Mechanoresponsive self-powered piezoelectric energy-generating composite hydrogels based on carbon nanotube-reinforced fungal-carboxymethyl chitosan-bacterial cellulose nanofibers for wearable electronics

Abstract

Developing conductive hydrogels with both enhanced mechanical properties and superior sensing capabilities for wearable, flexible electronics remains challenging. Here, we developed mechanoresponsive self-powered piezoelectric energy-generating composite hydrogels. These hydrogels were prepared by blending fungal-derived carboxymethyl chitosan (FC), carboxylate-bacterial cellulose nanofibers (CBC-NFs), and carbon nanotubes (CNTs) within a covalently crosslinked polyacrylamide (PAM) network (CNT-FBCNF). The resulting hydrogels showed remarkable mechanical properties due to the molecular interactions between polymer chains. The hydrogels showed a self-recoverable property and high stability under compressive mechanical force at 40% of strain (2000 cycles). The maximum compressive load (N) of 27.8 N was obtained for the optimized hydrogel, CNT-FBCNF (1% CNT content). This hydrogel exhibited a good conductivity of 1.3 S/m, which was attributed to the homogeneous dispersion of CNTs within the hydrogel matrix and sufficient biocompatibility with skin fibroblasts. The hydrogel also exhibited impressive performance as a strain sensor, boasting a wide strain range (10–40%), excellent stability, and repeatability. Furthermore, strategic cutting and assembly of the hydrogel generated a flexible strain sensor capable of accurately monitoring finger and thumb pressure in real-time. This study will significantly accelerate the development of hydrogel-based sensors within the rapidly advancing field of wearable soft electronics. Highlights: CNT-reinforced composite hydrogel was developed The optimized hydrogel showed good electrical conductivity (1.3 S/m) The optimized hydrogel showed good self-recovery properties The optimized hydrogel exhibited impressive strain-sensing capability between 10% and 40% strain.