Highly Sensitive Temperature Sensor Using Low-Temperature Polysilicon Oxide Thin-Film Transistors

We report highly sensitive temperature sensing circuits using low temperature polysilicon oxide (LTPO) thin-film transistors (TFTs) on a glass substrate. The sensor has the LTPO operational amplifier (Op-Amp) made of dual gate (DG) amorphous InGaZnO (a-IGZO) and low temperature poly-Si (LTPS) TFTs by blue laser annealing process. The DG a-IGZO TFTs-based sensing circuit exhibits a sensitivity of 37.9±3 mV/°C and it can be further boosted to 223.33±8 mV/°C by incorporating LTPO Op-Amp for body temperature detection (35~40 °C). The DG a-IGZO TFT exhibits robust threshold voltage stability (
$\Delta {\rm V}_{Th}$
= −0.16 V) with temperature, which is essential for the practical development of the proposed LTPO differential temperature sensor (TS) to accurately measure the human body temperature.