Rehydrated laminate-assembled hydrogel: a universal platform for scalable and tailorable multifunctional sensor systems

Abstract

Hydrogel sensors have immense potential for application in fields such as flexible wearable devices. However, hydrogel sensors still face challenges related to process scalable fabrication, convenience of long-term storage, customization for diverse application scenarios, and ease of modular functionalization. In this study, a sustainable manufacturing strategy for the rapid rehydration of prefabricated multifunctional gel dry films and modular assembly to form multifunctional multilayer hydrogel devices is reported. First, the developed fully biodegradable biomass polysaccharide encapsulation composite, konjac glucomannan/sodium alginate/dopamine (KSD) derived from renewable resources, was utilized to encapsulate various functional materials separately and then dried to form prefabricated parts of various functional hydrogel dry films. In the application of the device, through the gel rehydration and water-triggered hydrogel interlayer metal–ligand chelation bonding, the personalized modularly functionalized hydrogel devices can be assembled quickly and conveniently according to the application requirements while minimizing material waste. The binding between the hydrogel layers occurs through the formation of metal–ligand bonds between the calcium ions in the solution and the carboxylic acid groups in sodium alginate, which results in an interlayer bond strength of 0.57 MPa after only 1.5 min. Moreover, a KSD-encapsulated anisotropic flexible thermoplastic urethane/MXene (TPU/MXene) conductive gel dry film was constructed, and multilayered anisotropic hydrogel flexible sensors were assembled by the rapid rehydration and lamination of the gel dry film. The multilayer composite hydrogel can accurately recognize complex deformations such as curved surface motion through multiple signals, which is difficult to realize by using ordinary sensors. Moreover, the bacteriostatic functional layer can be conveniently integrated on top of the flexible conductive sensing layer based on the circular design principle of the modular assembly strategy. The pH-responsive bacteriostatic membrane ZIF-8/flavanone/KSD prepared using the microfluidic and mosaic encapsulation methods displays satisfactory biocompatibility and bacteriostatic properties. The strategy of rapid rehydration and lamination of prefabricated parts of several functional dry gels for customized modular assembly proposed in this paper will enable resource-efficient scalable batch fabrication of prefabricated parts for flexible hydrogel sensors and extended product lifespan through in-demand functional upgrades, accelerating the development of sustainable wearable technologies.