Indian researchers recycle fish scales into energy nanogenerator

It’s a big step forward in self-powered flexible electronics.

Frank Rothe / Getty Images

Indians consume a lot of fish: Data from 2014 estimated that each urban citizen consumed an average of 2.8 kg per year, or about 3.7 million kg for the whole country. That leaves a lot of leftover bones, scales and tails. As they reported this week in Applied Physics Letters, a team of researchers at Jadavpur University looked for ways to re-use this "biowaste" and pioneered a method to generate electricity from it.

First, some biophysics. Fish scales have collagen fibers containing piezoelectric properties: Stress them and you generate a charge. Considering this, the researchers collected a large volume of them and used a demineralization process to make them transparent and flexible. Then they toyed with the hierarchical alignment of these treated scales, boosting their energy yield and effectively creating a bio-piezoelectric nanogenerator.

It can scavenge several types of ambient mechanical energies like body movements, machine and sound vibrations and wind flow. Even touching the nanogenerator produced enough electricity to light 50 LEDs. The result is a big step for self-powered flexible electronics, which could one day be developed into things like pacemakers energized by heartbeats that safely biodegrade in time. While it could also find applications in transparent and portable electronics, the biocompatibility likely makes this tech more valuable to medical uses like e-healthcare monitoring, in vitro diagnostics and edible devices.