Researchers in India are recycling fish scales into energy harvesters for self-powered electronics.
Large quantities of fish are consumed in India on a daily basis, which generates a huge amount of fish biowaste. The researchers from the Organic Nano-Piezoelectric Device Laboratory at Jadavpur University found that fish scales contain collagen fibres that have a piezoelectric property: an electric charge is generated in response to applying a mechanical stress.
They sought to harness this property to fabricate a bio-piezoelectric nanogenerator. They first collected hard, raw fish scales from a fish processing market, then used a demineralisation process to make them transparent and flexible, explained assistant professor Dipankar Mandal.
“We were able to make a bio-piezoelectric nanogenerator a.k.a. energy harvester with electrodes on both sides, and then laminated it,” Mandal said.
While it’s well known that a single collagen nanofiber exhibits piezoelectricity, until now no one had attempted to focus on hierarchically organising the collagen nanofibrils within the natural fish scales.
“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,” he added. “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 team’s work is the first known demonstration of the direct piezoelectric effect of fish scales from electricity generated by a bio-piezoelectric nanogenerator under mechanical stimuli without the need for any post-electrical poling treatments.
The resulting bio-piezoelectric nanogenerator can harvest several types of ambient mechanical energies, including body movements, machine and sound vibrations, and wind flow. Repeatedly touching the bio-piezoelectric nanogenerator with a finger can turn on more than 50 blue LEDs.
"We expect our work to greatly impact the field of self-powered flexible electronics,” Mandal said. “To date, despite several extraordinary efforts, no one else has been able to make a biodegradable energy harvester in a cost-effective, single-step process.”
The group’s work could potentially be for use in transparent electronics, biocompatible and biodegradable electronics, edible electronics, self-powered implantable medical devices, surgeries, e-healthcare monitoring, as well as in vitro and in vivo diagnostics.
One possible application is to implant the nanogenerator into a heart for pacemaker devices, where it will continuously generate power from heartbeats for the operation of the pacemaker. Such a nanogenerator would degrade when no longer needed. With heart tissue being composed of collagen, the bio-piezoelectric nanogenerator is expected to be very compatible with the heart.
[Image via VisualHunt]
Energy will be a major topic of discussion at the Australian Engineering Conference 2016 in Brisbane on November 23-25.