Graphene Gas Osmometers

TL;DR

This paper demonstrates that graphene membranes can act as sensitive gas osmometers by detecting osmotic pressure differences caused by varying gas permeation rates, enabling nanoscale pressure measurements.

Contribution

It introduces a novel graphene-based gas osmometer that measures osmotic pressure differences through membrane deflection and resonance frequency shifts.

Findings

Large differences in osmotic pressure for different gas pairs.

Responsitivity of ~60 kHz/mbar for the graphene osmometer.

Nanoscale dimensions enable high sensitivity and small-scale measurements.

Abstract

Here it is shown that graphene membranes that separate 2 gases at identical pressure are deflected by osmotic pressure. The osmotic pressure is a consequence of differences in gas permeation rates into a graphene enclosed cavity. The deflection of the few layer graphene membranes is detected by an interferometric technique for measuring their tension-induced resonance frequency. Using a calibration measurement of the relation between resonance frequency and pressure, the time dependent osmotic pressure on the graphene is extracted. The osmotic pressure for different combinations of gases shows large differences that can be accounted for by a model based on the different gas permeation rates. Thus a graphene membrane based gas osmometer with a responsitivity of ~60 kHz/mbar and nanoscale dimensions is demonstrated.