A hydrogel-based glucose affinity microsensor.

We present a hydrogel-based affinity microsensor for continuous glucose measurements. The microsensor is based on microelectromechanical systems (MEMS) technology, and incorporates a synthetic hydrogel that is attached to the device surface via in situ polymerization. Glucose molecules that diffuses into and out of the device binds reversibly with boronic acid groups in the hydrogel via affinity binding, and causes changes in the dielectric properties of the hydrogel, which can be measured using a MEMS capacitive transducer to determine the glucose concentration. The use of the in situ polymerized hydrogel eliminates mechanical moving parts found in other types of affinity microsensors, as well as mechanical barriers such as semipermeable membranes that are otherwise required to hold the glucose-sensitive material. This facilitates the miniaturization and robust operation of the microsensor, and can potentially improve the tolerance of the device, when implanted subcutaneously, to biofouling. Experimental results demonstrate that in a glucose concentration range of 0-500 mg/dL and with a resolution of 0.35 mg/dL or better, the microsensor exhibits a repeatable and reversible response, and can potentially be useful for continuous glucose monitoring in diabetes care.