A gradient-distributed liquid-metal hydrogel capable of tunable actuation

• Although thermoresponsive hydrogels have numerous applications that range from soft robots, biomedical engineering, and actuators to sensors for artificial muscles, the existing hydrogel actuators undergo only unidirectional deformation under a single thermal stimulus and suffer from slow actuation and unstable interfacial adhesion in multiple layers. Herein, hydrogels containing gradient-distributed polydopamine-coated eutectic gallium-indium (PDA-EGaIn) nanodroplets in a poly(N-isopropylacrylamide) (PNIPAM) matrix and thus featuring a gradient distribution of thermal conductivity and an increased barrier towards water loss are shown to be capable of a rapid and tuneable thermoresponse. Notably, whereas hydrogels with a low content of PDAEGaIn undergo rapid one-way bending under a single thermal (45 degrees C) stimulus, those with a high content of PDAEGaIn undergo sequential bidirectional (bending) actuation. The ability of these hydrogels to undergo fast and tuneable actuation under a single thermal stimulus makes them suitable for use in grab-release instruments and soft robots.

Ämnesord

NATURVETENSKAP  -- Kemi -- Polymerkemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Polymer Chemistry (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Textil-, gummi- och polymermaterial (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Textile, Rubber and Polymeric Materials (hsv//eng)

Nyckelord

Thermoresponsive hydrogel

Liquid metal

Gallium

PNIPAM

Bidirectional actuation

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