Enhancing the Detection Performance of Light-Addressable Potentiometric Sensor Using Efficient Light Source Excitation

Light-addressable potentiometric sensor (LAPS), as a potentiometric semiconductor field-effect electrochemical sensor with the advantages of high sensitivity, low cost, and simple fabrication, has been developed as an important tool for the label-free detection of biochemical species. An important challenge is that its output signal is small, its sensing capability and anti-interference capability are weak, and it needs to be further improved. In this paper, the effect of six typical waveforms as light-source excitations on the outputs, pH-sensing, and the resistance to noise interference of LAPS is innovatively investigated to seek efficient illumination. The frequency-dependent photocurrent, anti-interference capability, and pH-sensing of LAPS under different waveform excitation conditions are evaluated and compared. The experimental results show that LAPS using illumination excited with a square wave has the maximum photocurrent and signal-to-noise ratio, the enhancement ratio of the photocurrent close to the theoretical value, high sensitivity, and linearity compared to other waveform excitations. This simple and efficient illumination scheme will open new way for improving the detection performance of LAPS as well as biochemical sensors based on the semiconductor field effect principle.