Tears are turning up in the scientific world in some fairly unusual ways recently. Apart from this strange device that can turn them into ammunition for a peculiar weapon, they can – according to a new study – also be squashed in order to generate electricity.
Writing in the journal Applied Physics Letters, a team from the University of Limerick (UL) found out that lysozyme, a protein that is found in mammalian tears, milk, and saliva, as well as the egg whites of birds, can give off a spark when compressed. This is thanks to something known as the piezoelectric effect, which explains how certain materials, including quartz and diamonds, can convert mechanical energy into something that would power your smartphone.
“While piezoelectricity is used all around us, the capacity to generate electricity from this particular protein had not been explored,” lead author Aimee Stapleton, a physicist and postgraduate fellow at UL, said in a statement.
Piezoelectricity means “pressure amber”, the latter term of which derives from the Ancient Greek word for a mystical source of electrical charge. The principle underlying it has been known about since the mid-18th Century, and today it is used to make advanced sensors, motors, clocks, and power sources.
Thanks to the fact that piezoelectric materials can also be used to convert electrical energy into mechanical energy, the field of piezosurgery exists: Small currents of certain frequencies can be used to trigger incredibly precise vibrations in incision tools that can be used in minimally invasive medical procedures.
This new research reminds us that not all piezoelectric materials are non-organic. Biological matter, including bone, DNA strands, and even various individual proteins, have these magical-sounding characteristics too – including, as it happens, one found in tears.
Until this point, this particular protein had not really been suspected of exhibiting this effect, but the innovative UL researchers simply couldn’t resist trying out something that is found in such abundance. Turns out that their hunch was right – and now, they’ve made a name for themselves as pioneers of biological piezoelectricity, much of which has long been enigmatic.
As it so happens, the effect found in lysozyme crystals is of a similar magnitude to that of the commonly used quartz. “However, because it is a biological material, it is non-toxic,” Stapleton added, “so it could have many innovative applications such as electroactive anti-microbial coatings for medical implants.”
Don’t expect any major innovations to make appearances at home anytime soon, though. Although we’re sure we’d all enjoy having a pouch we could cry into and then jump up and down on to electrify our laptops, this paper sadly represents the beginning of all things tear-powered.
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