Flexible Electronic Skin Based On Temperature Sensors

Electronic skins based on flexible temperature sensors have been widely concerned in the application fields of wearable human activity monitoring equipment and personal medical health.However,there are still many challenges to be solved in the field of electronic skins research,such as improving the stability of the devices,improving the sensitivity of the devices and reducing the cost.The temperature sensors based on thin film transistors have a good repeatability,high stability and high sensitivity,so the temperature sensors have great potential in the field of electronic skins.In this paper,based on the working principle of the transistors,indium-gallium-zinc-oxide was used as the semiconductor layer material of the devices,and simple processes such as magnetron sputtering and spin coating were selected to prepare the temperature sensitive amorphous oxide semiconductor thin film transistor sensors.In order to carry out corresponding application research in the field of artificial electronic skin,the temperature response characteristics of flexible devices were discussed in depth.Firstly,the flexible transparent devices were fabricated using simple processes,such as magnetron sputtering and spin coating.The operating voltage,switch ratio,field effect mobility and subthreshold swing of the devices are 1.1 V,2.81×10⁷,33.5cm²/V?s and 83.38 mv/dec,respectively.The flexible transparent devices have good transfer characteristics and output characteristics,and it was found that the threshold voltage V_TH of the devices have a strong correlation with the external temperature.At the same time,the correlation model between the output characteristic curve and the temperature was established.In addition,the temperature sensitivity,field effect mobility and the overall transparency of the flexible transparent devices are tested.Secondly,the mechanical flexibility of the flexible transparent thin film transistors was tested.Excellent transfer characteristic curves were achieved under two bending directions and different bending radii.On the test platform with downward and upward bending,the bending radius changes from 18 mm to 48 mm,the rate of change of the threshold voltage V_TH is 0.063%and 0.353%?<1%?,respectively.The results show that the flexible TFT has excellent mechanical flexibility.The bending endurance of the devices were tested with a 5 mm radius repeated bending equipment.After 10000bending tests,the threshold voltage V_TH increased slightly from 1.08 V to 1.16 V,the rate of change is 0.002%?<1%?,indicating that the flexible transparent devices have an excellent deformation stability.Finally,the temperature sensing mechanism of TFT devices was explained by cyclic bias test and energy band defect density of state test.When the external temperature changes,the thermally excited oxygen atom causes the vacancy,and the thermally excited oxygen atom leaves the initial position and enters the gap position.At the same time,the free electrons generated by the oxygen vacancy at a higher temperature reduced the threshold voltage V_TH.When the temperature decreases,the oxygen vacancy and the interstitial oxygen atom recombined with each other and return to the initial quasi equilibrium state.