A MEMS differential affinity sensor for continuous glucose detection

This paper presents a differential affinity sensor for continuous glucose monitoring. The sensor, based on microelectromechanical systems (MEMS) technology, consists of two magnetically driven vibrating diaphragms each situated inside a microchamber. The chambers respectively contain solutions of poly(N-hydroxyethyl acrylamide-ran-3-acrylamidophenylboronic acid) (PHEAA-ran-PAAPBA), a glucose-binding polymer, and poly(acrylamide) (PAM), a glucose-insensitive polymer. As glucose permeates through a semi-permeable membrane into each chamber, the viscosity of the PHEAA-ran-PAAPBA solution increases due to glucose binding, while the viscosity of the PAM solution is unchanged due to a lack of glucose binding. Measurement of the viscosity difference between the two chambers, via differential capacitive detection of the vibration damping, thus allows determination of the glucose concentration while rejecting viscosity changes caused by environmental fluctuations. In-vitro and in-vivo testing demonstrates the potential of the device to be used as a subcutaneously implanted sensor for continuous glucose monitoring.