PUBLISHED: 17:42, 2 October 2017 | UPDATED: 18:52, 2 October 2017
A team of researchers has discovered that crying can generate electricity.
They discovered that applying pressure to a protein found in tears as well as egg whites can generate electricity.
The discovery could have wide reaching applications in the field of flexible electronics for biomedical devices - for example controlling the release of drugs in the body.
Dr Aimee Stapleton (pictured), Irish Research Council EMBARK Postgraduate fellow at University of Limerick, Ireland and lead author of research, says the new discovery could have innovative applications such as electroactive, anti-microbial coatings for medical implants
The study was conducted by researchers at the Bernal Institute at the University of Limerick (UL) in Ireland.
The researchers observed that crystals of lysozyme, a model protein that is abundant in egg whites of birds as well as in the tears, saliva and the milk of mammals, can generate electricity when pressed.
The ability to generate electricity by applying pressure, called piezoelectricity, is a property of materials such as quartz, which can convert mechanical energy into electrical energy, and vice versa.
Other materials that have this property include bone, tendon and wood.
These kinds of materials are used in a variety of applications ranging from resonators and vibrators in mobile phones to deep ocean sonars, as well as ultrasound imaging.
'While piezoelectricity is used all around us, the capacity to generate electricity from this particular protein had not been explored,' says Dr Aimee Stapleton, the lead author of the study and an Irish Research Council Postgraduate Fellow.
'The extent of the piezoelectricity in lysozyme crystals is significant.
'It is of the same order of magnitude found in quartz.
According to the researchers, crystals of lysozyme are easy to make from natural sources.
'The high precision structure of lysozyme crystals has been known since 1965,' said structural biologist at UL and co-author Dr Tewfik Soulimane.
Crystals of lysozyme, a model protein that is abundant in egg whites of birds as well as in the tears, saliva and the milk of mammals, can generate electricity when pressed. Pictured are optical microscopy images of (a) monoclinic and (b) tetragonal aggregate films of lysozyme
'In fact, it is the second protein structure and the first enzyme structure that was ever solved, but we are the first to use these crystals to show the evidence of piezoelectricity.'
According to the team leader of the research, Dr Tofail Syed at UL's Department of Physics, 'crystals are the gold standard for measuring piezoelectricity in non-biological materials.'
'Our team has shown that the same approach can be taken in understanding this effect in biology.
'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.'
The authors of the study (L to R) Dr John Sweeney, Dr Aimee Stapleton and Dr Vincent Casey of University of Limerick
According to the researchers, the discovery may have wide reaching applications and could lead to further research in energy harvesting and flexible electronics for biomedical devices.
For example, future applications of the discovery may include controlling the release of drugs in the body by using lyzozyme as a pump that scavenges energy from its surroundings.
Because lysozyme is biocompatible and piezoelectric, it may be an alternative to conventional piezoelectric energy harvesters, many of which contain toxic elements such as lead.
Future applications of the discovery may include controlling the release of drugs in the body by using lyzozyme as a pump that scavenges energy from its surroundings