Introducing NFC for in-body and on-body medical sensors

Abstract

In the last few decades, the number of people suffering from chronic diseases that require continuous treatment and monitoring has been on the rise. To achieve a more cost-efficient health care system, and to offer better treatment for patients, monitoring of the physiological parameters could be carried out by the patients themselves using mobile health services, known in short as "mhealth". In this thesis, we focus on miniaturized battery-less implants and on-body sensors that use the near field communication (NFC) standard. This standard is now widely available on smartphones/ watches and is able to transfer energy and data to specific tags. Using this combination, the readings of the physiological parameters will be available on the phone and can thus be transferred to a health station for further processing. The main goal of this work is to provide a toolset for designing, implementing and testing complete systems for implantable sensory NFC tags spanning aspects from the sensory implant to portable devices (smart-phone/watch) and health-stations servers. This will provide a huge step forward towards continuous monitoring of physiological parameters such as glucose level, among others. Two different ASICs have been developed in 90nm CMOS to demonstrate how to connect different types of sensors to a unique type 1 tag in a standardized fashion, as well as a mobile application to control, power up and communicate with the sensory tag and, finally, an algorithm to exchange the data between the smart-phone and a server. We have demonstrated that multiple sensors monitoring different physiological parameters can be connected simultaneously to the same tag and provide continuous readings to a smart-phone/watch. This can supply invaluable data for doctors to analyse and discover any correlations between these parameters. An Android-based toolset has been developed to help reduce the effort required for hardware engineers to design new sensory tags by investigating which tag architectures match the requirements of throughput, complexity and energy consumption. On the functional blocks level, a few novel topologies have been researched, implemented and tested, including a particular amplitude shift keying (ASK) demodulator and sensor readout for specific nanowire (NW) biosensors using time to digital conversion (TDC).