Rectenna circuits for RF energy harvesting in miniature DBS devices.

 Development of an optimum rectenna for radio frequency energy harvesting in miniature head-mountable deep brain stimulation (DBS) devices. The designed miniature rectenna can operate a DBS device without battery for murine preclinical research. The battery-less operation of the device eliminates battery related difficulties

Antenna Development in Brain-Implantable Biotelemetric Systems for Next-Generation of Human Healthcare

In the growing efforts of promoting patients’ life quality through health technology solutions, implantable wireless medical devices (IMDs) have been identified as one of the frontrunners. They are bringing compelling wireless solutions for medical diagnosis and treatment through bio-telemetric systems that deliver real-time transmission of in-body physiological data to an external monitoring/control unit. To set up this bidirectional wireless biomedical communication link for the long- term, the IMDs need small and efficient antennas. Designing antenna-enabled biomedical telemetry is a challenging aim, which must fulfill demanding issues and criteria including miniaturization, appropriate radiation performance, bandwidth enhancement, good impedance matching, and biocompatibility. Overcoming the size restriction mainly depends on the resonant frequency of the required applications. Defined frequency bands for biomedical telemetry systems contain the Medical Implant Communication Service (MICS) operating at the frequency band of 402– 405 MHz, Medical Device Radiocommunication Service (MedRadio) resonating at the frequency ranges of 401– 406 MHz, 413 – 419 MHz, 426 – 432 MHz, 438 – 444 MHz, and 451 – 457 MHz, Wireless Medical Telemetry Service (WMTS) operating at frequency specturms of 1395 to 1400 MHz and 1427 to 1432 MHz, and Industrial, Scientific, and Medical (ISM) bands of 433.1–434.8 MHz, 868–868.6 MHz, 902.8–928.0 MHz, and 2.4–2.48 GHz. On the other hand, a single band antenna may not fulfill all requirements of a bio-telemetry system in either MedRadio, WMTS, or ISM bands. As a result, analyzing dual/multi-band implantable antenna supporting wireless power, data transmission, and control signaling can meet the demand for multitasking biotelemetry systems. In addition, among different antenna structures, PIFA has been found a promising type in terms of size-performance balance in lossy human tissues. To overcome the above-mentioned challenges, this thesis, first, starts with a discussion of antenna radiation in a lossy medium, the requirements of implantable antenna development, and numerical modeling of the human head tissues. In the following discussion, we concentrate on approaching a new design for far-field small antennas integrated into brain-implantable biotelemetric systems that provide attractive features for versatile functions in modern medical applications. To this end, we introduce three different implantable antenna structures including a compact dual-band PIFA, a miniature triple-band PIFA and a small quad-band PIFA for brain care applications. The compelling performance of the proposed antennas is analyzed and discussed with simulation results and the triple-band PIFA is evaluated using simulation outcomes compared with the measurement results of the fabricated prototype. Finally, the first concept and platform of in-body and off-body units are proposed for wireless dopamine monitoring as a brain care application. In addition to the main focus of this thesis, in the second stage, we focus on introducing an equivalent circuit model to the electrical connector-line transition. We present a data fitting technique for two transmission lines characterization independent of the dielectric properties of the substrate materials at the ultra-high frequency band (UHF). This approach is a promising solution for the development of wearable and off-body antennas employing textile materials in biomedical telemetry systems. The approach method is assessed with measurement results of several fabricated transmission lines on different substrate materials

Self-folding 3D micro antennas for implantable medical devices

Tese de Doutoramento em Engenharia Biomédica.Recent advances in device miniaturization have been enabling smart and small implantable medical devices. These are often powered by bulky batteries whose dimensions represent one of the major bottlenecks on further device miniaturization. However, alternative powering methods, such as electromagnetic waves, do not rely on stored energy and are capable of providing high energy densities per unit of area, thus increasing the potential for device miniaturization. Hence, we envision an implanted medical device with an integrated miniaturized antenna, capable of receiving a radiofrequency signal from an exterior source, and converting it to a DC signal, thus enabling remote powering. This thesis addresses the analysis, design, fabrication and characterization of novel 3D micro antennas that can be integrated on 500 × 500 × 500 μm3 cubic devices, and used for wireless power transfer purposes. The analysis is built upon the theory of electrically small antennas in lossy media, and the antenna design takes into consideration miniaturization techniques which are compatible with the antenna fabrication process. For the antenna fabrication, a methodology that combines conventional planar photolithography techniques and self-folding was used. While photolithography allows the easy patterning of virtually every desired planar antenna configuration with reproducible feature precision, and the flexibility to easily and precisely change the antenna geometry and size, self-folding allows assembly of the fabricated planar patterns into a 3D structure in a highly parallel and scalable manner. After fabrication, we characterized the fabricated antennas by measuring their S-parameters and radiation patterns, demonstrating their efficacy at 2 GHz when immersed in dispersive media such as water. This step required the development and test of multiple characterization setups based on connectors, RF probes and transmission lines and the use of an anechoic chamber. Moreover, we successfully show that the antennas can wireless transfer energy to power an LED, highlighting a proof of concept for practical applications. Our findings suggest that self-folding micro antennas could provide a viable solution for powering tiny micro devices.Os recentes avanços das tecnologias de miniaturização têm permitido o desenvolvimento de dispositivos médicos implantáveis inteligentes e mais pequenos. Estes são muitas vezes alimentados por baterias volumosas cujas dimensões limitam o nível de miniaturização alcançável por um micro dispositivo. No entanto, existem formas alternativas de alimentar estes dispositivos que não dependem de energia armazenada, tais como ondas eletromagnéticas, que são capazes de providenciar uma elevada densidade de energia por unidade de área, aumentando assim o potencial de miniaturização dos dispositivos. Desta forma, visionamos um dispositivo médico implantado, com uma antena miniaturizada e integrada, capaz de receber um sinal de rádio frequência a partir de uma fonte externa, e convertê-lo num sinal DC, permitindo assim a alimentação remota do aparelho. Esta tese apresenta a análise, desenho, fabrico e caracterização de micro antenas 3D, passíveis de serem integradas em micro dispositivos cúbicos (500 × 500 × 500 μm3), e utilizadas para fins de transferência de energia sem fios. A análise assenta na teoria das antenas eletricamente pequenas em meios com perdas, e o design da antena considera técnicas de miniaturização de antenas. Para o fabrico da antena foi utilizada uma metodologia que combina técnicas de fotolitografia planar e auto-dodragem (self-folding). Enquanto a fotolitografia permite a padronização de virtualmente todos os tipos de configurações planares de forma precisa, reprodutível, e com a flexibilidade para se mudar rapidamente a geometria e o tamanho da antena, o self-folding permite a assemblagem dos painéis planares fabricados numa estrutura 3D. Depois do fabrico, as antenas foram caracterizadas medindo os seus parâmetros S e diagramas de radiação, demonstrando a sua eficácia a 2 GHz quando imersas num meio dispersivo, tal como água. Esta etapa exigiu o desenvolvimento e teste de várias setups de caracterização com base em conectores, sondas de RF e linhas de transmissão, e ainda o uso de uma câmara anecóica. Além disso, mostramos com sucesso que as micro antenas podem receber e transferir o energia para um LED acendendo-o, destacando assim esta prova de conceito para aplicações práticas. Os nossos resultados sugerem que estas micro antenas auto-dobráveis podem fornecer uma solução viável para alimentar micro dispositivos implantáveis muito pequenos.Fundação para a Ciência e a Tecnologia (FCT) bolsa SFRH/BD/63737/2009

Doctor of Philosophy

dissertationAntenna design and reduction of losses in antenna systems are critical for modern communications systems. Two categories of antennas suffer from limited power supply and difficult operating environments: implantable antennas and antennas for spacecraft applications. Minimizing and controlling losses in these two antenna types is critical for developing next-generation implantable devices, spacecraft, and satellites. Research suggests that future tattoo antennas will be made from low-conductivity ink utilizing the natural insulating property of the body's fat and lossy ground plane of muscle. This paper supports tattoo antenna work by: (1) demonstrating the insulating properties of fat and conductivity of muscle with various antenna systems, (2) showing the effect of biological materials on the current distribution of subdermal antennas, and (3) validating the use of lower-conductivity materials in subdermal antenna design including a novel gold nanoparticle material. Simulations and measurements are used to evaluate current distributions shared between solid, segmented, and meshed strip dipole antennas and surrounding body tissues. Fat insulates the antenna similar to a thin layer of plastic wrap. Muscle acts as a conductive ground plane. Dipole antennas with mesh or gap structures are more strongly coupled to body tissues than solid antennas. A minimum acceptable conductivity benchmark of 105 S/m is established for dipole antennas and Radio-Frequency Identification (RFID) antennas. This work also provides novel information on the design of low-cost, circularly polarized (CP), Ka-band (26 GHz), millimeter-wave, 50 Ω edge-fed, corners truncated patch antennas on RT/duroid 5880 (εr = 2.2, ½ oz. copper cladding). Microstrip feed width, axial ratio (AR) bandwidth, and best AR at 26 GHz are optimized by the use of 10 mil substrate. The effects of corner truncation are further investigated, showing that increasing corner truncation increases AR bandwidth, increases percent offset between best S11 and AR frequencies, and worsens the best AR. A truncation of 0.57 mm is a good compromise between these effects with AR bandwidth of 6.17 % (measured) and 1.37 % (simulated). Increasing ratio of substrate thickness to design frequency, t / λd, improves AR bandwidth. For t / λd below a certain threshold a corners truncated patch antenna will not produce CP. A new nearly-square, corners truncated patch antenna is measured and simulated as a method of increasing circular polarization bandwidth (CPBW)

소형동물의 뇌신경 자극을 위한 완전 이식형 신경자극기

학위논문(박사)--서울대학교 대학원 :공과대학 전기·정보공학부,2020. 2. 김성준.In this study, a fully implantable neural stimulator that is designed to stimulate the brain in the small animal is described. Electrical stimulation of the small animal is applicable to pre-clinical study, and behavior study for neuroscience research, etc. Especially, behavior study of the freely moving animal is useful to observe the modulation of sensory and motor functions by the stimulation. It involves conditioning animal's movement response through directional neural stimulation on the region of interest. The main technique that enables such applications is the development of an implantable neural stimulator. Implantable neural stimulator is used to modulate the behavior of the animal, while it ensures the free movement of the animals. Therefore, stable operation in vivo and device size are important issues in the design of implantable neural stimulators. Conventional neural stimulators for brain stimulation of small animal are comprised of electrodes implanted in the brain and a pulse generation circuit mounted on the back of the animal. The electrical stimulation generated from the circuit is conveyed to the target region by the electrodes wire-connected with the circuit. The devices are powered by a large battery, and controlled by a microcontroller unit. While it represents a simple approach, it is subject to various potential risks including short operation time, infection at the wound, mechanical failure of the device, and animals being hindered to move naturally, etc. A neural stimulator that is miniaturized, fully implantable, low-powered, and capable of wireless communication is required. In this dissertation, a fully implantable stimulator with remote controllability, compact size, and minimal power consumption is suggested for freely moving animal application. The stimulator consists of modular units of surface-type and depth-type arrays for accessing target brain area, package for accommodating the stimulating electronics all of which are assembled after independent fabrication and implantation using customized flat cables and connectors. The electronics in the package contains ZigBee telemetry for low-power wireless communication, inductive link for recharging lithium battery, and an ASIC that generates biphasic pulse for neural stimulation. A dual-mode power-saving scheme with a duty cycling was applied to minimize the power consumption. All modules were packaged using liquid crystal polymer (LCP) to avoid any chemical reaction after implantation. To evaluate the fabricated stimulator, wireless operation test was conducted. Signal-to-Noise Ratio (SNR) of the ZigBee telemetry were measured, and its communication range and data streaming capacity were tested. The amount of power delivered during the charging session depending on the coil distance was measured. After the evaluation of the device functionality, the stimulator was implanted into rats to train the animals to turn to the left (or right) following a directional cue applied to the barrel cortex. Functionality of the device was also demonstrated in a three-dimensional maze structure, by guiding the rats to navigate better in the maze. Finally, several aspects of the fabricated device were discussed further.본 연구에서는 소형 동물의 두뇌를 자극하기 위한 완전 이식형 신경자극기가 개발되었다. 소형 동물의 전기자극은 전임상 연구, 신경과학 연구를 위한 행동연구 등에 활용된다. 특히, 자유롭게 움직이는 동물을 대상으로 한 행동 연구는 자극에 의한 감각 및 운동 기능의 조절을 관찰하는 데 유용하게 활용된다. 행동 연구는 두뇌의 특정 관심 영역을 직접적으로 자극하여 동물의 행동반응을 조건화하는 방식으로 수행된다. 이러한 적용을 가능케 하는 핵심기술은 이식형 신경자극기의 개발이다. 이식형 신경자극기는 동물의 움직임을 방해하지 않으면서도 그 행동을 조절하기 위해 사용된다. 따라서 동물 내에서의 안정적인 동작과 장치의 크기가 이식형 신경자극기를 설계함에 있어 중요한 문제이다. 기존의 신경자극기는 두뇌에 이식되는 전극 부분과, 동물의 등 부분에 위치한 회로부분으로 구성된다. 회로에서 생산된 전기자극은 회로와 전선으로 연결된 전극을 통해 목표 지점으로 전달된다. 장치는 배터리에 의해 구동되며, 내장된 마이크로 컨트롤러에 의해 제어된다. 이는 쉽고 간단한 접근방식이지만, 짧은 동작시간, 이식부위의 감염이나 장치의 기계적 결함, 그리고 동물의 자연스러운 움직임 방해 등 여러 문제점을 야기할 수 있다. 이러한 문제의 개선을 위해 무선통신이 가능하고, 저전력, 소형화된 완전 이식형 신경자극기의 설계가 필요하다. 본 연구에서는 자유롭게 움직이는 동물에 적용하기 위하여 원격 제어가 가능하며, 크기가 작고, 소모전력이 최소화된 완전이식형 자극기를 제시한다. 설계된 신경자극기는 목표로 하는 두뇌 영역에 접근할 수 있는 표면형 전극과 탐침형 전극, 그리고 자극 펄스 생성 회로를 포함하는 패키지 등의 모듈들로 구성되며, 각각의 모듈은 독립적으로 제작되어 동물에 이식된 뒤 케이블과 커넥터로 연결된다. 패키지 내부의 회로는 저전력 무선통신을 위한 지그비 트랜시버, 리튬 배터리의 재충전을 위한 인덕티브 링크, 그리고 신경자극을 위한 이상성 자극파형을 생성하는 ASIC으로 구성된다. 전력 절감을 위해 두 개의 모드를 통해 사용률을 조절하는 방식이 장치에 적용된다. 모든 모듈들은 이식 후의 생물학적, 화학적 안정성을 위해 액정 폴리머로 패키징되었다. 제작된 신경자극기를 평가하기 위해 무선 동작 테스트가 수행되었다. 지그비 통신의 신호 대 잡음비가 측정되었으며, 해당 통신의 동작거리 및 데이터 스트리밍 성능이 검사되었고, 장치의 충전이 수행될 때 코일간의 거리에 따라 전송되는 전력의 크기가 측정되었다. 장치의 평가 이후, 신경자극기는 쥐에 이식되었으며, 해당 동물은 이식된 장치를 이용해 방향 신호에 따라 좌우로 이동하도록 훈련되었다. 또한, 3차원 미로 구조에서 쥐의 이동방향을 유도하는 실험을 통하여 장치의 기능성을 추가적으로 검증하였다. 마지막으로, 제작된 장치의 특징이 여러 측면에서 심층적으로 논의되었다.Chapter 1 : Introduction 1 1.1. Neural Interface 2 1.1.1. Concept 2 1.1.2. Major Approaches 3 1.2. Neural Stimulator for Animal Brain Stimulation 5 1.2.1. Concept 5 1.2.2. Neural Stimulator for Freely Moving Small Animal 7 1.3. Suggested Approaches 8 1.3.1. Wireless Communication 8 1.3.2. Power Management 9 1.3.2.1. Wireless Power Transmission 10 1.3.2.2. Energy Harvesting 11 1.3.3. Full implantation 14 1.3.3.1. Polymer Packaging 14 1.3.3.2. Modular Configuration 16 1.4. Objectives of This Dissertation 16 Chapter 2 : Methods 18 2.1. Overview 19 2.1.1. Circuit Description 20 2.1.1.1. Pulse Generator ASIC 21 2.1.1.2. ZigBee Transceiver 23 2.1.1.3. Inductive Link 24 2.1.1.4. Energy Harvester 25 2.1.1.5. Surrounding Circuitries 26 2.1.2. Software Description 27 2.2. Antenna Design 29 2.2.1. RF Antenna 30 2.2.1.1. Design of Monopole Antenna 31 2.2.1.2. FEM Simulation 31 2.2.2. Inductive Link 36 2.2.2.1. Design of Coil Antenna 36 2.2.2.2. FEM Simulation 38 2.3. Device Fabrication 41 2.3.1. Circuit Assembly 41 2.3.2. Packaging 42 2.3.3. Electrode, Feedthrough, Cable, and Connector 43 2.4. Evaluations 45 2.4.1. Wireless Operation Test 46 2.4.1.1. Signal-to-Noise Ratio (SNR) Measurement 46 2.4.1.2. Communication Range Test 47 2.4.1.3. Device Operation Monitoring Test 48 2.4.2. Wireless Power Transmission 49 2.4.3. Electrochemical Measurements In Vitro 50 2.4.4. Animal Testing In Vivo 52 Chapter 3 : Results 57 3.1. Fabricated System 58 3.2. Wireless Operation Test 59 3.2.1. Signal-to-Noise Ratio Measurement 59 3.2.2. Communication Range Test 61 3.2.3. Device Operation Monitoring Test 62 3.3. Wireless Power Transmission 64 3.4. Electrochemical Measurements In Vitro 65 3.5. Animal Testing In Vivo 67 Chapter 4 : Discussion 73 4.1. Comparison with Conventional Devices 74 4.2. Safety of Device Operation 76 4.2.1. Safe Electrical Stimulation 76 4.2.2. Safe Wireless Power Transmission 80 4.3. Potential Applications 84 4.4. Opportunities for Further Improvements 86 4.4.1. Weight and Size 86 4.4.2. Long-Term Reliability 93 Chapter 5 : Conclusion 96 Reference 98 Appendix - Liquid Crystal Polymer (LCP) -Based Spinal Cord Stimulator 107 국문 초록 138 감사의 글 140Docto

Microwave antennas for biomedical application

Medical diagnosis is one of the key steps to determine the problem of the human body. The current diagnostic tools are expensive, bulky and long exposure to some of these diagnostic tools can be injurious to the human body. Hence, researchers are now exploring through different possibilities to replace current diagnostic tools. Microwave regime is one of the potential candidate to replace current diagnostic system providing with a chip, portable system suitable for the human body. One of the fundamental tool for a microwave diagnostic system is microwave antenna. The current findings on designing microwave antennas for biomedical diagnosis lacks due to low microwave power penetration inside the human body, high specific absorption rate (SAR), low directivity and compactness. This thesis aims on improving the microwave penetration inside the human body and develop antennas that can perform efficiently for biomedical diagnosis application. A multi-layer reflection model is investigated for evaluation of the combined material characteristics of different lossy human tissues, along with the enhanced antenna designs, suitable for biomedical application, operating on-body and as an implant, have been presented within this thesis. The rationale behind this work relates to the early detection of cancerous tissues, internal injuries and other characteristic changes inside the human body with the primary goals being to improve microwave power penetration inside the human body and to provide low SAR and compact microwave antenna system for biomedical diagnosis. The penetration of microwave power inside a human head model is improved by employing calculated permittivity inside a rectangular waveguide used as the microwave transmission source. Firstly, a multi-layer reflection model is created from various human tissue material. The wave impedance of the multi-layer is then extracted from the overall reflection coefficient found at the edge of the multi-layer tissue model. Furthermore, a rectangular waveguide is constructed and an L-probe rectangular waveguide feeding technique is presented. The measured results validate the approach with an increment in power penetration inside the human head 1.33 dB at 2.45 GHz.  Antennas are characterized in-front of homogeneous and a frequency-dependent inhomogeneous human head and shown that inhomogeneous phantom provides with real-life scenario for the measuring antenna whereas the homogeneous phantom only resembles the scenario. The effect of superstrate at the boresight of an on-head matched antenna for biomedical applications is analysed and shown that superstrate layer at the boresight direction of the antenna provides with ~8 dB increased directivity towards the human head with 0.0731 W/kg reduction of SAR compared to the antenna without the superstrate. The design of a 3-D on-body antenna and a coplanar waveguide (CPW) fade antenna matched with an inhomogeneous human head provides the second investigation area. Specific focus has been given to make the designs compact, increase the front to back ratio (FBR) of the radiation pattern and decrease the SAR of the antenna. The 3-D antenna is realized combining a folded inverted F-like structure and a slot-loaded ground plane and backed by a rectangular cavity to minimize side and back lobe radiation. An FBR of 17 dB with SAR less than 0.0147 W/kg is achieved throughout the operating frequency ranging from 1 - 1.7 GHz by the designed antenna while acquiring a compact dimension of 0.23 × 0.23 × 0.04 λ in size with respect to the lowest operating frequency.  An inhomogeneous human head phantom is constructed and used to analyze the antennas performance in real-life scenario. Moreover, the choice of operating frequency for on-head antennas and effect of a superstrate on on-head matched antennas is investigated. An FBR of 20 dB with SAR less than 0.037 W/kg is achieved throughout the operating frequency ranging from 0.788 - 2.5 GHz by the designed antenna while acquiring a compact dimension of 0.1 × 0.1 × 0.008 λ in size with respect to the lowest operating frequency. Finally, the design of an implantable coil antenna is investigated for wireless power transmission inside the human body. The biocompatibility of the building material is analyzed. Polydimethylsiloxane (PDMS) and gold (Au) is utilized as the biocompatible building material to realize the designed implantable antenna. Furthermore, the antenna is characterized in a "complete medium" composed of fetal bovine serum (FBS), penicillin-streptomycin and dulbecco's modified eagle's medium (DMEM) which is used as the cell culture media to resemble designed antennas operation environment. The antenna is impedance matched at 5 MHz frequency with a maximum received voltage of 35 mV is recorded by utilizing the designed implantable antenna

Implanted Antennas for Biomedical Applications

Body-Centric Wireless Communication (BCWC) is a central topic in the development of healthcare and biomedical technologies. Increasing healthcare quality, in addition to the continuous miniaturisation of sensors and the advancement in wearable electronics, embedded software, digital signal processing and biomedical technologies, has led to a new era of biomedical devices and increases possibility of continuous monitoring, diagnostic and/or treatment of many diseases. However, the major difference between BCWC, particularly implantable devices, and conventional wireless systems is the radio channel over which the communication takes place. The human body is a hostile environment from a radio propagation perspective. This environment is a highly lossy and has a high effect on the antenna elements, the radio channel parameters and, hence a dramatic drop in the implanted antenna performance. This thesis focuses on how to improve the gain of implanted antennas. In order to improve the gain and performance of implanted antennas, this thesis uses a combination of experimental and electromagnetic numerical investigations. Extensive simulation and experimental investigations are carried out to study the effects of various external elements on the performance improvement of implanted antennas. The thesis also shows the design, characterisation, simulation and measurements of four different antennas to work at ISM band and seventeen different scenarios for body wireless communication. A 3- layer (skin, fat and muscle) and a liquid homogenise phantom were used for human body modelling in both simulation and measurements. The results shows that a length of printed line and a grid can be used on top of the human skin in order enhance the performance of the implanted antennas. Moreover, a ring and a hemispherical lens can be used externally in order to enhance the performance of the implanted antenna. This approach yields a significant improvement in the antenna gain and reduces the specific absorption rate (SAR) in most cases and the obtained gain varies between 2 dB and 8 dB

Modelling and characterisation of antennas and propagation for body-centric wireless communication

PhDBody-Centric Wireless Communication (BCWC) is a central point in the development of fourth generation mobile communications. The continuous miniaturisation of sensors, in addition to the advancement in wearable electronics, embedded software, digital signal processing and biomedical technologies, have led to a new concept of usercentric networks, where devices can be carried in the user’s pockets, attached to the user’s body or even implanted. Body-centric wireless networks take their place within the personal area networks, body area networks and body sensor networks which are all emerging technologies that have a broad range of applications such as healthcare and personal entertainment. The major difference between BCWC and conventional wireless systems is the radio channel over which the communication takes place. The human body is a hostile environment from radio propagation perspective and it is therefore important to understand and characterise the effect of the human body on the antenna elements, the radio channel parameters and hence the system performance. This is presented and highlighted in the thesis through a combination of experimental and electromagnetic numerical investigations, with a particular emphasis to the numerical analysis based on the finite-difference time-domain technique. The presented research work encapsulates the characteristics of the narrowband (2.4 GHz) and ultra wide-band (3-10 GHz) on-body radio channels with respect to different digital phantoms, body postures, and antenna types hence highlighting the effect of subject-specific modelling, static and dynamic environments and antenna performance on the overall body-centric network. The investigations covered extend further to include in-body communications where the radio channel for telemetry with medical implants is also analysed by considering the effect of different digital phantoms on the radio channel characteristics. The study supports the significance of developing powerful and reliable numerical modelling to be used in conjunction with measurement campaigns for a comprehensive understanding of the radio channel in body-centric wireless communication. It also emphasises the importance of considering subject-specific electromagnetic modelling to provide a reliable prediction of the network performance