A low power miniaturized CMOS-based continuous glucose monitoring system

This paper presents the design and fabrication of a highly-miniaturized system for continuous glucose monitoring which holds great promise for patients inflicted with diabetes mellitus. To achieve the realization of a truly implantable system, a variety of issues such as robust electrochemical sensor design, miniaturization of the electronic components and counteracting biofouling and negative tissue response need to be addressed. In this report, we present a highly-miniaturized transcutaneous continuous glucose monitoring system which holistically addresses the aforementioned tribulations associated with implantable devices. Specifically, a high performance amperometric electrochemical glucose sensor is integrated with custom designed complementary metal-oxide-semiconductor electronics. The fabricated electrochemical sensor is Clark-based, and employs stratification of five functional layers to achieve a linear response within the physiological range of glucose concentration (2–22 mM). Furthermore, the sensor is encased with a thick polyvinyl alcohol (PVA) hydrogel containing poly(lactic-co-glycolic acid) (PLGA) microspheres which provides continuous, localized delivery of dexamethasone utilized to combat inflammation and fibrosis. Such miniature size (0.665 mm2) and low power operation (140 μW) of the electronic system render it ideal for continuous glucose monitoring devices and other metabolic sensing systems.