Transfer-free Graphene-based Differential Pressure Sensor

Graphene is an attractive material to be used for pressure sensors due to its thinness, electrical conductivity, and potential high gauge factor. One of the issues with processing graphene is the scalability, which is largely limited by the transfer process that is required for graphene deposited by chemical vapour deposition (CVD). In this work we employed a novel, transfer-free bulk-micromachining approach to realize graphene-based differential pressure sensors. The devices were successfully fabricated, and the samples were examined under Raman Spectroscopy, and electrically characterized. Further, pressure dependent measurements were performed for a dynamic range of 0 to 80 kPa of differential pressure and the corresponding change in resistance of the membrane was measured. The fabricated device has a sensitivity of 0.077 Ω/kPa and a gauge factor of 2.48.

I. Introduction

Graphene, first isolated in 2004, is a promising material in the world of microelectromechanical systems (MEMS) owing to its excellent mechanical, electrical, optical and chemical properties. The sp² hybridised C-C atoms form covalent bonds and these are responsible for its high in plane strength [1]. Some studies have shown CVD graphene to have a piezoresistive gauge factor around 10 [2]. These factors make graphene a promising material for highly sensitive pressure sensors.