Has anyone heard of sound harvesting?
I think you’ll be hearing a lot about this in the future
Nanotechnologist Tahir Cagin, a professor at of Chemical Engineering at Texas A&M University published an article with his colleagues this fall in “Physical Review B,” the scientific journal of the American Physical Society. It deals with a breakthrough he made that could lead to cell phones with no conventional batteries; powering themselves using energy harvested from sound. No more plugging in your phone to charge it overnight, it gets charged by using it. Could this be a real possibility or is it just a ploy to make us go over our cell minutes?
I can see it now…”Hello Jay, How’s it hanging?….No, nothing’s new, I’m just calling cause my phone needs charging…”
As far as I can tell, this does seem plausible (the breakthrough, not the ploy)
Cagin’s breakthrough involves a very cool class of materials called piezoelectrics. Piezoelectrics (usually crystals and ceramics) generate an electric potential when they experience mechanical stress like stretching, bending or twisting. This happens because the stress in the material separates the charge across the material’s width which sets up a voltage that can be put to use. I’m not sure how this occurs at an atomic level. If anyone knows, please let me know. Conversely, piezoelectrics also change their physical properties in the presence of an electric field.
This phenomenon isn’t new, it was discovered in the 1880s by French scientists. They were used first in sonar during World War 1. Today you can find them in quartz watches, microphones, and car cigarette lighters. Do they even make those anymore?
There’s even a night club in Europe that has piezoelectrics under the dance floor that are used for power generation from people walking and dancing.
One problem with these materials is that they’ve been impractical. They produce a nice amount of voltage or pure electric charge, but not much current which is the directed charge that powered devices depend on.
What Cagin discovered is a specific performance sweet spot for a piezoelectric ceramic.
As Cagin says: “We have demonstrated that when you go to a particular length scale – between 20 and 23 nanometers – you actually improve the energy-harvesting capacity by 100 percent.”
A nanometer is a billionth of a meter
To give some perspective…The basketball player Shaquille O’Neal, is 2,160,000,000 nanometers tall.
I hope that helps
Presumably, the idea would then be that you’d have thousands of these tiny buggers in your cell phone, harvesting energy from sound you make or perhaps even ambient sound. This energy would then be transferred to the cell-phone’s battery to run the device.
Other applications could include harvesting the energy of tiny pressure changes or miniscule body movements to power laptops or even drug delivery devices and sensors that are in our bodies.
One of the take homes from this that I feel strongly about is that this is a great example of how little we really know about the nano-scale. We’ve learned much in the last few decades but it is still primarily an undiscovered country. We’re not at the point where we could have predicted that at 21 nanometers this material would double its efficiency. That’s why basic science research is so important. Basic research in nanotechnology is especially important because the nano realm is so unknown and offers so much potential (so to speak :-)).