Search for: All records

Carbon chains immobilize water molecules, making a hydrogel elastic across temperatures 

We report a mechano-diffusion mechanism that harnesses mechanical deformation to control particle diffusion in stretchable hydrogels with a significantly enlarged tuning ratio and highly expanded tuning freedom. 

Abstract While in-situ underwater adhesives are highly desirable for marine exploration and underwater robotics, existing underwater adhesives suffer from significantly reduced performance compared to air-cured adhesives, mainly due to difficulties in removing interfacial water molecules. Here, we develop a pressure-sensitive in-situ underwater adhesive featuring superabsorbent particles infused with functional silane and hydrogel precursors. When injected into an underwater crack, the particles quickly absorb water, swell, and fill the crack. Mechanical pressure is applied to improve particle-particle and particle-substrate interactions, while heat is utilized to trigger thermal polymerization of the hydrogel precursors. This process creates porous adhesives via bulk polymerization and forms covalent bonding with the substrate via surface silanization. Our experiments demonstrate that mechanical pressure significantly enhances the adhesive’s stretchability (from 3 to 5), stiffness (from 37 kPa to 78 kPa), fracture toughness (from 1 kJ/m²to 7 kJ/m²), and interfacial toughness with glass substrates (from 45 J/m²to 270 J/m²). 

Soft bioelectronic devices exhibit motion-adaptive properties for neural interfaces to investigate complex neural circuits. Here, we develop a fabrication approach through the control of metamorphic polymers’ amorphous-crystalline transition to miniaturize and integrate multiple components into hydrogel bioelectronics. We attain an about 80% diameter reduction in chemically cross-linked polyvinyl alcohol hydrogel fibers in a fully hydrated state. This strategy allows regulation of hydrogel properties, including refractive index (1.37-1.40 at 480 nm), light transmission (>96%), stretchability (139-169%), bending stiffness (4.6 ± 1.4 N/m), and elastic modulus (2.8-9.3 MPa). To exploit the applications, we apply step-index hydrogel optical probes in the mouse ventral tegmental area, coupled with fiber photometry recordings and social behavioral assays. Additionally, we fabricate carbon nanotubes-PVA hydrogel microelectrodes by incorporating conductive nanomaterials in hydrogel for spontaneous neural activities recording. We enable simultaneous optogenetic stimulation and electrophysiological recordings of light-triggered neural activities in Channelrhodopsin-2 transgenic mice.