Electrolyte-Gated Indium Oxide Thin Film Transistor Based Biosensor With Low Operation Voltage

In this work, we explore an In
₂
O
₃
-electrolytegated thin film transistor (In
₂
O
₃
-EGTFT) as a label-free biosensor. Through surface modification, the In
₂
O
₃
channel is coated by streptavidin, which serves as a receptor molecule. Then, the target biomolecules of biotin to be detected are captured by the receptor molecules. The charges in the target biomolecules would change the surface potential of the In
₂
O
₃
channel and result in the change of the EGTFT electrical performance. Here, the positive charges are observed in biotin, and the sensitivity is achieved as high as 150 Na/dec with ultralow operation voltage of V
_G
= 0 V and V
_DS
= 50 mV. The high background carrier concentration in the metal organic chemical vapor deposition (MOCVD) grown In
₂
O
₃
and huge electric double layer (EDL) capacitance in liquid gate could contribute to the ultralow operation voltage. The detection limit is ~50 ng/mL. This study demonstrates the feasibility of In
₂
O
₃
-EGTFT as biosensor, even though the detection limit should be improved.