High-performance dual-gate graphene pH sensors

Published

June 28, 2022

Author(s)

Son Le, Seulki Cho, Alexander Zaslavsky, Curt A. Richter, Arvind Balijepalli

Abstract

High precision biophysical measurements that are portable and performed without prior labeling of the molecules can greatly benefit several areas of biotechnology and biophysics, but existing techniques often lack sufficient resolution. Field-effect transistors (FETs) are versatile tools for measuring numerous biomarkers, and their measurement sensitivity and resolution can be improved by using new materials and device designs. Here, we report on the sensitivity and noise performance of dual-gated graphene FETs. As an example, when measuring pH, the devices exhibit a sensitivity of up to 30 V for a unit change in pH, about ≈ 500-fold greater than the Nernst value at room temperature, and a noise limited resolution of 2x10^-4 in the biomedically relevant bandwidth between 0.1–10 Hz. This high level of performance is obtained due to a highly asymmetric dual-gate design utilizing an ionic liquid top-gate dielectric coupled with graphene's large intrinsic quantum capacitance (15 µC/cm2), allowing a top-gate to back-gate coupling ratio of 500. Our results improve upon the both the sensitivity and resolution of previously demonstrated devices with MoS2 channel materials in a mature graphene-based technology.

Citation

Applied Physics Letters

Volume

120

Issue

26

Pub Type

Journals

Download Paper

https://doi.org/10.1063/5.0086049

Local Download

Keywords

graphene, biosensors, field-effect transistors

Citation

Le, S. , Cho, S. , Zaslavsky, A. , Richter, C. and Balijepalli, A. (2022), High-performance dual-gate graphene pH sensors, Applied Physics Letters, [online], https://doi.org/10.1063/5.0086049, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=933136 (Accessed October 17, 2025)