Electro-chemical sensor interface ICs for next-generation Point-of-Care and implantable electronics

Gastrointestinal (GI) diseases are quite common and can be very severe. For example, GI cancers account for up to 25% of all cancer deaths in developed countries and functional GI disorders bring significant inconvenience in daily life. Since the GI tract is the primary channel through which materials enter and exit the human body, it is also a great location for obtaining useful information related to a number of metabolic diseases. Current investigation of the GI tract or analysis of certain biomarkers usually happens via fecal sampling or endoscopic analysis, which are cumbersome and cannot be done at a regular intervals. Recently a number of smart electronic pills or implants to address these issues have emerged. However, the vast majority of these techniques focus on imaging, either visually with (RGB) cameras or with ultrasound which, while very useful, remain limited to detecting structural abnormalities like cancer or ulcers. However, functional GI diseases do not exhibit visually observable structural abnormalities. Therefore, there is a need for a class of devices that can detect other relevant biomarkers like GI pH, temperature, oxygenation, tissue impedance and the presence of various neurotransmitters and hormones along the full GI tract in an autonomic manner. The GI tract is especially interesting since it has significantly less stringent requirements in terms of bio-compatibility than typical implants. Hence such devices could be conceived as an ingestible pill or smart electronic implant small enough to be implanted via minimally invasive (endoscopic) procedures. However, the challenges are great. Of course, such devices must provide great sensitivity and reliability, with extreme power and size constraints. Recent advancements in electro-chemical sensors (ISFETs, ion-sensitive membranes, carbon-nanotubes, silicon nanowires, nanopores, etc.) enable the design of extremely miniaturized sensors which can be coupled with advanced ultra-low-power analog sensor interfaces and wireless links. This PhD will focus on the development of ultra-low-power electro-chemical sensor readout circuits. Various state-of-the-art sensor types (ISFET, CNT, ion-sensitive membranes, nanowires & nanopores, etc.) relevant for the above described application will be analysed for integration. A suitable readout circuit must be designed to interface with these sensors, overcoming the challenges (noise, drift, calibration, leakage, etc) from non ideality of the sensors. Once those electronic readouts have been validated, the whole concept will be integrated with the chosen sensors into an extremely miniaturized prototype. The design will then be validated in a realistic setting.