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High-performance dual-gate graphene pH sensors



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


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.
Applied Physics Letters


graphene, biosensors, field-effect transistors


Le, S. , Cho, S. , Zaslavsky, A. , Richter, C. and Balijepalli, A. (2022), High-performance dual-gate graphene pH sensors, Applied Physics Letters, [online],, (Accessed July 20, 2024)


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Created June 28, 2022, Updated November 29, 2022