The closed cavity resonator formed by graphene/PMMA for low frequency ultrasound detection

Abstract

A graphene/poly (methyl methacrylate) (PMMA) closed cavity resonator for low-frequency ultrasound (less than 200 kHz) detection has been fabricated. The 6-layer graphene with 450 nm PMMA laminated layer has been dry transferred onto the closed cavity with the air gap of 105 μm. The resonator has been actuated in atmosphere and room temperature by mechanical, electro-static and electro-thermal methods. The resonant frequency has been measured to be around 160 kHz. The (1,1) mode has been observed to dominate the resonance, which suggests the graphene/PMMA membrane has been perfectly clamped and seals the closed cavity. The degree of linearity of the membrane’s displacement versus the actuation signal has been determined. The resonant frequency has been observed to be tuned to about 4% by applying AC voltage through the membrane. The strain has been estimated to be around 0.08%. This research puts forward a sensor design for low-frequency ultrasonic detection.