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Researchers from the Georgia Institute of Technology have fabricated arrays of piezotronic transistors capable of converting mechanical motion directly into electronic controlling signals. The arrays could help give robots a more adaptive sense of touch. Mimicking the sense of touch electronically has been challenging, and is now done by measuring changes in resistance prompted by mechanical touch. The devices developed By Georgia Tech scientists rely on a different physical phenomenon – tiny polarization charges formed when piezoelectric materials such as zinc oxide are moved or placed under strain. In the piezotronic transistors, the piezoelectric charges control the flow of current through the wires just as gate voltages do in conventional three-terminal transistors.

“Any mechanical motion, such as the movement of arms or the fingers of a robot, could be translated to control signals,” explained Zhong Lin Wang, a Regents’ professor and Hightower Chair in the School of Materials Science and Engineering at the Georgia Institute of Technology. “This could make artificial skin smarter and more like the human skin. It would allow the skin to feel activity on the surface.”
Source: http://www.gatech.edu/

Researchers have developed a self-charging power cell that directly converts mechanical energy to chemical energy, storing the power until it is released as electrical current. By eliminating the need to convert mechanical energy to electrical energy for charging a battery, the new hybrid generator-storage cell utilizes mechanical energy more efficiently than systems using separate generators and batteries. For instance by harnessing a compressive force, such as a shoe heel hitting the pavement from a person walking, the power cell generates enough current to power a small calculator. A hybrid power cell the size of a conventional coin battery can power small electronic devices – and could have military applications for soldiers who might one day recharge battery-powered equipment as they walked.

“People are accustomed to considering electrical generation and storage as two separate operations done in two separate units,” said Zhong Lin Wang, a Regents professor in the School of Materials Science and Engineering at the Georgia Institute of Technology. “We have put them together in a single hybrid unit to create a self-charging power cell, demonstrating a new technique for charge conversion and storage in one integrated unit.”

The research was supported by the Defense Advanced Research Projects Agency (DARPA), the U.S. Air Force, the U.S. Department of Energy, the National Science Foundation, and the Knowledge Innovation Program of the Chinese Academy of Sciences.
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Source: http://gtresearchnews.gatech.edu/

Researchers from the Georgia Institute of Technology - GEORGIA TECH –  have discovered yet another way to harvest small amounts of electricity from motion in the world around us – this time by capturing the electrical charge produced when two different kinds of plastic materials rub against one another. Based on flexible polymer materials, this “triboelectric” generator could provide alternating current (AC) from activities such as walking.  And because these triboelectric generators can be made nearly transparent, they could offer a new way to produce active sensors that might replace technology now used for touch-sensitive device displays.

Diagram shows a new high-output, flexible and transparent trioboelectric nanogenerator produced from transparent polymer materials.

“The fact that an electric charge can be produced through this principle is well known,” said Zhong Lin Wang, a Regents professor in the School of Materials Science & Engineering at the Georgia Institute of Technology. "What we have introduced is a gap separation technique that produces a voltage drop, which leads to a current flow, allowing the charge to be used. This generator can convert random mechanical energy from our environment into electric energy.”

Source: http://gtresearchnews.gatech.edu/

Scavenging energy in our living environment is a feasible approach for powering micro/nanodevices and mobile electronics due to their small size, lower power consumption, and special working environment. Nanomaterials have shown unique advantages for energy conversion, including solar cells,  The type of energy to be harvested depends on the applications. For mobile, implantable and personal electronics, solar energy may not be the best choice because solar is not vailable in many cases under which the electronic devices will be utilized. Alternatively, mechanical energy, including vibration, air flow, and human physical motion, is available almost everywhere and at all times, which is called random energy with irregular amplitude and frequencies. Nanogenerator (NG) is a technology that has been developed for harvesting this type of energy using well-aligned nanowire (NW) arrays and sophisticated fabrication procedures,

 

Enjoy the video 

 

Pr. Zhong Lin Wang from Georgia Tech and his team present a simple, cost-effective, robust, and scalable approach for fabricating a nanogenerator that gives an output power strong enough to continuously drive a commercial liquid crystal display. 

Source: http://www.nanoscience.gatech.edu/zlwang/paper/2010/10_NL_06.pdf