Nanoarchitectonics of high-sensitivity humidity sensors based on graphene oxide films for respiratory monitoring

Respiration monitoring is important for assessing human health, but most sensors have complex structures and processes. In this paper, the response of graphene oxide (GO) sensors with bottom- and top-connected structure to humidity is investigated for respiratory monitoring. The sensors of the bottom-connected structure increase the current by 132.97 % and 2077.55 % compared to those of the top-connected structure at GO concentrations of 25 mg/ml and 50 mg/ml, respectively. Both types of sensors can achieve corresponding responses to humidity (40 %-80 % relative humidity (RH)). The bottom-connected sensors, however, exhibit better performances with the responsivity of 96.25 % at 80 % RH and the sensitivity of 131.33 %/RH. In real -time monitoring for humidity, the bottom-connected sensors have good repeatability. The sensors can distinguish different breathing modes and detect the respiration rate/depth of the target. This provides an important method for the development of simple and fast humidity sensors.