IIT scientists use eggshells to generate electricity

Scientists from Indian Institute of Technology (IIT) Kharagpur have used eggshell proteins to develop tiny devices that can harvest electricity from body movements, and could power wearable sensors and devices in future.

Proteins found in eggshell membranes have piezoelectric properties, that is, under mechanical stress they produce electricity, researchers said.

Bio-inspired piezoelectric materials are considered to be an excellent energy harvesting source since they are non-toxic and biocompatible.

They also have the ability to generate significant power without contributing to environmental pollution.

"However, bio-based green energy is still effectively not explored to fulfil the energy demand of contemporary human mankind," Bhanu Bhusan Khatua, a professor at IIT Kharagpur in West Bengal, told PTI over the telephone.

"Reported bio-piezoelectric have serious drawbacks, such as availability, toxicity, non-biodegradable, non-biocompatibility, industrially unfavourable as well as complex fabrication steps, which limit its potential applications in real life," said Khatua, who led the research published in the journal Materials Today Energy.

"The uniqueness of our work lies in the novelty of utilising nature driven eggshell membrane directly as efficient piezoelectric material, which are discarded in large scale in our everyday life," he said.

"This simple innovative homespun approach definitely would provide a huge benefit to future energy science, especially in-vivo biomedical applications," he added.

The device may be able to replace conventional ways of powering medical devices in the future, researchers said.

To build the device, researchers including those from Pohang University of Science and Technology in South Korea, isolated the soft membrane present inside the eggshell.

The membrane was coated on both sides with thin copper tapes, and gold electrodes were attached to them. The arrangement was encapsulated in a silicon-based organic polymer.

Researchers showed that assembling five of these devices provides enough voltage to light-up over 90 green LEDs. The findings suggest that the advance can be effectively commercialised.

The device is ultrasensitive towards very minute pressure arising from the pulse, body motions at rest and walking conditions and water drop, suggesting that it could be used to power numerous applications including fitness trackers, health monitors and sensors.

The work would have a significant role towards up-lifting the green energy harvesting technology as self-powered implantable and wearable electronics, researchers said.

The team has previously created a similar device using onion skins.

"Our previous work on onion-skin based piezoelectric nanogenerator focused on utilisation of cellulose-based materials for energy harvesting applications," Khatua said.

"We are trying to explore other bio-materials, such as natural silk, cellulose-based nanofibres etc, which may have higher piezoelectric coefficient and output performances for wide application areas, including health-care monitoring," he added.

Effective harvesting of such kinds of bio-mechanical energies can be sources of alternative green energy to power up various daily used portable electronics that can replace batteries as traditional power supplier in near future, researchers said.