A high-performance amperometric biosensor system utilizing electrolytic gas bubbles

Most of the biochemical sensors exhibit instabilities such as baseline drift and sensitivity degradation. An on-demand in situ self-diagnosis and self-calibration functionality of biochemical sensors is indispensable for continuous and reliable monitoring. An on-chip electrochemical actuation method (water electrolysis) was employed to achieve this novel functionality. New integrated microfluidic systems are proposed for intelligent glucose and lactate monitoring. The oxygen microenvironment created by the electrolytic bubbles provides novel functionalities to glucose and lactate sensors: the one-point in situ self-calibration (zero-point), extension of dynamic range, and increase in sensitivity. The properties of electrolytically generated gas bubble were first investigated with a commercial fiber optic oxygen sensor. A microsystem including a fluidic structure and electrolysis electrodes is prepared by microfabrication technologies. A thick photoresist was used to prepare a template for the molding process of a polydimethylsiloxane (PDMS) cover layer to define the fluidic structure. The electrode substrate was a silicon wafer with a silicon nitride layer coating. The controlled oxygen microenvironment effectively manipulated the sensor responses. This electrochemically-driven fluidic biosensor system appears to be a promising platform of minimally invasive biosensing devices or extracorporeal devices for continuous monitoring due to its simple and miniaturized structure --Abstract, page iii