Nanoengineered\nInk for Designing 3D Printable Flexible\nBioelectronics

Abstract

Flexible electronics require elastomeric\nand conductive biointerfaces\nwith native tissue-like mechanical properties. The conventional approaches\nto engineer such a biointerface often utilize conductive nanomaterials\nin combination with polymeric hydrogels that are cross-linked using\ntoxic photoinitiators. Moreover, these systems frequently demonstrate\n poor biocompatibility and face trade-offs between conductivity and\nmechanical stiffness under physiological conditions. To address these\nchallenges, we developed a class of shear-thinning hydrogels as biomaterial\ninks for 3D printing flexible bioelectronics. These hydrogels are\nengineered through a facile vacancy-driven gelation of MoS₂ nanoassemblies with naturally derived polymer-thiolated gelatin.\nDue to shear-thinning properties, these nanoengineered hydrogels can\nbe printed into complex shapes that can respond to mechanical deformation.\nThe chemically cross-linked nanoengineered hydrogels demonstrate a\n20-fold rise in compressive moduli and can withstand up to 80% strain\nwithout permanent deformation, meeting human anatomical flexibility.\nThe nanoengineered network exhibits high conductivity, compressive\nmodulus, pseudocapacitance, and biocompatibility. The 3D-printed cross-linked\nstructure demonstrates excellent strain sensitivity and can be used\nas wearable electronics to detect various motion dynamics. Overall,\nthe results suggest that these nanoengineered hydrogels offer improved\nmechanical, electronic, and biological characteristics for various\nemerging biomedical applications including 3D-printed flexible biosensors,\nactuators, optoelectronics, and therapeutic delivery devices.