Quantifying the effect of ionic screening with protein-decorated graphene transistors

TL;DR

This study investigates how ionic screening affects protein-decorated graphene FETs by quantitatively analyzing the gating effect of charged biomolecules in ionic solutions, advancing understanding for biosensing applications.

Contribution

The paper introduces a quantitative model that accurately describes ionic screening effects on protein-decorated graphene FETs, linking biomolecular charge to electrical readout.

Findings

Excellent agreement between experimental data and the model

Quantitative understanding of ionic screening effects

Coupling biomolecular charge to FET readout

Abstract

Liquid-based applications of biomolecule-decorated field-effect transistors (FETs) range from biosensors to in vivo implants. A critical scientific challenge is to develop a quantitative understanding of the gating effect of charged biomolecules in ionic solution and how this influences the readout of the FETs. To address this issue, we fabricated protein-decorated graphene FETs and measured their electrical properties, specifically the shift in Dirac voltage, in solutions of varying ionic strength. We found excellent quantitative agreement with a model that accounts for both the graphene polarization charge and ionic screening of ions adsorbed on the graphene as well as charged amino acids associated with the immobilized protein. The technique and analysis presented here directly couple the charging status of bound biomolecules to readout of liquid-phase FETs fabricated with graphene or other two-dimensional materials.