A team of scientists from the University of Limerick, in Ireland, has recently discovered a method for generating electricity from human saliva, milk, and tears. They now hope, of course, that this research could eventually lead to alternative ways to control release of drugs in the body. After all, the most conventional biomedical devices in use today feature energy harvesting methods that contain toxic elements like lead.
Basically, the team found that you can apply piezoelectricity to the protein lysozyme to generate electricity.
Lysozyme is a protein find naturally—and abundantly—in human tears, human saliva, and human milk; as well as the egg whites of birds. Piezoelectricity is the generating of electricity by applying pressure on this protein. You can actually use this method to produce electricity from materials like quartz, energy that you can then converted from mechanical energy into electrical energy. We already use piezoelectric materials in various applications including mobile phone vibrators, ocean sonar, and more.
According to lead study author Aime Stapleton, “While piezoelectricity is used all around us, the capacity to generate electricity from this particular protein had not been explored. The extent of the piezoelectricity in lysozyme crystals is significant.” The University of Limerick Bernal Institute Department of Physics Irish Research Council EMBARK Postgraduate Fellow goes on to say, “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.”
This is all good news, of course, but here is even better news: lysozyme crystals are easy to manufacture from natural sources. UL structural biologist, Professor Tewfik Soulimane adds, “The high precision structure of lysozyme crystals has been known since 1965. In fact, it is the second protein structure and the first enzyme structure that was ever solved,” he added, “but we are the first to use these crystals to show the evidence of piezoelectricity”.
Finally, UL Department of Phyiscs Professor, and lead author, Tofail Syed comments, “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.”