Fish scales extracted from food waste have been used to build tiny generators that can convert mechanical energy, such as a touch or sound vibrations, to electrical energy. The work was done by physicists in India, who say that the piezoelectric device could be used to develop environmentally friendly, self-powered electronics with a wide-range of applications. Piezoelectric materials respond to mechanical stress by separating positive and negative electrical charge, and therefore can be used to convert the mechanical energy of vibrations into electrical energy.
Energy harvesting performance of an efficient flexible bio-piezoelectric nanogenerator (BPNG) is demonstrated, where “bio-waste” transparent fish scale (FSC), composed of self-assembled and ordered collagen nano-fibrils, serves as a self-poled piezoelectric active component, exhibiting intrinsic piezoelectric strength of −−5.0 pC/N. The dipolar orientation (∼19%) of the self-polarized FSC collagen is confirmed by the angular dependent near edge X-ray absorption fine structure spectroscopy. The BPNG is able to scavenge several types of ambient mechanical energies such as body movements, machine and sound vibrations, and wind flow which are abundant in living environment. Furthermore, as a power source, it generates the output voltage of 4 V, the short circuit current of 1.5 μA, and the maximum output power density of 1.14 μW/cm2 under repeated compressive normal stress of 0.17 MPa. In addition, serially integrated four BPNGs are able to produce enhanced output voltage of 14 V that turn on more than 50 blue light emitting diodes instantly, proving its essentially as a sustainable green power source for next generation self-powered implantable medical devices as well as for personal portable electronics with reduced e-waste elements.