Flexible humidity sensors for wireless monitoring based on electrospun sulfonated polyether ether ketone (SPEEK) nanofibres

摘要

The development of flexible and high-performance humidity sensors for continuous wireless monitoring is receiving increasing attention. In this work, electrospun sulfonated polyether ether ketone (SPEEK) nanofibres with different sulfonation degrees were prepared and directly deposited onto flexible substrates for humidity sensor applications. On a logarithmic scale, both resistance (R_(dc)) and capacitance (C_s) of the SPEEK nanofibre-based sensors showed linear responses to changes between 30 and 80 % in relative humidity (RH). Our devices showed higher sensitivities (up to LogR_(dc)(Ω)/RH(%) = -0.06952 and LogC_s(F)/RH(%) = 0.07078) and improved linearity (over 0.980) than humidity sensors using continuous SPEEK films. The humidity sensors exhibited fast sensing responses (75 s), mechanical flexibility and durability. These beneficial properties can be attributed to the fibrous structure of electrospun SPEEK. The potential of SPEEK fibre-based humidity sensor was further demonstrated by monitoring real-time humidity levels using a printed near-field communication (NFC)-enabled circuit for wireless sensing.