Calibration‐Free and Highly Sensitive Potentiometric Enzyme‐Based Biosensors

Enzyme-based amperometric biosensors have become popular for healthcare applications. However, they have been under constant pressure for technological innovation to improve their sensitivity and usability. An ideal biosensor has high sensitivity and calibration-free characteristics. This study aims to report enzyme-based glucose and lactate sensors that utilize a proposed "time-derivative of potential (dOCP/dt)" method, with a further aim being to prove theoretically and experimentally that dOCP/dt values are proportional to substrate concentration. High sensitivity is obtained regardless of the electrode size because the electrode potential is independent of the electrode area in the biosensor. Importantly, because the substrate diffusion determines the enzyme reaction rate on the sensors, the dOCP/dt biosensors can essentially eliminate external influences such as temperature and pH. The result is the successful realization of a biosensor that is calibration-free, making it a much more practical option.