Graphene Effusion-based Gas Sensor

TL;DR

This paper introduces a novel graphene-based gas sensor that uses effusion time constants to distinguish gases by molecular mass, offering a compact and low-power alternative to traditional spectrometry methods.

Contribution

The study demonstrates a new effusion-based gas sensing technique utilizing porous graphene membranes to differentiate gases by molecular mass through their permeation time constants.

Findings

Permeation time constants vary significantly among gases.

A linear relation exists between effusion time constant and square root of molecular mass.

The sensor is small, low-power, and suitable for practical gas detection applications.

Abstract

Porous, atomically thin graphene membranes have interesting properties for filtration and sieving applications because they can accommodate small pore sizes, while maintaining high permeability. These membranes are therefore receiving much attention for novel gas and water purification applications. Here we show that the atomic thickness and high resonance frequency of porous graphene membranes enables an effusion based gas sensing method that distinguishes gases based on their molecular mass. Graphene membranes are used to pump gases through nanopores using optothermal forces. By monitoring the time delay between the actuation force and the membrane mechanical motion, the permeation time-constants of various gases are shown to be significantly different. The measured linear relation between the effusion time constant and the square root of the molecular mass provides a method for sensing gases based on their molecular mass. The presented microscopic effusion based gas sensor can provide a small, low-power alternative for large, high-power, mass-spectrometry and optical spectrometry based gas sensing methods.