A tough, stretchable, adhesive and electroconductive polyacrylamide hydrogel sensor incorporated with sulfonated nanocellulose and carbon nanotubes

Recently, hydrogel sensors have been widely applied in wearable and portable electronics, but the low mechanical property, intolerance of fatigue, and low sensitivity and adhesion limit their further applications. In this study, sulfonated nanocellulose (SCNF) with dual functionality was blended into polyacrylamide (PAM) hydrogel matrix to reinforce the mechanical strength and facilitate the homogeneous dispersion of carbon nanotubes (CNTs). The SCNF-CNT/PAM hydrogel was designed through free radical polymerization to achieve commendable mechanical, electrical, and multifunctional properties. The environmental-friendly SCNF serves as bio-templates to facilitate the assembling of CNT into integrated SCNF-CNT structures with good dispersity, thus enabling the establishment of an integrated conducting and reinforcing network. The fabricated SCNF-CNT/PAM hydrogel exhibited outstanding compressive strength (∼0.45 MPa at 50 % strain), tensile strength (∼169.12 kPa), and antifatigue capacity under cyclic stretching and pressing. Furthermore, the multifunctional sensors assembled using this hydrogel demonstrated high strain sensitivity (gauge factor ~ 3.7 at 100–400 % strain) and effectively detected human motions. This design principle provides promising prospects for constructing next-generation multifunctional flexible sensors, and the integration of these distinctive properties enables the prepared composite hydrogels to find potential applications in various areas, such as implantable soft electronic devices, electronic skin, and human movement monitoring.