Nanogenerators

Nanogenerators will be needed to power the new generation of tiny devices that nanotechnology is producing. Just as the self-winding wristwatch collects kinetic energy and uses it to drive the spring in the watch, it is possible to collect small amounts of energy in a variety of ways: motion and vibration, thermal differences, sonic waves and it is even possible for bio-generators to tap into the energy stored in a body through chemistry.

Nanogenerators grow strong enough to power small conventional electronics (w/ Video) – [physorg.com]

In this case, the mechanical energy comes from compressing a nanogenerator between two fingers, but it could also come from a heartbeat, the pounding of a hiker’s shoe on a trail, the rustling of a shirt, or the vibration of a heavy machine. While these nanogenerators will never produce large amounts of electricity for conventional purposes, they could be used to power nanoscale and microscale devices – and even to recharge pacemakers or iPods.

Wang’s nanogenerators rely on the piezoelectric effect seen in crystalline materials such as zinc oxide, in which an electric charge potential is created when structures made from the material are flexed or compressed. By capturing and combining the charges from millions of these nanoscale zinc oxide wires, Wang and his research team can produce as much as three volts – and up to 300 nanoamps.

A New Nanogenerator – [technologyreview.com]

Wireless biosensors that monitor pathogens in water and measure blood pressure or cancer biomarkers in the body are shrinking to nanometer dimensions. To operate them, researchers are looking for equally small power sources. Nanowires that convert mechanical energy into electricity are a promising technology.

Now researchers at the University of Illinois at Urbana-Champaign (UIUC) have taken the first step toward building a nanogenerator out of barium titanate. So far, efforts to make nanogenerators have focused on zinc-oxide nanowires. But barium titanate could lead to better generators because it shows a stronger piezoelectric effect, says mechanical-science and engineering professor Min-Feng Yu, who is leading the research at UIUC. Lab experiments show that a barium-titanate nanowire can generate 16 times as much electricity as a zinc-oxide nanowire from the same amount of mechanical vibrations, he says.

Nanogenerator Powers Up – [techreview.com]

Devices that harvest wasted mechanical energy could make many new advances possible—including clothing that recharges personal electronics with body movements, or implants that tap the motion of blood or organs. But making energy-harvesting devices that are compact, flexible, and, above all, efficient remains a big challenge. 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.

The generators take advantage of materials that exhibit a property called piezoelectricity. When a piezoelectric material is stressed, it can drive an electrical current (applying a current has the reverse effect, making the material flex). Piezoelectrics are already used in microphones, sensors, clocks, and other devices, but efforts to harvest biomechanical energy using them have been stymied by the fact that they are typically rigid. Piezoelectric polymers do exist, but they aren’t very efficient.

How Self-Powered Nanotech Machines Work – [scientificamerican.com]

The watchmaker in the 1920s who devised the self-winding wristwatch was on to a great idea: mechanically harvesting energy from the wearer’s moving arm and putting it to work rewinding the watch spring.

Today we are beginning to create extremely small energy harvesters that can supply electrical power to the tiny world of nanoscale devices, where things are measured in billionths of a meter. We call these power plants nanogenerators. The ability to make power on a minuscule scale allows us to think of implantable biosensors that can continuously monitor a patient’s blood glucose level, or autonomous strain sensors for structures such as bridges, or environmental sensors for detecting toxins—all running without the need for replacement batteries. Energy sources are desperately needed for nanorobotics, microelectromechanical systems (MEMS), homeland security and even portable personal electronics. It is hard to imagine all the uses such infinitesimal generators may eventually find.

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