Highly sensitive microelectrode for glucose sensing via inkjet printing technology

The increasing demands in diagnostic devices require biosensors with fast and accurate detection. In this research, we demonstrate a physical surface modification method to create bio-sensors with a layer-by-layer strategy. First, a mediator layer (Prussian Blue (PB)) was inkjet-printed on a screen-printed carbon electrode. An enzymatic layer (Glucose Oxidase) was then printed on top of the mediator layer. Finally, an entrapment layer (Wax) was printed above to immobilize oxidases. In particular, the patterns or sizes of the sensors were adjusted by this direct-writing method to fabricate micro-electrodes. Electrochemical tests, such as cyclic voltammetry and chronoamperomtry, were used to characterize the sensor capability on glucose detection. The sensor sensitivity increases with smaller electrode sizes and can be up to 50 mA/cm²/mM, which is at least 25 times larger than any PB-based glucose sensors in the literature. This approach can be further extended to many other bio-chemical detections, such as cholesterol and neurotransmitter, for health care or food security.