Protein in tears, egg whites may help generate electricity

A protein – found in egg whites, as well as tears, saliva and milk of mammals – can be used to generate electricity and power novel medical devices in the future, scientists say.

Researchers from the University of Limerick (UL) in Ireland observed that crystals of lysozyme, a model protein can generate electricity when pressed.

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 a 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.

“While piezoelectricity is used all around us, the capacity to generate electricity from this particular protein had not been explored,” said Aimee Stapleton from UL.

“The extent of the piezoelectricity in lysozyme crystals is significant. It is of the same order of magnitude found in quartz,” said Stapleton, lead author of the study published in the journal Applied Physics Letters.

“However, because it is a biological material, it is non toxic so could have many innovative applications such as electroactive, anti-microbial coatings for medical implants,” she said.

Crystals of lysozyme are easy to make from natural sources, researchers said.

The discovery may have wide reaching applications and could lead to further research in the area of energy harvesting and flexible electronics for biomedical devices.

Future applications of the discovery may include controlling the release of drugs in the body by using lysozyme as a physiologically mediated pump that scavenges energy from its surroundings.

Being naturally biocompatible and piezoelectric, lysozyme may present an alternative to conventional piezoelectric energy harvesters, many of which contain toxic elements such as lead.