A Tough and Self-Powered Hydrogel for Artificial Skin

Hydrogels, because of their water-rich nature and soft mechanical characteristics that resemble those of skin tissues, are promising materials for artificial skin. Existing piezoresistive hydrogels combine unique tissue-like and sensory properties, but these materials are often plagued by problems such as poor mechanical properties and the requirement of an external power supply or batteries. Here, a tough and self-powered hydrogel based on a tough polyacrylonitrile hydrogel incorporating ferroelectric poly(vinylidene fluoride) (PAN-PVDF) is reported. The dipolar interactions between the PVDF and PAN chains cause an increase in the best electroactive beta-phase PVDF percentage in the composites from 0 to 91.3%; thus, a maximum piezoelectric coefficient d(33), 30 pC was achieved for the hydrogels. Skin-like Young's modulus values (1.33-4.24 MPa), stretchability (90-175%), and high toughness (1.23 MJ/m(2)) were achieved simultaneously for the hydrogels. This tough gel is capable of generating an electrical signal output (approximate to 30 mV and approximate to 2.8 mu A) with a rapid response (approximate to 31 ms) due to the stress -induced poling effect. Moreover, the gel can also precisely detect physiological signals (e.g., gesture, pulse, and words). This study provides a simple and efficient method for artificial skin with high toughness, self-power generation capability, fast response, low cost, and tissue-like properties.