Liquid metals are attractive materials for stretchable electronics owing to their high electrical conductivity and near-zero Young's modulus. However, the high surface tension of liquid metals makes it difficult to form films. A novel stretchable film is proposed based on an over-layered liquid-metal network. An intentionally oxidized interfacial layer helps to construct uninterrupted indium and gallium nanoclusters and produces additional electrical pathways between the two metal networks under mechanical deformation. The films exhibit gigantic negative piezoresistivity (G-NPR), which decreased the resistance up to 85% during the first 50% stretching. This G-NPR property is due to the rupture of the metal oxides, which allows the formation of liquid eutectic gallium-indium (EGaIn) and the connection of the over-layered networks to build new electrical paths. The electrodes exhibiting G-NPR are complementarily combined with conventional electrodes to amplify their performance or achieve some unique operations.
Keywords: liquid metal; negative piezoresistivity; over-layered networks; sequential deposition; stretchable electrodes; thin films.
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