High sensitive and fast response humidity sensor based on polymer composite nanofibers for breath monitoring and non-contact sensing

Abstract

A rapid and stable polymeric humidity sensor is demonstrated using electrospun sulfonated poly (ether ether ketone)/polyvinyl butyral (SPEEK/PVB) composite nanofiber and applied in breath monitoring and non-contact sensing for the first time. First, SPEEK was fabricated into thin film sensor by drip casting and nanofiber sensor by electrospinning, respectively. By comparing the humidity sensing characteristics of the two sensors, it is found that the hysteresis and response/recovery time of the nanofiber humidity sensor have been significantly improved. To further improve its sensing performance, we incorporated different contents of polyvinyl butyral (PVB) to the electrospinning solution to prepare SPEEK/PVB composite nanofiber humidity sensors. The morphology and diameter of nanofibers with different PVB contents were observed by Scanning Electron Microscope. The composite nanofiber humidity sensor exhibited high sensitivity, wide working range of relative humidity, small hysteresis (2.68 %), fast response time (<1 s), rapid recovery time (5 s) and stable sensing performance when the ratio of SPEEK to PVB is 1:3. In addition, the breath monitoring and non-contact sensing performance of SPEEK/PVB = 1:3 composite nanofiber humidity sensor was also studied. This work indicates that electrospun SPEEK/PVB nanofibers have good application prospects as humidity sensors for real-time humidity monitoring and non-contact sensing devices.