Fig. 4: An experimental setup for removing the displacement current.

a Displacement current signals induced by electromechanical actuation with or without light irradiation, averaged from two cycles of the signal. b An experimental setup for removing the displacement current signal by the differential amplifier. The function generator emulates the displacement current signal by generating a prerecorded signal without light irradiation, and the photocurrent is extracted from the mixture signal of the photodetector by the differential amplifier