Wireless hydrogel-based glucose sensor for future implantable applications

Abstract

This paper presents a hydrogel-based glucose sensor for future implantable applications employing an inductive sensing technique. The prototype system is based on an ultra-low power tunnel diode oscillator employing a 2 mm-diameter/10-turn sensing coil enclosed in a 3D-printed sealed sensor package. A 3 mm × 3 mm × 80 μm metallic sensing plate embedded in a 3 mm × 3 mm × 400 μm glucose-sensitive hydrogel slab is positioned at 130 μm away from the sensing coil by using an adjustable platform in the prototype design. The small gap is critical for a high sensitivity. The oscillator achieves a 38 MHz nominal frequency while dissipating 40 μW. Under a stable DC power supply, the sensor demonstrates a sensing accuracy around 0.2 mM in human physiological glucose range.