Fully printed Biodegradable Nanocellulose-Based Humidity Sensor for SMART LABEL Applications

摘要

Resistive-type humidity sensors were fabricated by using nano- (NFC) or microfibrillar cellulose (MFC) as a sensing layer and printing substrate at the same time. The variation of impedance within a range 20-90 % of relative humidity was measured across a printed carbon based interdigitated structure. The NFC-based sensors exhibit logarithmic sensitivity to moisture up to 75 % RH, beyond which saturation is observed. The MFC-based sensors have proper sensitive behaviour in the range 40-90 % RH. Based on the results, it is obvious that sensor behaviour is controlled by the differences surface chemistry and nanoscale fibrillar structure of the cellulosic materials, which lead to differences in interaction with moisture. The response of sensors in the whole range of RH can potentially be optimized by proper combination of both types of cellulose materials.