Tendon-Inspired Anisotropic Hydrogels with Excellent Mechanical Properties for Strain Sensors.

Anisotropic conductive hydrogels mimicking the natural tissues with high mechanical properties and intelligent sensing have played an important role in the field of flexible electronic devices. Herein, tensile remodeling, drying, and subsequent ion cross-linking methods were used to construct anisotropic hydrogels, which were inspired by the orientation and functionality of tendons. Due to the anisotropic arrangement of the polymer network, the mechanical performance and electrical conductivity were greatly improved in specific directions. The tensile stress and elastic modulus of the hydrogel along the network orientation were 29.82 and 28.53 MPa, which were higher than those along the vertical orientation, 9.63 and 11.7 MPa, respectively. Moreover, the hydrogels exhibited structure-dependent anisotropic sensing. The gauge factors (GFs) parallel to the prestretching direction were greater than the GF along the vertical direction. Thus, the tendon-inspired conductive hydrogels with anisotropy could be used as flexible sensors for joint motion detection and voice recognition. The anisotropic hydrogel-based sensors are highly expected to promote the great development of emerging soft electronics and medical detection.