Noise Reduction of Amperometric Electrochemical Sensor using Current Compensation on Transimpedance Amplifier for Dissolved Oxygen Measurement

In this paper, a study of noise reduction of an electrochemical sensor is presented. This study is initiated based on the fact that the signal from the electrochemical sensor has quite high noise. The current signal from the sensor is very weak and noisy due to high impedance and complex process on the sensor and measured media such as a solution of dissolved oxygen. The current is usually converted using a transimpedance amplifier with high voltage-to-current ratio by a feedback resistance, which usually also produces large noise due to high feedback resistance value. This will contribute to an additional noise to the natural noise of the sensor and measured media, causing more noisy result. A modified transimpedance amplifier is proposed to reduce the noise from the sensor and converter to increase signal-to-noise ratio. The modification employs a current compensation, so that the current noise is suppressed at the converter input. The noise and signal measurements at the output of the compensated transimpedance amplifier show noise reduction compared to the standard transimpedance amplifier and measurement error reduction of the measured dissolved oxygen down to 0.89%.