11 April 2014

Harvest free energy from the environment with polymer magic

Throughout history, hustlers, tricksters, and gamblers have become the craftiest mathematicians our world has ever seen. Among more tangible pursuits, little has turned more scientists into charlatans or more charlatans into scientists than the allure of harvesting free energy from the environment. The prospect of turning ambient vibration into the smooth flow of electrons is becoming closer to our grasp. A new piezoelectric design, based on stacked layers of PVDF polymer tuned to energy-absorbing and electron-dispensing perfection, has just been laid on the table by Singaporean scientists.

Polyvinylidene difluoride (PVDF) is a wonder material of sorts. While not quite as strong as nylon, it has revolutionized niche fishing by virtue of its comparative transparency, surface hardness, and tendency to sink. Its remarkable properties, including extreme pyroelectricity and piezoelectricity, have lent its use to everything from thermal camera sensors to electrodes for lithium batteries. In contrast to hard ceramic piezoelectrics, PVDF compresses instead of expands, or vice versa, when exposed to the electric fields.

Hard, brittle, and eminently fatigable ceramics are great for applications where high frequency, force, charge, or temperature capabilities are at a premium. The typical mechanical swag available to a smartphone, however, tends to be low and slow, yet with ample displacements. Diving-board style cantilevers and other force-focusing antenna are generally added, but they add significantly to the overall complexity.

PVDFPVDF has been employed previously in various incarnations of a mechanical harvester. Generally, it is used in combination with various metallization processes to add conductive layers or even provisions for energy storage. The innovation from Singapore was to optimize the number and thickness of the layers to create the lowest possible electrical impedance, while simultaneously minimizing the amount of aluminum coating which otherwise parasitically stiffens the whole works. Their models showed that a 22-layer structure could generate an energy output anywhere from five to 400 times higher than a single layer design of similar girth or heft.

Now, for any good power supply you want to have a low output impedance, at least relative to the load you have on it. That way, when your load changes, the current supplied will remain relatively constant over time. When the researchers got to testing an actual device, they found it performed in line with what their models had told them often a rare event. They hope to be able to turn the device into a replacement for batteries in small-scale electronics. But as we know, getting ahold of some power, keeping it handy for when you need, and then actually sourcing it can be very different problems.

a Extremetech article


Post a Comment

Get every new post delivered to your Inbox.


Copyright © 2018 Tracktec. All rights reserved.

Back to Top