Abstract
Dual-gate (DG) Ion-sensitive thin-film transistor (ISTFT) pH sensors based on tin oxide (SnOx) channel and Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> sensor membrane have been developed. DG SnOx thin film transistors with Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> dielectrics were fabricated, illustrating effective linear current modulation under top gate bias. The SnOX DG-ISTFTs with 10-nm Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> sensor membrane can operate at a low single supply voltage of -1.0 V with a low power consumption around 3 μW. In contrast to most reported ISTFT pH sensors, which show linear dependence of pH value on threshold voltage, and are not directly readable, the SnOx DG-ISTFTs exhibit linear pH dependence on directly readable drain current. We demonstrate a high sensitivity of 83.87 nA/pH and a low current hysteresis of 1.65 nA after a pH loop of 7-10-7-4-7. This enables significantly simplified readout circuits with reduced power consumption. The SnOx based DG-ISTFTs may have huge practical potential as portable and wearable biosensors and chemical sensors.
Published Version
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