Devices that use the wasted mechanical energy from clothing movements or even a heartbeat seem far out, if not just a bit creepy, but new advances in nanogenerators are making such energy-scavenging electronics possible.
Now researchers at Georgia Tech have made the first nanowire-based generators that can harvest sufficient mechanical energy to power small devices, including light-emitting diodes and a liquid-crystal display. [Technology Review]
The new generators use materials that have a particularly odd property: They collect a charge and drive a current when flexed (this is called piezoelectricity). The problem in using these materials for energy-harvesting applications has been that the materials that were sufficiently efficient at driving a current were too rigid, and those that were flexible enough weren’t very efficient.
Imagine a day in the future when you can charge your cell phone using your sneakers, or charge a touch-screen device merely by rolling up the flexible screen. New devices that take advantage of the piezoelectric effect–the tendency of some materials to generate an electrical potential when they’re mechanically stressed–are taking us one step closer to that reality.
Ville Kaajakari of the Louisiana Tech University harnessed this effect by developing a tiny generator that can be embedded in a shoe sole. The tiny smart device is part of “MEMS” or “micro electro mechanical systems,” which combine computer chips with micro-components to generate electricity [EarthTechling]. Each time the sneaker-wearer goes for a stroll, the compression action would power up the circuits in the generator and produce tiny bits of usable voltage. “This technology could benefit, for example, hikers that need emergency location devices or beacons,” said Kaajakari. “For more general use, you can use it to power portable devices without wasteful batteries” [Clean Technica].
For now, the amount of energy produced is very small, but the generator could theoretically be used to power sensors, GPS units or portable devices that don’t require a large amount of energy [Clean Technica]. The scientist hopes that the technology can be developed further to charge common devices like mobile phones.
Scientists have created the world’s smallest superconductor, made out of just four molecule-pairs and less than a nanometer wide. That’s far smaller than the head of a pin — which stretches across a million nanometers — and more on the order of a DNA molecule, which is about 2 nanometers wide [PopSci]. The invention, described in the journal Nature Nanotechnology, provides the first evidence that nanoscale molecular superconducting wires can be fabricated, which could be used for nanoscale electronic devices and energy applications [Xinhua]. Superconductive materials allow electrical currents to pass through with zero resistance, making them potentially useful to a wide variety of industries.
Lead author Saw-Wai Hla, a physics professor at Ohio University’s Nanoscale and Quantum Phenomena Institute, explains that earlier it was almost impossible to make nanoscale interconnects using metallic conductors because the resistance increased as the size of wire becomes smaller. “The nanowires become so hot that they can melt and destruct. That issue, Joule heating, has been a major barrier for making nanoscale devices a reality” [Xinhua], Hla says.
The mechanical energy produced when your body moves could be harnessed to power electronic gadgets thanks to what researchers are calling a “nanogenerator.” The nanotech device is made of tiny zinc oxide nanowires, which have piezoelectric properties–meaning that they generate a tiny electrical pulse when they’re bent, stretched, or otherwise subjected to mechanical stress. According to Zhong Lin Wang, lead researcher, the device could be used to charge gadgets such as iPods and BlackBerrys as well as having a impact on defence technology, environmental monitoring and biomedical sciences. “This technology can be used to generate energy under any circumstances as long as there is movement,” he said [Financial Times].
In a video demonstration, Wang attached a single nanowire to the back of a hamster and then hooked it up to an oscilloscope. As the rodent … scurried around, it generated 70 millivolts [the equivalent of .o7 volts]. When the critter stopped to lick itself, the power levels decreased [Wired].
Within a few decades, a surgeon may be able to make a tiny incision in a patient’s artery and insert a miniature robot that would scoot along through the blood vessel to the area of concern. The microbot could remove blockages, scrape plaque off of artery walls, remove a few cells from an organ to test for cancer, or could even, eventually, carry a tiny camera to show doctors exactly what’s going on inside the body. In a major step towards that science fiction-tinged surgical scenario, researchers have built and demonstrated a motor about twice the width of a human hair that could power such a microbot.
Researcher James Friend says that miniature mechanics have been a long time coming. “If you pick up an electronics catalogue, you’ll find all sorts of sensors, LEDs, memory chips etc that represent the latest in technology and miniaturisation,” he says. “Take a look however at the motors, and there are few changes from the motors available in the 1950s” [BBC News].
Doctors already snake catheters through blood vessels in many procedures to reduce the impact of surgery, but some blood vessels, like the labyrinthine network in the brain, are too narrow and delicate to reach with current technology. But a microbot might be able to reach even these most sensitive areas, and could one day be used to remove clots from stroke patients’ brains in the emergency room. The researchers have tested their motor in human blood and artificial arteries and later this year it will begin experiments in pigs, whose arteries and brains are similar to humans, before proceeding to full-scale human trials [Telegraph].