Fig. 1.

Construction of graphene electrostatic wideband receiver (microphone). The graphene membrane is suspended across the supporting frame (A). The membrane is electrically contacted with gold wires, and spacers are added (B) to control the distance from the membrane to the gold-coated stationary electrodes (C). Operation principles: the microphone can be modeled as a current source i_mic. The conventional circuit (D) is not suitable for high-frequency operation because parasitic capacitance C_p is in parallel with the current–voltage conversion resistor R. The fast-photodiode detector-like circuit (E) avoids charging C_p and maintains a consistent gain at higher frequencies.