Bioinspired Flexible Hydrogelation with Programmable Properties for Tactile Sensing

YX Wang and Q Geng and H Lyu and WXP Sun and XY Fan and K Ma and K Wu and JH Wang and YC Wang and DQ Mei and CC Guo and P Xiu and DY Pan and K Tao, ADVANCED MATERIALS, 36 (2024).

DOI: 10.1002/adma.202401678

Tactile sensing requires integrated detection platforms with distributed and highly sensitive haptic sensing capabilities along with biocompatibility, aiming to replicate the physiological functions of the human skin and empower industrial robotic and prosthetic wearers to detect tactile information. In this regard, short peptide-based self- assembled hydrogels show promising potential to act as bioinspired supramolecular substrates for developing tactile sensors showing biocompatibility and biodegradability. However, the intrinsic difficulty to modulate the mechanical properties severely restricts their extensive employment. Herein, by controlling the self-assembly of 9-fluorenylmethoxycarbonyl-modifid diphenylalanine (Fmoc-FF) through introduction of polyethylene glycol diacrylate (PEGDA), wider nanoribbons are achieved by untwisting from well-established thinner nanofibers, and the mechanical properties of the supramolecular hydrogels can be enhanced 10-fold, supplying bioinspired supramolecular encapsulating substrate for tactile sensing. Furthermore, by doping with poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and 9-fluorenylmethoxycarbonyl-modifid 3,4-dihydroxy-l-phenylalanine (Fmoc- DOPA), the Fmoc-FF self-assembled hydrogels can be engineered to be conductive and adhesive, providing bioinspired sensing units and adhesive layer for tactile sensing applications. Therefore, the integration of these modules results in peptide hydrogelation-based tactile sensors, showing high sensitivity and sustainable responses with intrinsic biocompatibility and biodegradability. The findings establish the feasibility of developing programmable peptide self-assembly with adjustable features for tactile sensing applications. By modulating Fmoc-FF self-assembled architectures and improving their conductivity and adhesion, bioinspired supramolecular hydrogels of flexible mechanical rigidity, high conductivity, or high adhesion are achieved, respectively, which can be employed as an encapsulation layer, sensing unit, and adhesive layer for engineering tactile sensors. The findings establish the feasibility of developing peptide programmable hydrogelation of modulatable features for tactile sensing applications. image

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