Bacterial cellulose/MWCNT coatings for highly sensitive and flexible paper-based humidity sensors

As a human-computer interaction technology for the Internet of Things (IoT), non-contact humidity sensors have been widely explored. However, traditional humidity sensors have become a bottleneck in the development of flexible electronics owing to their complex processes and non-degradability. Here, bacterial cellulose (BC) and MWCNT were sequentially coated on paper to construct a durable and highly sensitive bacterial cellulose/MWCNT humidity sensor (BCNT). The BC endows the paper substrate with dense structure and significantly reduces the consumption of active materials (6.7 times reduction). Further, the well-dispersed CNT coating forms an interlocking structure with the BC nano-network, which results in a high mechanical strength (66.3 MPa). The maximum response of BCNT02 can be up to 94.5% (− ΔI/I0) under 98% RH, and the response and recovery times were 150 and 297 s, respectively. Moreover, the high humidity sensitivity of the BCNT make it an excellent choice for research and development of humidity sensors for respiration detection, non-contact switching and humidity localization.