Melt-Compounded Keratin-TPU Self-Assembled Composite Film as Bioinspired e-Skin

Abstract

Inspired by the keratin-elastin composition of human skin, here an artificial skin (alias electronic (e)-skin) is developed through solvent-free extrusion based melt mixing of thermoplastic polyurethane (TPU) with the biowaste human hair keratin. Self-assembled composite film of TPU and keratin (i.e., PUK) shows leg skin equivalent coefficient of friction value of 0.26 +/- 0.05, cheek skin equivalent average surface roughness (Ra) of 0.047 +/- 0.07 mu m, cytoskeletal keratin intermediate filament network like rheological behavior, porous morphology, and skin like positive triboelectric property, when the keratin content is 10 wt%. H-bonded self-assembled network and lubricating behavior of cysteine-rich keratin provide such tribological and rheological behaviors of the PUK. Single electrode triboelectric nanogenerator (STENG) made of PUK containing 10 wt% keratin (i.e., 10% PUK) not only shows clear discrimination between the touch feeling sensations of bare, and glove protected human finger, by producing output voltage of approximate to 1 and approximate to 16 V cm(-2), respectively, but it also can discriminate the tactile sensations of different objects viz., aluminum foil, cotton glove, wood, polyimide, and poly(tetrafluoroethylene) by producing different output voltages, resembling that the PUK composite film is well fitted for e-skin applications.