting information from these images and employing this knowledge to conduct a thorough quantitative evaluation of images and regions within images. This shortcoming may interfere with a researcher's ability to make reliable and consistent inferences from experiments and to interpret results. Consequently, comparing the results of different research groups is difficult. This is becoming increasingly relevant due to the development of standardized test phantoms and the increase in clinical studies. To remedy this deficiency, an automated workflow has been developed with the objective to standardize the processing and analysis of images acquired from a range of modalities. Images are first segmented into regions dominated by a tissue type. Quantitative information extracted from these regions is used for analysis and by visualization tools for the qualitative interpretation of images. The effectiveness of the workflow is demonstrated with multiple examples that focus on quantifying changes to images due to enhancements of the reconstruction algorithm or perturbations of a parameter used by the reconstruction operator.
{"title":"Automated Workflow for Evaluating Microwave and Multi-Modality Breast Images","authors":"Douglas J. Kurrant;Muhammad Omer;Elise C. Fear","doi":"10.1109/JERM.2023.3289767","DOIUrl":"https://doi.org/10.1109/JERM.2023.3289767","url":null,"abstract":"The emergence and subsequent expansion of the field of medical microwave imaging has resulted in numerous approaches to image reconstruction. This includes microwave tomography, radar imaging, and more recently, multi-modality approaches. However, there is an absence of a standardized and widely accepted process that is proficient at extracting information from these images and employing this knowledge to conduct a thorough quantitative evaluation of images and regions within images. This shortcoming may interfere with a researcher's ability to make reliable and consistent inferences from experiments and to interpret results. Consequently, comparing the results of different research groups is difficult. This is becoming increasingly relevant due to the development of standardized test phantoms and the increase in clinical studies. To remedy this deficiency, an automated workflow has been developed with the objective to standardize the processing and analysis of images acquired from a range of modalities. Images are first segmented into regions dominated by a tissue type. Quantitative information extracted from these regions is used for analysis and by visualization tools for the qualitative interpretation of images. The effectiveness of the workflow is demonstrated with multiple examples that focus on quantifying changes to images due to enhancements of the reconstruction algorithm or perturbations of a parameter used by the reconstruction operator.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2023-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50291936","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 : 2023-07-03DOI: 10.1109/JERM.2023.3288741
Matteo Bruno Lodi;Nicola Curreli;Chiara Dachena;Alessandro Fedeli;Rosa Scapaticci;Andrea Randazzo;Matteo Pastorino;Alessandro Fanti
Magnetic biomaterials are multifunctional tools currently under investigation as theranostic platforms for biomedical applications. They can be implanted in bone tissue after bone cancer resection to perform local interstitial hyperthermia treatment. Given the requirements of high quality treatment, the hyperthermia therapy should be performed monitoring the system temperature, to avoid hot spots and control the treatment outcome. It is known that the magnetic properties of such implants vary with temperature. It is hypotesized that the treatment dynamic could be monitored using a microwave monitoring system. The variation of the electromagnetic properties of the biological tissues and the magnetic implant during the therapy would result in a different propagation of the microwave signal. This work investigates the feasibility of using microwaves to non-invasively monitor hyperthermia treatments with a simplified monodimensional propagation model. The forward problem is solved to identify the working frequencies, the matching medium properties and study several candidate materials. By using the numerical solutions from nonlinear and multiphysics simulations of the bone tumor hyperthermia treatment using magnetic scaffolds, the microwave signal propagation dynamic is studied. From our feasibility analysis, we found that it is possible to correlate the average tumor temperature with significant ( $sim$ 20 dB) variations in the transmission coefficient during a typical interstitial hyperthermia session using magnetic scaffolds. Our work brings together, for the first time, the electromagnetic material properties, the physio-pathology and physics of the hyperthermia treatment and the microwave propagation problem, thus paving the route for the development of an innovative theranostic system.
{"title":"Feasibility Analysis of Theranostic Magnetic Scaffolds for Microwave Monitoring of Hyperthermia Treatment of Bone Tumors","authors":"Matteo Bruno Lodi;Nicola Curreli;Chiara Dachena;Alessandro Fedeli;Rosa Scapaticci;Andrea Randazzo;Matteo Pastorino;Alessandro Fanti","doi":"10.1109/JERM.2023.3288741","DOIUrl":"10.1109/JERM.2023.3288741","url":null,"abstract":"Magnetic biomaterials are multifunctional tools currently under investigation as theranostic platforms for biomedical applications. They can be implanted in bone tissue after bone cancer resection to perform local interstitial hyperthermia treatment. Given the requirements of high quality treatment, the hyperthermia therapy should be performed monitoring the system temperature, to avoid hot spots and control the treatment outcome. It is known that the magnetic properties of such implants vary with temperature. It is hypotesized that the treatment dynamic could be monitored using a microwave monitoring system. The variation of the electromagnetic properties of the biological tissues and the magnetic implant during the therapy would result in a different propagation of the microwave signal. This work investigates the feasibility of using microwaves to non-invasively monitor hyperthermia treatments with a simplified monodimensional propagation model. The forward problem is solved to identify the working frequencies, the matching medium properties and study several candidate materials. By using the numerical solutions from nonlinear and multiphysics simulations of the bone tumor hyperthermia treatment using magnetic scaffolds, the microwave signal propagation dynamic is studied. From our feasibility analysis, we found that it is possible to correlate the average tumor temperature with significant (\u0000<inline-formula><tex-math>$sim$</tex-math></inline-formula>\u000020 dB) variations in the transmission coefficient during a typical interstitial hyperthermia session using magnetic scaffolds. Our work brings together, for the first time, the electromagnetic material properties, the physio-pathology and physics of the hyperthermia treatment and the microwave propagation problem, thus paving the route for the development of an innovative theranostic system.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2023-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10172102","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77804967","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 : 2023-07-03DOI: 10.1109/JERM.2023.3285049
Jacob T. Pawlik;Nikolas D. Barrera;Eugene J. Yoon;James C. Booth;Christian J. Long;Nathan D. Orloff;Ellis Meng;Angela C. Stelson
Parylene C is a widely used dielectric barrier in implantable medical devices because it conforms well to surfaces and insulates against biological environments. However, multiple studies have shown that moisture can intrude into Parylene C films through defects and intrinsic diffusion, leading to delamination and device failure. While many studies have tested device integrity in vitro, few have isolated the influence of specific degradation mechanisms on device failure. Here, we use a broadband impedance technique called Microwave Microfluidic Spectroscopy (MMS) to measure fluid permeation in targeted regions of Parylene C films that are free of defects and have optimal adhesion to the substrate. We found no changes in the broadband S-parameters from 100 MHz–110 GHz for Parylene C coated coplanar waveguides soaked in water or phosphate buffered saline at 20 °C or 37 °C for two months. Furthermore, there was no delamination induced by fluid soaking. Our study helps to clear debate about the influence of water and ion diffusion on Parylene C device lifetime and inform better fabrication of Parylene C coatings for implantable devices.
{"title":"The Influence of Intrinsic Water and Ion Permeation on the Dielectric Properties of Parylene C Films","authors":"Jacob T. Pawlik;Nikolas D. Barrera;Eugene J. Yoon;James C. Booth;Christian J. Long;Nathan D. Orloff;Ellis Meng;Angela C. Stelson","doi":"10.1109/JERM.2023.3285049","DOIUrl":"10.1109/JERM.2023.3285049","url":null,"abstract":"Parylene C is a widely used dielectric barrier in implantable medical devices because it conforms well to surfaces and insulates against biological environments. However, multiple studies have shown that moisture can intrude into Parylene C films through defects and intrinsic diffusion, leading to delamination and device failure. While many studies have tested device integrity in vitro, few have isolated the influence of specific degradation mechanisms on device failure. Here, we use a broadband impedance technique called Microwave Microfluidic Spectroscopy (MMS) to measure fluid permeation in targeted regions of Parylene C films that are free of defects and have optimal adhesion to the substrate. We found no changes in the broadband S-parameters from 100 MHz–110 GHz for Parylene C coated coplanar waveguides soaked in water or phosphate buffered saline at 20 °C or 37 °C for two months. Furthermore, there was no delamination induced by fluid soaking. Our study helps to clear debate about the influence of water and ion diffusion on Parylene C device lifetime and inform better fabrication of Parylene C coatings for implantable devices.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2023-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72592318","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 : 2023-06-30DOI: 10.1109/JERM.2023.3289155
Peter M. Asbeck;Sravya Alluri;Vincent Leung;Shaghayegh Abbasi;Milan T. Makale
Pulse stimulation of peripheral nerves (PNS) is extensively used in the diagnosis of nerve abnormalities and can be applied for pain mitigation and to promote nerve regrowth. Nerve stimulation via magnetic pulses can provide advantages over conventional electrical stimulation; it obviates the need for electrode contact with the skin and is typically less painful. This work contributes to the development of compact and portable systems for magnetic PNS (M-PNS). To date, M-PNS has largely employed pulse generation systems developed for repetitive transcranial magnetic stimulation (rTMS). A new circuit is demonstrated to generate pulsed magnetic fields that increases induced electric (E) field intensities over those attainable in conventional rTMS systems. The resultant E-field has a shortened duration. The required external voltage input is below 300 V. A compact circuit implementation produced peak E-fields of 280 V/m at 1.5 cm distance from the magnetic coil, in 23 μs pulses (while 70-280 μs pulses are typically used for rTMS). Although threshold E fields for neural excitation increase with shorter pulse widths, neural excitation is demonstrated in human subjects via ulnar nerve stimulation and electromyography. This circuit technique may facilitate greater feasibility and flexibility in the design of miniaturized and portable PNS medical devices.
{"title":"An Efficient Circuit for Pulsed Magnetic Neural Stimulation","authors":"Peter M. Asbeck;Sravya Alluri;Vincent Leung;Shaghayegh Abbasi;Milan T. Makale","doi":"10.1109/JERM.2023.3289155","DOIUrl":"https://doi.org/10.1109/JERM.2023.3289155","url":null,"abstract":"Pulse stimulation of peripheral nerves (PNS) is extensively used in the diagnosis of nerve abnormalities and can be applied for pain mitigation and to promote nerve regrowth. Nerve stimulation via magnetic pulses can provide advantages over conventional electrical stimulation; it obviates the need for electrode contact with the skin and is typically less painful. This work contributes to the development of compact and portable systems for magnetic PNS (M-PNS). To date, M-PNS has largely employed pulse generation systems developed for repetitive transcranial magnetic stimulation (rTMS). A new circuit is demonstrated to generate pulsed magnetic fields that increases induced electric (E) field intensities over those attainable in conventional rTMS systems. The resultant E-field has a shortened duration. The required external voltage input is below 300 V. A compact circuit implementation produced peak E-fields of 280 V/m at 1.5 cm distance from the magnetic coil, in 23 μs pulses (while 70-280 μs pulses are typically used for rTMS). Although threshold E fields for neural excitation increase with shorter pulse widths, neural excitation is demonstrated in human subjects via ulnar nerve stimulation and electromyography. This circuit technique may facilitate greater feasibility and flexibility in the design of miniaturized and portable PNS medical devices.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50404732","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}
In recent years, cerebrovascular disease has become one of the leading causes of death among Chinese residents. Early detection of brain disease is, therefore, of great significance in reducing the risks to life and health. Thermoacoustic imaging has emerged as a promising technique for detecting brain disease, which meets the requirements of high penetration depth and real-time imaging in transcranial imaging. However, the acoustic characteristics of the skull can significantly impact the propagation of thermoacoustic signals, leading to attenuation and apparent phase difference, resulting in poor quality of reconstructed image and location deviation of symptom points. In this study, a skull phase compensated method combined full waveform inversion for transcranial thermoacoustic imaging is proposed. The adaptive positioning of skull is realized firstly by improving the W-AIC algorithm in thermoacoustic imaging to solve the phase difference problem and FWI technology is applied for reconstructing the intracranial SoS distribution. Numerical simulation of a human brain model and actual human skull experiments further verify the feasibility of this method in improving the quality of thermoacoustic images, thereby providing a reliable theoretical basis for the clinical application of transcranial thermoacoustic imaging.
{"title":"Skull Phase Compensation Combined Full Waveform Inversion for Transcranial Thermoacoustic Imaging With a Real Human Skull Validated","authors":"Shuang-Li Liu;Xin Shang;Wan-Ting Peng;Wei-Jia Wan;Jin-Bao Zhang","doi":"10.1109/JERM.2023.3281057","DOIUrl":"10.1109/JERM.2023.3281057","url":null,"abstract":"In recent years, cerebrovascular disease has become one of the leading causes of death among Chinese residents. Early detection of brain disease is, therefore, of great significance in reducing the risks to life and health. Thermoacoustic imaging has emerged as a promising technique for detecting brain disease, which meets the requirements of high penetration depth and real-time imaging in transcranial imaging. However, the acoustic characteristics of the skull can significantly impact the propagation of thermoacoustic signals, leading to attenuation and apparent phase difference, resulting in poor quality of reconstructed image and location deviation of symptom points. In this study, a skull phase compensated method combined full waveform inversion for transcranial thermoacoustic imaging is proposed. The adaptive positioning of skull is realized firstly by improving the W-AIC algorithm in thermoacoustic imaging to solve the phase difference problem and FWI technology is applied for reconstructing the intracranial SoS distribution. Numerical simulation of a human brain model and actual human skull experiments further verify the feasibility of this method in improving the quality of thermoacoustic images, thereby providing a reliable theoretical basis for the clinical application of transcranial thermoacoustic imaging.","PeriodicalId":29955,"journal":{"name":"IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2023-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75290361","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 : 2023-06-07DOI: 10.1109/JERM.2023.3281726
Sen Bing;Khengdauliu Chawang;J.-C. Chiao
In this work, a planar microwave sensor based on a flexible polyimide substrate has been developed to distinguish if a skin lesion is malignant or benign. The sensor is a tuned loop resonator operating in the industrial, scientific, and medical (ISM) band at 2.465 GHz, providing a localized high-intensity electric field that penetrates into tissues with sufficient spatial and spectral resolutions. The loop resonator with a radius of 5.4 mm was tuned by a concentric metal pad to the desired resonant frequency with a sufficiently high quality factor of 98.7 and a reflection coefficient of $-$ 63.98 dB. The sensor is based on the detection of electromagnetic resonance change and sequential frequency shift that is susceptible to the dielectric property difference between cancerous and benign tissues. Basal Cell Carcinoma (BCC) and Seborrheic Keratosis (SK), the most commonly found malignant and benign skin lesions with close visual similarities, were selected to demonstrate the sensing concept. Tissue-mimicking materials were fabricated to have similar dielectric properties to those of healthy skin, SK, and BCC tissues in the literature. Simulations and measurements were conducted. Significant frequency shifts of 759 MHz and 415 MHz were observed between BCC and SK phantoms in simulations and measurements, respectively, when the size of the tumor phantom was a cuboid of 12 mm × 12 mm × 4 mm underneath and among healthy skin. Simulations were conducted for different cuboid side lengths from 2 to 16 mm while the thickness remained at 4 mm. Malignant lesions could be distinguished with a cuboid side length as small as 2 mm. Corresponding measurements for cuboid side lengths of 6, 8, 10, and 12 mm were conducted and matched the trend well with the simulation results. The promising results in simulations and measurements validate the sensing principle, showing great potential for skin cancer detection in a noninvasive, efficient, and lower-cost way.
在这项工作中，基于柔性聚酰亚胺衬底的平面微波传感器已经开发出来，以区分皮肤病变是恶性还是良性。该传感器是一个调谐环路谐振器，工作在2.465 GHz的工业、科学和医疗(ISM)频段，提供局部高强度电场，穿透组织，具有足够的空间和光谱分辨率。环形谐振器的半径为5.4 mm，通过同心金属衬垫调谐到所需的谐振频率，质量因子为98.7，反射系数为$-$63.98 dB。该传感器是基于检测易受癌组织和良性组织介电特性差异影响的电磁共振变化和顺序频移。基底细胞癌(BCC)和脂溢性角化病(SK)是最常见的恶性和良性皮肤病变，具有密切的视觉相似性，被选择来证明感知概念。在文献中，组织模拟材料被制造成具有与健康皮肤、SK和BCC组织相似的介电特性。进行了模拟和测量。在模拟和测量中，当肿瘤幻影在健康皮肤下为12 mm × 12 mm × 4 mm的长方体时，在BCC和SK幻影之间分别观察到759 MHz和415 MHz的显著频移。在厚度保持在4 mm的情况下，对2 ~ 16 mm的不同长方体边长进行了模拟。恶性病变可以通过长至2mm的长方体边长来区分。对长方体边长6、8、10和12 mm进行了相应的测量，结果与仿真结果吻合较好。仿真和测量结果验证了传感原理，显示出以无创、高效和低成本的方式进行皮肤癌检测的巨大潜力。
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