Construction and mechanism of konjac glucomannan-based laminated flexible sensor hydrogel

Flexible hydrogel-based sensors show great potential but face challenges in dehydration for long-term storage and customization for various deformation measurements. This work reports a strategy for preparing hydrogel sensors by creating dry sensor films with different properties, which are rehydrated and laminated for specific applications. A polyhydroxyalkanoate (PHA) nanofiber membrane, produced via microfluidic bubble spinning and combined with conductive MXene, achieved a Young's modulus of 46.59 MPa. A biomass polysaccharide hydrogel made from konjac glucomannan, xanthan gum, and sodium alginate (SA) encapsulated the PHA/MXene membrane. The Young's modulus and load testing of the hydrogel sensors can be adjusted by varying SA concentration. The gel-encapsulated films can be dried for long-term preservation. For applications, the dried layers with different SA concentrations were rehydrated and assembled according to load requirements. Crosslinking between Ca 2+ ions and SA's carboxyl groups ensures stable interlayer bonding. Numerical simulations showed that the laminated sensor, combining soft and hard layers, responds well to various external forces. The laminated sensor captured multiple electrical signals to differentiate shear and compressive loads, which is a challenge for traditional flexible devices. This study presents a customizable laminated sensor that can be tailored to specific measurement ranges, enhancing hydrogel-based sensing technologies.