Static capacitive pressure sensing using a single graphene drum

TL;DR

This paper presents a novel capacitive pressure sensor based on a single graphene drum with enhanced capacitance readout, capable of detecting very small capacitance changes and pressure differences.

Contribution

The authors develop a graphene-based capacitive pressure sensor with improved sensitivity by optimizing device architecture and reducing the gap size, enabling detection of minute capacitance and pressure changes.

Findings

Capacitance changes as small as 50 aF detected

Pressure differences as low as 25 mbar measured

Device design enhances capacitive responsivity at nanoscale

Abstract

To realize nanomechanical graphene-based pressure and gas sensors, it is beneficial to have a method to electrically readout the static displacement of a suspended graphene membrane. Capacitive readout, typical in micro-electro-mechanical systems (MEMS), gets increasingly challenging as one starts shrinking the dimensions of these devices, since the expected responsivity of such devices is below 0.1 aF/Pa. To overcome the challenges of detecting small capacitance changes, we design an electrical readout device fabricated on top of an insulating quartz substrate, maximizing the contribution of the suspended membrane to the total capacitance of the device. The capacitance of the drum is further increased by reducing the gap size to 110 nm. Using external pressure load, we demonstrate successful detection of capacitance changes of a single graphene drum down to 50 aF, and pressure differences down to 25 mbar.