Pressure produces electricity in crystals of enzyme found in tears and egg whites
Scientists from the MOSAIC research group at the Bernal Institute, University of Limerick (UL), Ireland found that crystals of lysozyme, a model protein that is abundant in egg whites of birds, and in tears, saliva and milk of mammals can generate electricity when pressed. Their report appears in the journal Applied Physics Letters (https://doi.org/10.1063/1.4997446).
The ability to generate electricity by applying pressure, known as direct piezoelectricity, is a property of materials such as quartz that can convert mechanical energy into electrical energy and vice versa. Such materials are used in variety of applications ranging from resonators and vibrators in mobile phones to deep ocean sonars to ultrasound imaging. Bone, tendon, and wood are long known to possess piezoelectricity.
‘The magnitude of the piezoelectricity in lysozyme crystals is appreciable’ says Aimee Stapleton, the lead author and an Irish Research Council EMBARK Postgraduate Fellow in the Department of Physics and Bernal Institute of UL. ‘It is of the same order of magnitude that can be found in collagen. This can lead to many innovative applications such as electroactive, anti-microbial coatings as lysozyme is known for its activity against bacteria’, she adds.
Crystals of lysozyme are easy to make from natural sources. ‘High precision structure of lysozyme crystals have been known since 1965’ says structural biologist and co-author Professor Tewfik Soulimane of the Department of Chemical Sciences and Bernal Institute. ‘In fact, it is the second protein structure and the first enzyme structure that was ever solved but’, he adds, ‘we are the first one to use these crystals to show the evidence of piezoelectricity’.
‘Crystals are the gold-standard for measuring piezoelectricity in non-biological materials. We showed that the same approach can be taken in understanding this effect in biology’ explains the team leader Professor Tofail Syed of the Department of Physics and Bernal Institute of UL. ‘This is a new approach as scientists so far have tried to understand piezoelectricity in biology using complex hierarchical structures such as tissues, cells or polypeptides rather than investigating simpler fundamental building blocks.’ He adds.
Further information on the report can be found from the article: “The Direct Piezoelectric Effect in the Globular Protein Lysozyme,” by Aimee Stapleton, Mohamed R. Noor, John Sweeney, Vincent Casey,
Andrei Kholkin, Christophe Silien, Abbasi A. Gandhi, Tewfik Soulimane and Syed A. M. Tofail, Applied Physics Letters (2017). The article can be accessed at https://doi.org/10.1063/1.4997446.
Dr Lisa O’Donoghue, a Materials Scientist at the University of Limerick, has developed a process to automate the removal of hazardous materials from TVs during recycling.
The WEEE and ROHS Directives, which all EU member states are required to implement, stipulate that components containing mercury and liquid crystals must be removed from LCDs.
The recycling of Liquid Crystal Display (LCD) panels is posing a particular problem for WEEE recyclers in the EU. The majority of recyclers use a manual disassembly process to remove the mercury lighting tubes and LCD panel which is a slow and labour intensive process. The difficulty of LCD disassembly combined with high costs has led to a situation of stockpiling of LCDs at recycling facilities across Europe.
The WEEE recycling industry is in urgent need of an efficient and low cost LCD recycling process to help them comply with the WEEE Directive. Click here to read Dr Lisa Donoghue’s recent interview with Silicon Republic on LCD recycling.
Dr. O’Donoghue coordinated a €1.6 million EC funded project called ReVolv with 6 partners to launch the technology at TRL 9 this year. Further information can be found at www.revolvproject.eu
MOSAIC Researchers squeeze low-cost electricity from biomaterial
Mobile phone speakers and motion detectors in cars and video games may soon be powered by electricity generated from low cost and sustainable biomaterials. MOSAIC researchers at the 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 and SFI-funded post-graduate researcher at the Department of Physics and the Bernal Institute, UL, Sarah Guerin.
“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 patent pending 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.