A multi-modal deformation sensing hydrogel with a nerve-inspired highly anisotropic structure†

Anisotropic hydrogel sensors have been widely applied in the field of smart devices, but there is still an increasing demand for flexible sensors that can sense three-dimensional mechanical changes and accurately capture complex behavior patterns. As a unique anisotropic biological structure, the peripheral nerve, consisting of bundles of nerve fibers arranged in parallel and enclosed by multiple layers of nerve membranes, exhibits high mechanical strength to resist external forces, rapid responsiveness to external stimuli, and the capability to swiftly transmit bioelectrical signals. Herein, inspired by peripheral nerves, a hydrogel with a multi-layer sandwich structure consisting of oriented fibers–pores–fibers was developed. Such advanced hydrogels exhibit impressive tensile breaking strength of 1.51 MPa and compressive stress of 3.51 MPa, with an ionic conductivity of 0.044 S cm⁻¹. When used as a sensor, the hydrogel possesses a three-dimensional response range, enabling it to simultaneously respond to mechanical changes in orthogonal directions, with good signal repeatability and high response sensitivity. These important capabilities enable the hydrogel to sense different movement patterns, accurately distinguish complex gaits such as walking, running, and jumping, and identify the force area on the sole of the foot. Therefore, the multi-modal deformation sensing hydrogel has great application potential in personalized health care and sports rehabilitation.