Graphene Transistor as a Probe for Streaming Potential

TL;DR

This paper demonstrates that graphene transistors can serve as sensitive probes for fluid flow and ionic concentration by detecting shifts in electrical properties caused by streaming potentials, enabling precise sensing.

Contribution

It introduces a novel application of graphene transistors as flow and ionic sensors based on electrochemical potential variations near the device.

Findings

Detects flow rates as low as 70 nL/min

Measures ionic concentration changes as small as 40 nM

Shows reproducible shifts in charge neutrality point related to fluid flow

Abstract

We explore the dependence of electrical transport in a graphene field effect transistor (GraFET) on the flow of the liquid within the immediate vicinity of that transistor. We find large and reproducible shifts in the charge neutrality point of GraFETs that are dependent on the fluid velocity and the ionic concentration. We show that these shifts are consistent with the variation of the local electrochemical potential of the liquid next to graphene that are caused by the fluid flow (streaming potential). Furthermore, we utilize the sensitivity of electrical transport in GraFETs to the parameters of the fluid flow to demonstrate graphene-based mass flow and ionic concentration sensing. We successfully detect a flow as small as~70nL/min, and detect a change in the ionic concentration as small as ~40nM.