A temperature sensor based on flexible substrate with ultra-high sensitivity for low temperature measurement

In this paper, indium oxide (In₂O₃) and platinum (Pt) are selected as thermoelectric materials to form a kind of temperature sensor. The thermoelectric property of In₂O₃ is optimized by heat treatment that the Seebeck coefficient is greatly increased with the increase of heat treatment time at 200°C. The sensitivity of the flexible thin film thermocouples combined with Pt increased from -40.43μV/°C to -176.06μV/°C with the same temperature difference between hot junction and cold junctions, increasing by 4.35 times. The treated flexible Pt/In₂O₃ TFTCs based on polyimide exhibits a maximum output voltage of 34.33mV and an ultra-high sensitivity of 204.35μV/°C, which is one of the highest values reported for thermocouples deposited onto flexible substrate in the low temperature measurement. In repeatability test and stability test, the sensor also shows great characteristics in repeatability, stability and the temperature drift. In practical manipulator measurement, it can realize accurate measurement of the temperature of the measured object, which has an excellent application prospect of industrial robot and biomedicine.