Surface Photovoltage-Based Biosensor

Abstract

The surface photovoltage (SPV) technique was first applied to a chemical sensor by Hafeman et al. in 1988.1 We applied the technique to immunosensors in 19902 and also investigated possible applications to various kinds of chemical sensors, including ion sensors,3 gas sensors,4 biosensors,5 and image sensors.6 These studies demonstrated various advantages of an SPV sensor over other chemical sensor: (1) the fabrication process is simple; (2) by multiplexing different light sources in different locations, the device can be a multisensor [light-addressable potentiometric sensors (LAPS)] without additional process complexity; and (3) encapsulation is easier and less critical. SPV also allows for flexibility in the signal processing method as it is based on ac measurements. For example, a differential measurement technique that we proposed made high-sensitive measurements possible by canceling out the common noise and drift component.3 These advantages also suggested that the SPV technique might be used to develop a new generation of chemical sensors, such as a highly integrated chemical and image sensor.