Electricity Generation through Light-Responsive Diving-Surfacing Locomotion of a Functionally Cooperating Smart Device.

Mini-generators converting other forms of energy into electric energy are ideal power supplies for widely used microelectronic devices because they need only a low power supply in the range of µW to mW. Among various creative strategies to fabricate mini-generators, recently developed functionally integrated systems combining self-propulsion of small objects and the application of Faraday's law show advantages such as facile, noncontact, low resistance, and durability. However, wide application of such functionally integrated systems is currently restricted by artificial energy inputs, such as chemical fuels or mechanical work, and harvesting energy available in the environment or nature is urgently required. Herein, a light-responsive functionally cooperating smart device is developed as a mini-generator that can directly harvest naturally available light energy for diving-surfacing motions, thus converting mechanical energy into electricity through Faraday's law. The mini-generator generates a maximum voltage of 1.72 V with an energy conversion efficiency of 2.44 × 10-3 % to power LEDs and shows a lifetime of at least 30 000 s. By using environmental energy, the study may promote the concept of a functionally cooperating system as an economic and facile power supply for microelectronics, reducing their dependence on batteries.