Multifunctional polyacrylamide-gelatin deep eutectic gel with integrated antibacterial, antifreezing, and conductive properties for wearable motion sensing.

Traditional sensors, in long-term skin contact, prone to microbial growth, risking skin allergies and infections. To address this issue, a novel deep eutectic gel composite-polyacrylamide-gelatin-Dalbergia benthamii Prain total flavonoids (PAMG-DbTF)-was developed by integrating betaine-urea-based natural deep eutectic solvent (NADES) with polyacrylamide (PAM) and gelatin-a biopolymer derived from collagen-via physicochemical crosslinking. As the core biopolymer, gelatin played a pivotal role in constructing the stable interpenetrating network: its intrinsic amino acid residues formed hydrogen bonds with PAM chains and NADES, which was confirmed by FT-IR, SEM, XRD, XPS and TGA analyses. This gelatin-driven network endowed the gel with excellent mechanical and stability properties, including a tensile strain of 330%, a swelling ratio of 220%, 90% water retention at 48 h, and antifreezing performance at -20°C. The DbTF-loaded gel showed synergistic antibacterial activity (100% against E. coli) and antioxidant capacity (70% DPPH scavenging rate). As a flexible strain sensor, PAMG-2 demonstrated stable relative resistance changes (ΔR/R0) under cyclic loading (500 cycles at 40% strain) and real-time monitoring of human motions (throat vocalization, joint bending), where gelatin's elasticity ensures signal repeatability. This gelatin-centered multifunctional deep eutectic gel highlights the critical role of biopolymers in advanced wearable biomedical devices and environmental monitoring.