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Eggshells are the New Bio-piezoelectric Materials- A Source of Green Energy

With the advent of new technological developments, the energy deficient world is progressing towards greener source of energy that is cost effective, sustainable, and aims at meeting the rising energy demands of the contemporary mankind. Bio-inspired piezoelectric materials are the most biocompatible and non-toxic materials that have found use in green energy generation, which is pollution free as well.

Very few researches have focused on studying the wider aspects of bio-piezoelectric materials, which is due to its lower energy conversion rate and low piezoelectric coefficient. This has put out many physical hurdles in the path of developing bio-piezoelectric inducers with high energy efficiency and high power density. Even the developed bio-piezoelectric substances had some serious downsides, such as its low availability, toxicity, low biodegradability, and low biocompatibility. A novel approach has been adopted by the Indian Institute of Technology (IIT), Kharagpur. It is for the first time that it has been able to generate electrical energy from various sources; mechanical, acoustic, and wind, has been made. It is efficient to convert energy to about 62%. This high voltage of the nanogenerator can be put to use and light up about 100 commercial microwatt LEDs.

Having used the proteins found in eggshells for developing small devices which can cultivate electricity. The researchers claimed of the proteins that are found in the eggshell’s membranes contain properties of piezoelectric, which under any mechanical pressure generate electricity. Professor Bhanu Bhusan Khatua from IIT Kharagpur stated that bio-based green energy still remains to be explored effectively so as to meets the demands of energy of human beings.

Professor Khatua who led the research that has been published in the ‘Materials Today Energy’ journal said that the bio-piezoelectric that were reported had multiple drawbacks, as they were unavailable, toxic, non-biodegradable, non-biocompatible, did not favour the industries and had fabrication steps which were complex in nature. He also added about the uniqueness that their work carries, is the direct utilization of natural and organic membrane of the shell as an appropriate piezoelectrical material, that are dumped in a huge scale in our daily garbage lump. And this simple and natural innovation approaches a definite provision of benefits to the forthcoming science energy, specifically in vivo biomedical applications.

The researchers stated that the device may have a possibility to be able to replace all the conventional methods to power the medical devices in the near future. Researches, inclusive of those from Pohang University of Science and Technology in South Korea, separated the soft membrane that is present in the eggshell, in order to build the device. They coated the membrane with thin tapes of copper on both the sides, and attached gold electrodes to them, finally encapsulating the arrangement in silicon-based organic polymer.

The five assorted devices by the researchers portrayed the amount of voltage required to light-up almost 90 LEDs in green. These findings show hoe advanced and effective it can be if commercialized. Turns out, the device responds very sensitively towards a minute pressure that arises from the pulse, body movements when at rest and walking conditions and water drop, that suggests that they can be used to impart power to various applications inclusive of health measure apps, sensors, and fitness trackers.

As said by the researchers, this work would significantly play a role in uplifting the green energy technology of harvesting as self-powered and easily implantable as well as wearable electronics. The team earlier created a device similar to this by using the skins of onions. To which Professor Khatua said that the particular work based on onion skins piezoelectric nanogenerator laid emphasis on utilizing materials based on cellulose for energy harvesting applications. He also mentioned about their trials of exploring other bio-materials, like nanofibers based on cellulose, organic silk, etc., which may contain higher piezoelectric coefficient and output performances for wider areas of application, inclusive of health-care strategies. Efficient and effective harvesting of these bio-mechanical energies can prove to be sources of a substitute to green energy to impart power to varied daily used electronic devices that are portable in nature and can be a replacement of batteries as traditional supply of power in the future.

Co-author of the paper Sandeep Maiti says that the device was found to be very sensitive that even a small force from outside like touching and flow of hair could tamper it. It even was highly mechanically durable, and zero change in the output was observed for nearly 1,80,000 cycles, and was chemically stable for about 10 weeks, which made it appropriate to applied on various monitoring purposes.

The device was able to transform the energy from biomechanical to electrical, on placing it as a thin film on the wrist. Similarly, it was placed on the throat of a person who spoke, gargled or swallowed. On being pressed by the heel, it generated almost 58 volts, and on being placed under a running car it generated 79 volts. It was capable of converting the pressure put on by water falling from a tap into electricity. The device produced sound energy on being placed on a pair of speakers, and on being placed on the lid of a table fan, it transformed the wind pressure into electricity. Professor Khatua said that they want to use it for transforming heartbeat to impart power to a pace maker with the use of a rechargeable battery. And that they are trying to explore by applying this device on a dance floor, high throughput passages, and storing the electrical energy inside capacitors for running small devices.

These bio-piezoelectric materials are taken into account as excellent source of harvesting energy, as they have a nature of bio-compatibility and non-toxicity, as the researchers sound optimistic and are dedicatedly working to generate power that can serve in many ways.

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