A microneedle-based glucose monitor: fabricated on a wafer-level using in-device enzyme immobilization

This paper presents a disposable minimally invasive self-calibrating continuous glucose monitor consisting of hollow out-of-plane microneedles to sample interstitial fluid from the epidermis, an integrated porous poly-Si dialysis membrane and an integrated enzyme-based flow-through glucose sensor. The proposed system can be fabricated on a wafer-level using standard MEMS technology and a novel in-device enzyme immobilization technique that allows wafer-level patterning of enzymes inside micro-scale flow channels after wafer bonding. This technique solves the compatibility issue of high temperature wafer bonding and temperature sensitive enzymes. A prototype of the glucose monitor is fabricated in order to demonstrate the high potential of out-of-plane microneedles for this application. Sampling of interstitial fluid through the microneedles results in a significant sensor response of the integrated glucose sensor.