All-Painting Process To Produce Respiration Sensor Using Humidity-Sensitive Nanoparticle Film and Graphite Trace

We propose an all-painting process to produce a respiration sensor made from a humidity-sensitive nanoparticle (NP) film and a graphite trace. The sensor is fabricated under ambient air with a simple vacuum-free process for green electronics: solely hand-painting on a cellulose acetate film. A humidity-sensitive silica NP film is painted by brush on pencil-trace graphite electrodes. An all-painted humidity sensor using this film shows 106% sensitivity within a 10–93% humidity change. The film is flexible and the humidity sensor operates as a respiration sensor after bending test. We design an all-painted respiration sensor using the humidity sensor and a painted resistor. Finally, we integrate the all-painted respiration sensor, a flexible temperature sensor, and a portable data logger as a portable bifunctional health-care device. The device on a mask can monitor human respiration rate and exhaled air temperature simultaneously.