3D-printable polyacrylamide/quaternary chitosan-based multifunctional hydrogel flexible sensors

Hydrogel-based wearable flexible pressure sensors show great potential for applications in human health and motion monitoring. However, fabricating hydrogel sensors with excellent mechanical properties, sensitivity, and stability remains challenging. In this study, we developed a poloxamer-quaternized chitosan-polyacrylamide (P407/QCS-PAAm) hydrogel with multifunctional capabilities. These hydrogels exhibit high strength, impact resistance, excellent electrical conductivity, hydrophilicity, and outstanding antimicrobial properties. Due to the dynamic hydrogen bonding provided by QCS, the mechanical properties of the hydrogel can be adjusted by regulating the QCS content, achieving tensile strengths ranging from 0.14 to 0.47 MPa and compressive strengths from 2.07 to 5.49 MPa. The quaternary ammonium groups carried by QCS enhance the gel's conductivity (0.29 S/m) and its bacteriostatic effects. Furthermore, the incorporation of P407 improves the hydrogel's hydrophilicity. These properties make the gel an excellent biosafety material for wearable devices. Notably, the hydrogel precursor exhibits rate-tunable sol-gel transition properties, enabling 3D printing. The 3D-printed P407/QCS-PAAm hydrogel sensors demonstrate high sensitivity (GF < −0.5) across a wide strain range (−40 % to 0 % strain). Considering these combined properties, the gel demonstrates significant potential for use in flexible wearable and 3D-printed electronic devices.