Highly Sensitive Humidity Sensors Based on Pt Functionalized ZIF-67 Towards Noncontact Healthcare Monitoring

In order to enhance the sensitivity, Pt coated ZIF-67 was proposed to detect humidity levels for human physiological signal monitoring. The proposed capacitive humidity sensors have superior sensitivity of 44.9 pF/%RH for ZIF-67 with 10 nm Pt, which is about 7.8 times of ZIF-67 with 2 nm Pt and 4490 times of pure ZIF-67. The specificity of water toward 7 interferential volatile organic compounds (VOCs) was analyzed for biomarker discrimination. The proposed sensor exhibits high stability and repeatability in five cycle tests. Normal, fast, deep, and slow breath were investigated to record reading, running, yoga, and sleeping activities, respectively. In addition, the low humidity level evaporated by human sweat on the skin surface can be detected with high sensitivity. This paper provides a highly sensitive humidity sensor for daily clinical monitoring and intelligent health applications.