Strong Bacterial Cellulose-Based Films with Natural Laminar Alignment for Highly Sensitive Humidity Sensors

Humidity
sensors have been widely used for humidity monitoring
in industry and agriculture fields. However, the rigid structure,
nondegradability, and large dimension of traditional humidity sensors
significantly restrict their applications in wearable fields. In this
study, a flexible, strong, and eco-friendly bacterial cellulose-based
humidity sensor (BPS) was fabricated using a two-step method, involving
solvent evaporation-induced self-assembly and electrolyte permeation.
Rapid evaporation of organic solvent induces the formation of nanopores
of the bacterial cellulose (BC) surface and promotes structural densification.
Furthermore, the successful embedding of potassium hydroxide into
the sophisticated network of BC effectively enhanced the sensing performance
of BPS. The BPS exhibits an excellent humidity sensing response of
more than 103 within the relative humidity ranging from
36.4 to 93% and strong (66.4 MPa) and high flexibility properties
owing to the ultrafine fiber network and abundant hydrophilic functional
groups of BC. Besides being strong and thin, BPS is also highly flexible,
biodegradable, and humidity-sensitive, making it a potential candidate
in wearable electronics, human health monitoring, and noncontact switching.