Published on August 31st, 2011 | by Nicholas Brown1
Batteries that Charge Themselves with Mechanical Energy
MicroGen Systems has been working on electricity-generating chips designed to power wireless sensors like those used to monitor tire pressure and environmental conditions.
These chips convert the mechanical energy of vibrations into electricity, which is then used to charge a small battery, which in turn powers the sensors.
If the chips are capable of generating adequate electrical energy, then they could mostly (or maybe even completely) eliminate the need to replace the batteries.
The core of MicroGen’s chips is a 1 cm2 array of silicon cantilevers that oscillate when the chip is jostled. At the base of the cantilevers is a bit of piezoelectric material: when it’s strained by vibrations, it produces a voltage that can be used to generate electrical current. Voltage is what causes current to flow.
The array of cantilevers is mounted on top of a postage-stamp-sized, thin-film battery that it charges. The current passes from the piezoelectric array through an electrical device that converts the current to an appropriate DC current that is suitable for charging the battery. When the chip is shaken by the vibrations of a rotating tire, for example, it can produce about 200 microwatts of power.
An efficient vibration-energy-harvesting device has the potential to be very beneficial because there are so many vibrating devices, such as mechanical machines, in general, including automobiles, generators, engines in general, and fans, as well as humans walking, arm and hand movements, and much more.
David Culler, chair of computer science at the University of California, Berkeley said: ”If you can get it down to a small size, 200 microwatts is potentially quite useful.”
Robert Andosca, the founder and president of MicroGen Systems, said that what sets this technology apart from other piezoelectric generators is the fact that it is made of a non-toxic material known as PZT.
200 microwatts of power might not be much, but if it is small enough, it could be very beneficial to tiny sensors that need to be integrated into small places.