Electricity from fish waste
doi:10.1038/nindia.2016.117 Published online 12 September 2016
Physicists at Jadavpur University (JU) in Kolkata report having fabricated tiny electric generators by exploiting the piezoelectric property of collagen fibres contained in fish scales, generally thrown away as waste1.
Piezoelectric devices generate electricity in response to mechanical stress. While it is well known that a single collagen fibre exhibits piezoelectricity, the JU researchers wanted to explore the electricity output from "a bunch of well aligned and self-assembled collagen fibres" in fish scales.
For this, they collected fish scales from a fish processing market and made them transparent and flexible for their experiments. They created flexible bio-piezoelectric nanogenerators (BPNG), where the fish scales, composed of self-assembled and ordered collagen nano-fibrils, served as a "self-poled piezoelectric active component". They showed that these nano-generators can produce electricity by harvesting energy from sound vibrations, wind flow and even repeated tapping with a finger.
Four such nano-generators linked together – by gently slapping with hands – could produce an output of 14 volts, sufficient to turn on 50 blue LEDs. The researchers hope their work will greatly impact the field of self-powered portable electronic devices, particularly medical devices such as a heart pacemaker, where they can continuously generate power from heartbeats.
1. Ghosh, S. K. & Mandal, D. Bio-piezoelectric nanogenerator made with fish scale. Appl. Phys. Lett. 109, 103701 (2016) doi: 10.1063/1.4961623