Ultrafast response flexible breath sensor based on vanadium dioxide.

Real-time monitoring of breath can provide clinically relevant information about apnea syndrome and other important aspects of human physiology. Here, we introduce a flexible skin-like breath sensor developed by transfer-printing vanadium dioxide (VO2) thin films on PDMS substrates. This flexible breath sensor can conformably laminate on the skin under the nose with different curvatures and operate at different environment temperatures through day and night. Attributed to the high temperature coefficient of resistance of VO2, the enhanced breath sensing performance was demonstrated and the response time and recovery time can be as fast as 0.5 s. The excellent sensing performance and fast response time indicate that the VO2-based breath sensor is feasible in monitoring breath for prevention of apnea syndrome.