Scientists harvest electricity from tears

Oct. 2 (UPI) -- Sad about the battery drain on your new smartphone? A good cry might help. Scientists have found a way to harvest electricity from tears.

In recent lab experiments, researcher at the University of Limerick's Bernal Institute, in Ireland, found lysozyme crystals yield an electric current when pressurized. Lysozyme is found in tears and saliva, as well as the whites of bird eggs and the milk of mammals.

Quartz also possesses the ability to generate electricity when pressurized -- a quality known as piezoelectricity. The ability makes quartz useful for a variety technologies. The material is often used to make resonators inside mobile phones, ultrasound devices and other types of sensors.

"While piezoelectricity is used all around us, the capacity to generate electricity from this particular protein had not been explored," Aimee Stapleton, a physicist at the Bernal Institute, said in a news release. "The extent of the piezoelectricity in lysozyme crystals is significant. It is of the same order of magnitude found in quartz. 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."

The precise structure of lysozyme crystals was the first enzyme structure and protein structure discovered and described by scientists. It was been frequently studied, and yet, the latest research is the first to describe the crystals' piezoelectricity.

"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," said Tofail Syed, a physics professor at at the University of Limerick. "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."

Scientists believe their research -- detailed this week in the journal Applied Physics Letters -- could be used to design biocompatible piezoelectric energy harvesters for biomedical devices. Many conventional harvesters contain toxic elements like lead.

"The impact of this discovery in the field of biological piezoelectricity will be huge and Bernal scientists are leading from the front the progress in this field," said Luuk van der Wielen, director of Bernal Institute.