Scientists are transforming fish "biowaste" into renewable energy source. A team of researchers at Jadavpur University in Koltata, India started recycling fish byproducts into piezoelectric energy harvesters.

In a study published in Applied Physics Letters, the scientists' concept was to create a bio-piezoelectric nanogenerator or "energy harvester" out of fish scales. According to the researchers, fish scales contain collagen fibers that have a piezoelectric property, meaning they can generate an electric charge in response to mechanical pressure.

"We wanted to explore what happens to the piezoelectric yield when a bunch of collagen nanofibrils are hierarchically well aligned and self-assembled in the fish scales," Dipankar Mandal, assistant professor at the Organic Nano-Piezoelectric Device Laboratory at the Jadavpur University's Department of Physics, said in a statement.

"And we discovered that the piezoelectricity of the fish scale collagen is quite large (~5 pC/N), which we were able to confirm via direct measurement."

The researchers used a demineralization process to make raw fish scales transparent and flexible, and then attached electrodes on both sides of a scale before laminating it. The result is a bio-piezoelectric generator that can harvest energy from movements around it.

According to the researchers, the nanogenerators are capable of harvesting several types of mechanical energies, including body movements, wind flow and even vibrations. Repeatedly touching the nanogenerator with a finger could even turn on more than 50 blue LEDs, the scientists said.

Apart from portable electronics, the work could also be used in transparent electronics, biocompatible and biodegradable electronics, and edible electronics. It could also be used in self-powered implantable medical devices, surgeries and targeted drug delivery.

"In the future, our goal is to implant a bio-piezoelectric nanogenerator into a heart for pacemaker devices, where it will continuously generate power from heartbeats for the device's operation," Mandal said. "Then it will degrade when no longer needed. Since heart tissue is also composed of collagen, our bio-piezoelectric nanogenerator is expected to be very compatible with the heart."

The U.S. generates about 140 trillion calories of food waste in one year alone. But scientists are thinking of various ways to put inedible byproducts -- such as fish scales -- to good use. In South Africa, a 16-year-old schoolgirl invented a super-absorbent polymer made of orange peel to help fight drought in the region.

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