Application of Indium Oxide Flexible Humidity Sensor in Skin Breath Detection

The indium oxide (In
2
O
3
) humidity sensing material was grown on a silicon buffer epilayer, and then the indium oxide metal oxide semiconductor (In
2
O
3
MOS) sensing structure was fabricated for an In
2
O
3
MOS skin surface breath sensor on a flexible polymer substrate to have the sensitive breathing sensing properties. A DC magnetron sputtering system was used to complete all the processes for the fabrication of the skin respiration sensor. After completing the fabrication of the indium oxide humidity sensing layer (In
2
O
3
HSL), a Hall measurement system was used to measure the electrical properties of the indium oxide sensing layer. Secondly, after completing the fabrication of the relative humidity sensing device, the LCR meter was used to measure the performance of the humidity sensing device. Finally, the humidity sensing device was placed on the skin surface to make the skin respiration sensing, and then the LCR meter was used for detecting human skin surface breath. According to the research results, both the capacitance adsorption and the capacitance desorption sensitivities of the humidity sensing device were about 0.046. The adsorption linearity and the desorption linearity for capacitance value were, respectively, 1.5 and 3.1. The capacitance adsorption responsivity and the desorption responsivity are respectively 68 and 54.5 s. Eventually, the skin respiration before and after exercise was examined by using the In
2
O
3
MOS skin surface breath sensor. The sensitivities of the skin respiration detection are respectively about 0.036 for human skin respiration before exercise and about 0.162 for post-exercise.