A capacitively based MEMS affinity glucose sensor

This paper presents a capacitively based MEMS affinity sensor for continuous glucose monitoring applications. This sensor consists of a vibrating Parylene diaphragm, which is remotely driven by a magnetic field and situated inside a microchamber. A solution of poly(acrylamide-ran-3-acrylamidophenylboronic acid) (PAA-ran-PAAPBA), a biocompatible glucose-sensitive polymer, fills the microchamber, which is separated from its surroundings by a semi-permeable membrane. As glucose concentration is varied, viscosity changes induced by glucose/polymer binding cause a detectable change in the Parylene diaphragm vibration which can be measured capacitively. The response time of the sensor to glucose concentration changes is approximately 3 minutes which can be further improved with optimized device designs. The device has been tested at physiologically relevant glucose concentrations ranging from 27 to 324 mg/dL, showing excellent reversibility and stability.