Label-free electronic detection of biomolecules using a-Si:H field-effect devices

Abstract Electrolyte-gate amorphous silicon thin-film transistors (EG-TFT) are used for pH and label-free sensing of biological molecules. In top-gate EG-TFTs, the metal gate is replaced by an electrolyte solution, in which a biasing Pt electrode is immersed. It is possible to switch the TFT on by increasing the voltage of the Pt electrode above a threshold value ( V T ). EG-TFTs show a decrease in V T when the pH of the electrolyte solution is increased. EG-TFTs also show a shift in V T when exposed to solutions containing molecules of either DNA ( V T decreases) or the protein horseradish peroxidase (HRP) ( V T increases). Exposure to these solutions results in the adsorption of biomolecules at the dielectric-electrolyte interface which changes the TFT transfer curve and consequently allows electronic label-free detection of the biomolecules.