A Low-Power Miniaturized Microelectronic System for Continuous Glucose Monitoring

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The design and fabrication of miniaturized, implantable, low-power wireless systems for continuous glucose monitoring hold great promise for diabetes mellitus inflicted patients. This involves addressing a variety of issues including extreme circuit miniaturization, robust electrochemical sensors as well as counteracting negative tissue response and biofouling following sensor implantation. In this contribution, we present a highly miniaturized microelectronic sensor platform that fits through a hypodermic needle and holistically addresses all aforementioned tribulations. For this, a custom designed complementary metal-oxide-semiconductor electronic device employing the 0.35 µm design rule has been integrated with a high performance amperometric electrochemical glucose sensor. The fabricated electrochemical sensor utilizes the stratification of five functional layers resulting in linear amperometric response within the physiological glucose range (2 – 22mM). 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 subsequent to implantation. In vivo evaluation in a rat has shown that this system accurately tracks glycemic events. Such miniature size and low power operation (0.665 mm2 and 140 µW, respectively) of the electronic system render it an ideal platform for continuous glucose monitoring and other metabolic sensing applications.