Energy Harvesting Using Liquid Metals

Mechanical energy is readily available. Examples include vibrations from engines, motion from body movement, wind, and oceans. We sought to convert such motion into electricity. The device consists of a low toxicity liquid metal (gallium) embedded in hydrogel. Hydrogel is a biocompatible, water-swollen polymer (similar to contact lenses or Jello). Metals that contact water naturally generate an electrical double layer. This is the basis for so-called supercapacitors. By using entirely soft materials, the device increases its metal-gel interfacial area during deformation. This increase in area also increases the capacitance, which can drive charge (electricity) through a circuit. Consequently, it converts mechanical motion into electricity.