Self-adhesive and Ultra Elastic Dual-mode Flexible Sensors from Conductive Hydrogels

Electronic skin (e-skin) has diverse applications in motion detection, disease diagnosis, soft robotics, and humancomputer interaction. Magnetic sensing is an effective method for non-contact sensing of e-skin that has gained much attention due to its inherent specificity to magnetic substances and antiinterference properties. In this work, we have successfully developed non-contact magnetic and strain-sensitive dual-mode stretchable hydrogel sensors. By a scalable one-pot polymerization process, we have successfully prepared a ferrosoferric oxide nanoparticles composite polyacrylamide/ hydroxypropyl cellulose hydrogel. The hydrogel exhibited large stretchability (a maximum strain of $\mathbf{2 5 8 4 \%}$), high toughness ($\mathbf{2. 4 4} \mathbf{~ M J} / \mathbf{m}^{3}$), and self-adhesive ability to different surfaces of the comment electronic substrates. It also showed high sensitivity to strain and deformation caused by magnetic-induced non-contact forces and external mechanical stimulation. Fast response (0.46 s) and recovery time (0.58 s), and the frequency tolerance sensing from 0.5 Hz to 2.0 Hz were overserved. This work shows the great potential of the high in the fields of soft robots, health and motion monitoring, humanmachine intelligent interfaces, and smart electronics.