A differential light addressable potentiometric sensor using solid-state reference

The differential light addressable potentiometric sensor (LAPS) can provide low-background measurement for chemicals. For the conventional differential LAPS system, the acquisition of reference signal requires liquid participation. In this study, a differential LAPS with solid-state reference (SSR) is presented for pH measurement, where SSR based on the structure of metal-insulator-semiconductor is used as reusable reference signal source. In order to facilitate the differential signal matching and realize the effect of large reduction of background signal, an intelligent method to match the amplitude and phase between LAPS output and SSR output by controlling the illumination excitation of SSR is proposed. Effect of SSR as reference signal source for differential LAPS is studied, which is including pH sensing and chemical image performance. As an auxiliary liquid-free chip, SSR can assist the differential LAPS to realize low-background pH measurement conveniently and flexibly.