In situ characterization of two wireless transmission schemes for ingestible capsules

We report the experimental in situ characterization of 30-40 MHz and 868 MHz wireless transmission schemes for ingestible capsules, in porcine carcasses. This includes a detailed study of the performance of a magnetically coupled near-field very high-frequency (VHF) transmission scheme that requires only one eighth of the volume and one quarter of the power consumption of existing 868-MHz solutions. Our in situ measurements tested the performance of four different capsules specially constructed for this study (two variants of each transmission scheme), in two scenarios. One mimicked the performance of a body-worn receiving coil, while the other allowed the characterization of the direction-dependent signal attenuation due to losses in the surrounding tissue. We found that the magnetically coupled near-field VHF telemetry scheme presents an attractive option for future, miniturized ingestible capsules for medical applications

Design of wireless swallowable capsule with minimum power consumption and high resolution images

Medical technology has undergone major breakthroughs in recent years, especially in the area of the examination tools for diagnostic purposes. The traditional examination method for the diagnosis of gastrointestinal diseases is gastroscopy with the use of an endoscope. Wireless camera pill has created a new perspective for engineers and physicians. After years of great innovation, commercial swallowable pills have been produced and applied in clinical practice. These pills can cover the examination of the gastrointestinal system and provide to the physicians not only a lot more useful data that is not available from the traditional methods, but also elimination of the use of the painful endoscopy procedure. In this paper, a new design of the wireless swallowable pills has been proposed. It takes advantage of the benefits of every sub-system, like camera lenses, image compressor and RF sub-system. In this way our system can provide enough and accurate data to the physicians

Magnetic loop antenna for wireless capsule endoscopy inside the human body operating at 315 MHz: Near field behavior

In ingestible systems, the antenna suffers from deterioration of performances due to surrounding dissipative tissues. A small circular magnetic loop antenna, whose diameter is equal to 1 cm and thickness is equal to 0.5 mm operating at the frequency of 315 MHz in the ISM band, is proposed to limit this degradation. The electric properties of the human body, having a high dielectric constant and low impedance, are considered to design and simulate the loop antenna. We found that the magnetic field is less attenuated than the electric field in the human body that improves the signal level received by near field magnetic coupling

Material Processing for Edible Electronics

abstract: A new type of electronics was envisioned, namely edible electronics. Edible electronics are made by Food and Drug Administration (FDA) certified edible materials which can be eaten and digested by human body. Different from implantable electronics, test or treatment using edible electronics doesn’t require operations and perioperative complications. This dissertation bridges the food industry, material sciences, device fabrication, and biomedical engineering by demonstrating edible supercapacitors and electronic components and devices such as pH sensor. Edible supercapacitors were fabricated using food materials from grocery store. 5 of them were connected in series to power a snake camera. Tests result showed that the current generated by supercapacitor have the ability to kill bacteria. Next more food, processed food and non-toxic level electronic materials were investigated. A “preferred food kit” was created for component fabrication based on the investigation. Some edible electronic components, such as wires, resistor, inductor, etc., were developed and characterized utilizing the preferred food kit. These components make it possible to fabricate edible electronic/device in the future work. Some edible electronic components were integrated into an edible electronic system/device. Then edible pH sensor was introduced and fabricated. This edible pH sensor can be swallowed and test pH of gastric fluid. PH can be read in a phone within seconds after the pH sensor was swallowed. As a side project, an edible double network gel electrolyte was synthesized for the edible supercapacitor.Dissertation/ThesisDoctoral Dissertation Chemical Engineering 201

Conception d'antennes de communication à travers le corps humain pour le suivi thérapeutique

Avec le développement rapide des technologies sans fil modernes et la miniaturisation des antennes et des systèmes électriques, l'emploi des antennes à l'intérieur du corps humain pour le suivi thérapeutique est devenu possible. Des batteries permettent d'alimenter ces antennes ; la réduction de la consommation de puissance implique l'augmentation de la durée de vie de circuits ingérables. Le corps humain, qui a une conductivité non nulle, n'est pas un milieu idéal pour la transmission des ondes RF à cause de l'atténuation liée aux propriétés diélectriques des tissus biologiques. Cependant, les tissus humains ne perturbent pas le champ magnétique car celui-ci dépend de la perméabilité du milieu qui est égale à un dans le corps humain. Bien que la puissance du champ magnétique décroisse avec l'exposant six de la distance, la technique utilisant les communications par induction magnétique en champ proche a été adoptée dans cette étude pour concevoir une liaison sans fil à faible portée à travers le corps humain. Durant ces travaux de thèse, après une caractérisation détaillée de la bobine d'émission située à l'intérieur du corps humain et de la bobine de réception localisée à sa surface, nous avons mis en place un bilan de liaison pour contribuer à l'amélioration du transfert de puissance dans ce milieu dissipatif. Un modèle analytique, déterminant les facteurs qui peuvent affecter le bilan de liaison par induction magnétique, a été vérifié à travers les simulations et les mesures. La variation de la position et de l'orientation de l'antenne ingérable ont été prises en compte pour évaluer la réponse de couplage entre la bobine émettrice et la bobine réceptrice. Les résultats obtenus constituent un pas en avant vers de futures recherches sur la conception de antennes dans les milieux dissipatifs et en particulier le corps humainWith the rapid growth of wireless technology and the miniaturization of modern antennas and electrical systems, the use of antennas inside the human body for therapeutic monitoring became possible. Batteries are used to supply these antennas; reducing the power consumption allows to increase the lifetime of ingestible systems. The human body, which has non-zero conductivity, is not an ideal environment for the transmission of RF waves because of the attenuation due to the dielectric properties of biological tissues. However, the human tissues do not disrupt the magnetic field as it depends on the permeability of the medium which is equal to one in the human body. Although the magnetic field power decreases with the distance exponent six, the technique using near-field magnetic induction communications was adopted in this study to design a short range wireless link through the human body. In this thesis, after a detailed characterization of the transmitting coil antenna located inside the human body and the receiving coil placed on its surface, we have implemented a link budget to contribute to the improvement of power transfer in the dissipative medium. An analytical model, identifying factors that can affect the link budget by magnetic induction, has been verified through simulations and measurements. The variation of the position and the orientation of the ingestible antenna were taken into account to evaluate the coupling response between the transmitting coil and the receiving coil. The results are a step toward future research on the design of antennas in dissipative media, in particular the human bodyPARIS-EST-Université (770839901) / SudocSudocFranceF

의료용 인체 삽입물을 위한 무선 저전력 송수신기에 관한 연구

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2016. 2. 남상욱.This thesis presents the wireless transceiver for medical implant application. The high propagation loss in human body which has high relative permittivity and conductive makes the implantable device be required for high sensitivity. Moreover, the device should have low power consumption to use for wireless implant medical application due to a restricted battery life. Also, this problem should be solved for on-body device considering integration with mobile device in the future. Simultaneously, the specific medical application such as epiretinal prosthesis, multi-channel electroencephalogram sensor demand high-data rate. Therefore, it is a main challenge that enhancing the devices power consumption and data-rate for implantable medical application. In order to enhance the performance of the device, several techniques are proposed in implantable human body transceivers. Firstly, the propagation loss in human-body is calculated for determine the frequency for medical implant application. The frequency bands allocated by FCC or MICS are too narrow and high lossy bands in human-body. For this reason, the optimum frequency for Implantable medical device is found by using Frisss formula and the link budget is calculated for capsule endoscopy system. The optimum frequency is verified through image recovery experiment in liquid human phantom and pig by using designed capsule endoscopy system. Secondly, the Super-Regenerative Receiver (SRR) with Digital Self-Quenching Loop (DSQL) is proposed for low power consumption. The proposed DSQL replaces the envelope detector used in a conventional SRR and minimizes power consumption by generating a self-quench signal digitally for a super-regenerative oscillator. The measurement results are given to show the performance of the proposed receiver. Thirdly, the RF Current Reused and Current Combining (CRCC) Power Amplifier (PA) is proposed for low power and high-speed transmitter. Normally, the PA having low output power has a feasibility issue that an optimum impedance of PA is too high to match with antenna impedance. For this reason, obtaining the maximum efficiency of PA is difficult for conventional structure. Moreover, conventional PAs output bandwidth is to be narrow due to high impedance transform ratio between PAs output and antennas input impedances. The CRCC structure solves this issue by decreasing the impedance transform ratio. The transmitter with CRCC PA is designed and verified through the measurement.Chapter 1. Introduction 1 1.1. WBAN (Wireless Body Area Network) 1 1.2. Challenges in Designing Transceiver for Medical Implant Application 7 Chapter 2. Propagation Loss in Human Body 10 2.1. Introduction 10 2.2. Far field approximation in human-body 13 2.3. Calculation of propagation loss in human-body 15 2.3.1. Frisss formula 15 2.3.2. Efficiency of transmitting antenna in human-body 17 2.4. Calculation of propagation loss in human-body and conclusion 19 Chapter 3. A Design of Transceiver for Capsule Endoscopy Application 21 3.1. Introduction 21 3.2. System Link Budget Calculation 24 3.3. Implementation 26 3.3.1. Transmitter with class B amplifier 26 3.3.2. Super-heterodyne receiver with AGC 28 3.3.3. Measurement results 30 3.4. Image recovery experiment 35 3.4.1. Integration of capsule endoscopy 35 3.4.2. Image recovery in the liquid human phantom 38 3.4.3. Image recovery in a pigs stomach and large intestine 40 3.5. Conclusion 41 Chapter 4. Super-Regenerative Receiver with Digitally Self-Quenching Loop 42 4.1. Introduction 42 4.1.1. Selection of receivers architecture for implantable medical device 44 4.1.2. Previous study of super-regenerative receiver 50 4.2. Main idea of proposed super-regenerative receiver 51 4.3. Description of proposed receiver 53 4.3.1. Digital self-quenching loop 55 4.3.2. Low noise amplifier and super-regenerative oscillator 57 4.3.3. Active RC filter for low power consumption 59 4.4. Experimental results 63 4.5. Summary and conclusion 69 Chapter 5. A Transmitter with Current-Reused and Current-Combining PA 71 5.1. Introduction 71 5.1.1. Previous study of OOK transmitter 72 5.2. Main idea of proposed transmitter 73 5.3. Description of proposed transmitter 79 5.3.1. Current-combining and current-reused PA 79 5.3.2. Ring oscillator with driving buffer 83 5.4. Experimental Results 85 5.5. Summary and conclusion 93 Chapter 6. Conclusion 95 Chapter 7. Appendix 97 7.1. Output spectrum of OOK signal 97 7.2. Theoretical BER of OOK comunication 99 Bibliography 101 초 록 109Docto

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

Development of electronics for microultrasound capsule endoscopy

Development of intracorporeal devices has surged in the last decade due to advancements in the semiconductor industry, energy storage and low-power sensing systems. This work aims to present a thorough systematic overview and exploration of the microultrasound (µUS) capsule endoscopy (CE) field as the development of electronic components will be key to a successful applicable µUSCE device. The research focused on investigating and designing high-voltage (HV, < 36 V) generating and driving circuits as well as a low-noise amplifier (LNA) for battery-powered and volume-limited systems. In implantable applications, HV generation with maximum efficiency is required to improve the operational lifetime whilst reducing the cost of the device. A fully integrated hybrid (H) charge pump (CP) comprising a serial-parallel (SP) stage was designed and manufactured for > 20 V and 0 - 100 µA output capabilities. The results were compared to a Dickson (DKCP) occupying the same chip area; further improvements in the SPCP topology were explored and a new switching scheme for SPCPs was introduced. A second regulated CP version was excogitated and manufactured to use with an integrated µUS pulse generator. The CP was manufactured and tested at different output currents and capacitive loads; its operation with an US pulser was evaluated and a novel self-oscillating CP mechanism to eliminate the need of an auxiliary clock generator with a minimum area overhead was devised. A single-output universal US pulser was designed, manufactured and tested with 1.5 MHz, 3 MHz, and 28 MHz arrays to achieve a means of fully-integrated, low-power transducer driving. The circuit was evaluated for power consumption and pulse generation capabilities with different loads. Pulse-echo measurements were carried out and compared with those from a commercial US research system to characterise and understand the quality of the generated pulse. A second pulser version for a 28 MHz array was derived to allow control of individual elements. The work involved its optimisation methodology and design of a novel HV feedback-based level-shifter. A low-noise amplifier (LNA) was designed for a wide bandwidth µUS array with a centre frequency of 28 MHz. The LNA was based on an energy-efficient inverter architecture. The circuit encompassed a full power-down functionality and was investigated for a self-biased operation to achieve lower chip area. The explored concepts enable realisation of low power and high performance LNAs for µUS frequencies

New Techniques in Gastrointestinal Endoscopy

As result of progress, endoscopy has became more complex, using more sophisticated devices and has claimed a special form. In this moment, the gastroenterologist performing endoscopy has to be an expert in macroscopic view of the lesions in the gut, with good skills for using standard endoscopes, with good experience in ultrasound (for performing endoscopic ultrasound), with pathology experience for confocal examination. It is compulsory to get experience and to have patience and attention for the follow-up of thousands of images transmitted during capsule endoscopy or to have knowledge in physics necessary for autofluorescence imaging endoscopy. Therefore, the idea of an endoscopist has changed. Examinations mentioned need a special formation, a superior level of instruction, accessible to those who have already gained enough experience in basic diagnostic endoscopy. This is the reason for what these new issues of endoscopy are presented in this book of New techniques in Gastrointestinal Endoscopy