Modulation Techniques for Biomedical Implanted Devices and Their Challenges

Implanted medical devices are very important electronic devices because of their usefulness in monitoring and diagnosis, safety and comfort for patients. Since 1950s, remarkable efforts have been undertaken for the development of bio-medical implanted and wireless telemetry bio-devices. Issues such as design of suitable modulation methods, use of power and monitoring devices, transfer energy from external to internal parts with high efficiency and high data rates and low power consumption all play an important role in the development of implantable devices. This paper provides a comprehensive survey on various modulation and demodulation techniques such as amplitude shift keying (ASK), frequency shift keying (FSK) and phase shift keying (PSK) of the existing wireless implanted devices. The details of specifications, including carrier frequency, CMOS size, data rate, power consumption and supply, chip area and application of the various modulation schemes of the implanted devices are investigated and summarized in the tables along with the corresponding key references. Current challenges and problems of the typical modulation applications of these technologies are illustrated with a brief suggestions and discussion for the progress of implanted device research in the future. It is observed that the prime requisites for the good quality of the implanted devices and their reliability are the energy transformation, data rate, CMOS size, power consumption and operation frequency. This review will hopefully lead to increasing efforts towards the development of low powered, high efficient, high data rate and reliable implanted devices

Advances in Microelectronics for Implantable Medical Devices

Implantable medical devices provide therapy to treat numerous health conditions as well as monitoring and diagnosis. Over the years, the development of these devices has seen remarkable progress thanks to tremendous advances in microelectronics, electrode technology, packaging and signal processing techniques. Many of today’s implantable devices use wireless technology to supply power and provide communication. There are many challenges when creating an implantable device. Issues such as reliable and fast bidirectional data communication, efficient power delivery to the implantable circuits, low noise and low power for the recording part of the system, and delivery of safe stimulation to avoid tissue and electrode damage are some of the challenges faced by the microelectronics circuit designer. This paper provides a review of advances in microelectronics over the last decade or so for implantable medical devices and systems. The focus is on neural recording and stimulation circuits suitable for fabrication in modern silicon process technologies and biotelemetry methods for power and data transfer, with particular emphasis on methods employing radio frequency inductive coupling. The paper concludes by highlighting some of the issues that will drive future research in the field

Wireless body sensor networks for health-monitoring applications

This is an author-created, un-copyedited version of an article accepted for publication in Physiological Measurement. The publisher is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at http://dx.doi.org/10.1088/0967-3334/29/11/R01

Remote Powering and Data Communication Over a Single Inductive Link for Implantable Medical Devices

RÉSUMÉ Les implants médicaux électroniques (Implantable Medical Devices - IMDs) sont notamment utilisés pour restaurer ou améliorer des fonctions perdues de certains organes. Ils sont capables de traiter des complications qui ne peuvent pas être guéries avec des médicaments ou par la chirurgie. Offrant des propriétés et des améliorations curatives sans précédent, les IMDs sont de plus en plus demandés par les médecins et les patients. En 2017, le marché mondial des IMD était évalué à 15,21 milliards de dollars. D’ici 2025, il devrait atteindre 30,42 mil-liards de dollars, soutenu par un taux de croissance annuel de 9,24% selon le nouveau rapport publié par Fior Markets. Cette expansion entraîne une augmentation des exigences pour as-surer des performances supérieures, des fonctionnalités supplémentaires et une durée de vie plus longue. Ces exigences ne peuvent être satisfaites qu’avec des techniques d’alimentation avancées, un débit de données élevé et une électronique miniaturisée robuste. Construire des systèmes capables de fournir toutes ces caractéristiques est l’objectif principal d’un grand nombre de chercheurs. Parmi plusieurs technologies sans fil, le lien inductif, qui consiste en une paire de bobines à couplage magnétique, est la technique sans fil la plus largement utilisée pour le transfert de puissance et de données. Cela est dû à sa simplicité, sa sécurité et sa capacité à transmettre à la fois de la puissance et des données de façon bidirectionnelle. Cependant, il existe encore un certain nombre de défis concernant la mise en œuvre d’un tel système de transfert d’énergie et de données sans fil (Wireless Power and Data Transfer - WPDT system). Un défi majeur est que les exigences pour une efficacité de transfert d’énergie élevée et pour une communication à haut débit sont contradictoires. En fait, la bande passante doit être élargie pour des débits de données élevés, mais réduite pour une transmission efficace de l’énergie. Un autre grand défi consiste à réaliser un démodulateur fonctionnant à haute vitesse avec une mise en œuvre simple et une consommation d’énergie ultra-faible. Dans ce projet, nous proposons et expérimentons un nouveau système WPDT dédié aux IMD permettant une communication à haute vitesse et une alimentation efficace tout en maintenant une faible consommation d’énergie, une petite surface de silicium et une mise en œuvre simple du récepteur. Le système proposé est basé sur un nouveau schéma de modulation appelé "Carrier Width Modulation (CWM)", ainsi que sur des circuits de modulation et de démodulation inédits. La modulation consiste en un coupe-circuit synchronisé du réservoir LC primaire pendant un ou deux cycles en fonction des données transmises.----------ABSTRACT Implantable Medical Devices (IMDs) are electronic implants notably used to restore or en-hance lost organ functions. They may treat complications that cannot be cured with medica-tion or through surgery. O˙ering unprecedented healing properties and enhancements, IMDs are increasingly requested by physicians and patients. In 2017, the worldwide IMD market was valued at USD 15,21 Billion. By 2025, it is expected to attain USD 30.42 Billion sus-tained by a compound annual growth rate of 9.24% according to a recent report published by Fior Markets. This expansion is bringing-up more demand for higher performance, additional features, and longer device lifespan and autonomy. These requirements can only be achieved with advanced power sources, high-data rates, and robust miniaturized electronics. Building systems able to provide all these characteristics is the main goal of many researchers. Among several wireless technologies, the inductive link, which consists of a magnetically-coupled pair of coils, is the most widely used wireless technique for both power and data transfer. This is due to its simplicity, safety, and ability to provide simultaneously both power and bidirectional data transfer to the implant. However there are still a number of challenges regarding the implementation of such Wireless Power and Data Transfer (WPDT) systems. One main challenge is that the requirements for high Power Transfer Eÿciency (PTE) and for high-data rate communication are contra-dictory. In fact, the bandwidth needs to be widened for high data rates, but narrowed for eÿcient power delivery. Another big challenge is to implement a high-speed demodulator with simple implementation and ultra-low power consumption. In this project, we propose and experiment a new WPDT system dedicated to IMDs allow-ing high-speed communication and eÿcient power delivery, while maintaining a low power consumption, small silicon area, and simple implementation of the receiver. The proposed system is based on a new Carrier Width Modulation (CWM) scheme, as well as novel modu-lation and demodulation circuits. The modulation consists of a synchronized opening of the primary LC tank for one or two cycles according to the transmitted data. Unlike conventional modulation techniques, the data rate of the proposed CWM modulation is not limited by the quality factors of the primary and secondary coils. On the other hand, the proposed CWM demodulator allows higher-speed demodulation and simple implementation, unlike conven-tional demodulators for a similar modulation scheme. It also o˙ers a wide range of data rates under any selected frequency from 10 to 31 MHz

A TRANSCEIVER DESIGN FOR IMPLANTABLE MEDICAL DEVICES

Master'sMASTER OF ENGINEERIN

Design of Wireless Power Transfer and Data Telemetry System for Biomedical Applications

With the advancement of biomedical instrumentation technologies sensor based remote healthcare monitoring system is gaining more attention day by day. In this system wearable and implantable sensors are placed outside or inside of the human body. Certain sensors are needed to be placed inside the human body to acquire the information on the vital physiological phenomena such as glucose, lactate, pH, oxygen, etc. These implantable sensors have associated circuits for sensor signal processing and data transmission. Powering the circuit is always a crucial design issue. Batteries cannot be used in implantable sensors which can come in contact with the blood resulting in serious health risks. An alternate approach is to supply power wirelessly for tether-less and battery- less operation of the circuits.Inductive power transfer is the most common method of wireless power transfer to the implantable sensors. For good inductive coupling, the inductors should have high inductance and high quality factor. But the physical dimensions of the implanted inductors cannot be large due to a number of biomedical constraints. Therefore, there is a need for small sized and high inductance, high quality factor inductors for implantable sensor applications. In this work, design of a multi-spiral solenoidal printed circuit board (PCB) inductor for biomedical application is presented. The targeted frequency for power transfer is 13.56 MHz which is within the license-free industrial, scientific and medical (ISM) band. A figure of merit based optimization technique has been utilized to optimize the PCB inductors. Similar principal is applied to design on-chip inductor which could be a potential solution for further miniaturization of the implantable system. For layered human tissue the optimum frequency of power transfer is 1 GHz for smaller coil size. For this reason, design and optimization of multi-spiral solenoidal integrated inductors for 1 GHz frequency is proposed. Finally, it is demonstrated that the proposed inductors exhibit a better overall performance in comparison with the conventional inductors for biomedical applications