Development of Amplified Redox Sensor Suitable for Onsite Measurement

Abstract

The redox sensor is a type of electrochemical sensors that can detect chemical substances from redox response derived from the characteristics of the substance. Redox sensor is attractive due to their fast response, sensitivity, simplicity and miniaturization. Therefore, redox sensor is expected to be applied to onsite monitoring. However, the redox output current is reduced if the sensing area is small and/or the concentration of the sample is low. We proposed an amplified redox sensor (ARS), which combines the sensing area that serves as a working electrode with a bipolar transistor. For onsite detection, portable small size device that can measure even small concentrations is required. In this paper, we report the performance limit of our proposed ARS from input referred current noise that we calculated from measurement conditions of cyclic voltammetry and square wave voltammetry using potassium ferricyanide. In addition, we compared to MOSFET based transimpedance amplifier of a single element. As a result, bipolar transistor based the ARS can expect low detection limit about 2 orders of magnitude lower. Hence, we believe that the proposed amplified redox sensor devices can be used in high sensitivity on-site monitoring in electrochemical measurements.