Mobile phone speakers and motion detectors in cars and video games may soon be powered by electricity generated from low cost and sustainable biomaterials, according to research carried out at University of Limerick (UL), Ireland.
Scientists at UL’s Bernal Institute have discovered that the biomolecule glycine, when tapped or squeezed, can generate enough electricity to power electrical devices in an economically viable and environmentally sustainable way. The research was published on December 4, 2017 in leading international journal Nature Materials.
Glycine is the simplest amino acid. It occurs in practically all agro and forestry residues. It can be produced at less than one per cent of the cost of currently used piezoelectric materials.
Piezoelectric materials generate electricity in response to pressure, and vice versa. They are widely used in cars, phones, and remote controls for games consoles. Unlike glycine, these materials are normally synthetic and often contain toxic elements such as lead or lithium.”It is really exciting that such a tiny molecule can generate so much electricity,” said lead author Sarah Guerin, a post-graduate student at the Department of Physics and the Bernal Institute, UL.
“We used computer models to predict the electrical response of a wide range of crystals and the glycine number was off the charts. We then grew long, narrow crystals of glycine in alcohol,” she added, “and we produced electricity just by tapping them.”
Sarah’s PhD supervisor Dr Damien Thompson, adds, “The predictive models we are developing can save years of trial-and-error lab work. The modelling data tells us what kinds of crystals to grow and where best to cut and press those crystals to generate electricity.”
Co-author and Science Foundation Ireland (SFI) Centre for Medical Devices (CURAM) investigator Professor Tofail Syed said: “We also have a pending patent that translates our findings to applications such as biodegradable power generation, devices detecting diseases inside of the body and physiologically controlled drug pumps”.
Previously, Bernal scientists discovered piezoelectricity in the globular protein lysozyme, found in tears, egg-white and saliva, and hydroxyapatite, a component of bone.
“The current finding extends the technology towards pragmatic, low-cost, renewable sources for electricity generation,” according to Professor Luuk van der Wielen, Director of the Bernal Institute and Bernal Professor of Biosystems Engineering and Design. “The finding translates the earlier Bernal scientists’ world-leading contribution in bio-piezoelectricity towards a large-scale and affordable application potential.”
Professor Edmond Magner, Dean of Science and Engineering at UL, said: “UL’s Department of Physics and Bernal Institute researchers continue to pioneer the use of biological crystals for electrical applications. This work places them at the forefront in the development of bio-piezoelectric devices”.
The full paper, Control of Piezoelectricity in Amino Acids by Supramolecular Packing, by Sarah Guerin, Aimee Stapleton, Drahomir Chovan, Rabah Mouras, Matthew Gleeson, Cian McKeown, Mohamed R Noor, Christophe Silien, Fernando M F Rhen, Andrei L Kholkin, Ning Liu, Tewfik Soulimane, Syed A M Tofail, and Damien Thompson, is published in Nature Materials, December 4, 2017. Link: https://www.nature.com/articles/nmat5045
Control of piezoelectricity in amino acids by supramolecular packing
Piezoelectricity, the linear relationship between stress and induced electrical charge, has attracted recent interest due to its manifestation in biological molecules such as synthetic polypeptides or amino acid crystals, including gamma (γ) glycine. It has also been demonstrated in bone, collagen, elastin and the synthetic bone mineral hydroxyapatite. Piezoelectric coefficients exhibited by these biological materials are generally low, typically in the range of 0.1–10 pm V−1, limiting technological applications. Guided by quantum mechanical calculations we have measured a high shear piezoelectricity (178 pm V−1) in the amino acid crystal beta (β) glycine, which is of similar magnitude to barium titanate or lead zirconate titanate. Our calculations show that the high piezoelectric coefficients originate from an efficient packing of the molecules along certain crystallographic planes and directions. The highest predicted piezoelectric voltage constant for β-glycine crystals is 8 V mN−1, which is an order of magnitude larger than the voltage generated by any currently used ceramic or polymer.
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University of Limerick
This publication has emanated from research conducted with the financial support of Science Foundation Ireland (SFI), and is co-funded under the European Regional Development Fund under Grant Number 13/RC/2073.
About Sarah Guerin:
Sarah Guerin, from Tralee, County Kerry, Ireland, is a final year PhD student at the University of Limerick. Her research uses a combination of quantum mechanical calculations and advanced characterisation techniques to develop the next generation of single crystal piezoelectric technologies. In August 2015 she graduated with a first class honours degree in Applied Physics. She completed her undergraduate internship at Analog Devices International, going on to complete her undergraduate thesis with the company.