Eagle's Eye: Self-powered devices

Imagine a self-powering cell phone that never needs to be charged because it converts sound waves produced by the user into the energy it needs to keep running -Dr SS Verma
In an electrical power dependent lifestyle, self-powered devices have always been of a great curiosity for mankind and more due to man's growing dependence with electronic gadgets. We see all around us circuitry required to power such devices which in some cases have been replaced by batteries. Power from any source is either inefficient or limited and is being associated with the exploitation of natural resources. Efforts to make use of non-conventional sources of energy to provide power also have surmounted limitations so far. With the depleting conventional energy sources, degrading environment and in-efficient non-conventional sources, there is a need to develop technologies to make use of waste energy or freely available energy with suitable technological advances to convert it into electricity which can be used to power the electronic devices of our dependence. Imagine a self-powering cell phone that never needs to be charged because it converts sound waves produced by the user into the energy it needs to keep running. Thanks to the recent recognizable work of Prof. T Cagin in the Artie McFerrin Department of Chemical Engineering at Texas A&M University (USA) on nanotechnology piezoelectronics to convert so called waste mechanical energy into electricity in order to realize the aim of self-powered devices. 
Piezoelectricity is the ability of some materials (notably crystals and certain ceramics) to generate an electric potential in response to applied mechanical stress. This may take the form of a separation of electric charge across the crystal lattice. If the material is not short-circuited, the applied charge induces a voltage across the material. The first demonstration of the direct piezoelectric effect was in 1880 by the brothers Pierre Curie and Jacques Curie. For the next few decades, piezoelectricity remained something of a laboratory curiosity. Piezoelectrics were first used in sonar devices during World War I. The effect finds many useful applications such as microphones, quartz watches, the production and detection of sound, generation of high voltages, electronic frequency generation, microbalances, and ultra fine focusing of optical assemblies. It is also the basis of a number of scientific instrumental techniques with atomic resolution i.e., and everyday uses such as acting as the ignition source for cigarette lighters and push-start propane barbecues. On a grander scale, some night clubs in Europe feature dance floors built with piezoelectrics that absorb and convert the energy from footsteps in order to help power lights in the club. And it's been reported that a Hong Kong gym is using the technology to convert energy from exercisers to help power its lights and music. While advances in those applications continue to progress, piezoelectric work at the nanoscale is a relatively new endeavor with different and complex aspects to consider.
There are many materials, both natural and man-made, exhibiting piezoelectricity. A significant change in scale of materials (i.e., nano-size) makes the materials to react differently. When materials are brought down to the nanoscale dimensions, their properties for some performance characteristics dramatically change and one such example is with piezoelectric materials. Utilizing piezoelectric materials with nanotechnology concepts has made a significant discovery in the area of power harvesting  a field that aims to develop self-powered devices that do not require replaceable power supplies, such as batteries. Researchers have found that a certain type of piezoelectric material can covert energy at a 100 percent increase when manufactured at a very small size  in a quoted special case, around 21 nanometers in thickness. However, when materials are constructed bigger or smaller than this specific size show a significant decrease in their energy-converting capacity. Nano-piezo electricity could have potentially profound effects for low-powered electronic devices such as cell phones, laptops, personal communicators and a host of other computer-related devices used by everyone from the average consumer to law enforcement officers and even soldiers in the battlefield as many of these high-tech devices contain components that are measured in nanometers. 
Nanotechnology researchers have proposed and developed a broad range of nanoscale devices, but their use has been limited by the sources of energy available to power them. Conventional batteries make the nanoscale systems too large, and the toxic contents of batteries limit their use in the body. Other potential power sources also suffer from significant drawbacks. By converting mechanical energy these "nanogenerators" (i.e., making use of nano-piezoelectronics) could make possible a new class of self-powered implantable medical devices, sensors and portable electronics. There is a lot of mechanical energy available in our environment and nanogenerators can convert this mechanical energy to electrical energy. This could potentially open up a lot of possibilities for the future of nanotechnology and piezoelectronics. Few areas under immediate attention for the use of nano-piezoelectronic devices are:
Discovery of nano-piezo electronics stands to advance nanotechnology research that has already grown increasingly popular due to consumer demand for compact portable and wireless devices with extended lifespans.
Beyond mere consumer convenience, self-powering devices are of major interest to several federal agencies also. In this direction, investigations are going on to develop methods for soldiers in the field to generate power for their portable equipment through the energy harvested from simply walking. And sensors  such as those used to detect explosives  could greatly benefit from a self-powering technology that would reduce the need for the testing and replacing of batteries.
Even the disturbances in the form of sound waves such as pressure waves in gases, liquids and solids may be harvested for powering nano- and micro devices of the future if these materials are processed and manufactured appropriately.
This could also open up tremendous possibilities for self-powered implantable medical devices.
The next step in the research will be to develop new nano-piezoelectric materials which can maximize the conversion of mechanical energy into electrical energy for a single cycle of vibration and its total collection for useful purpose.  
Dept of Physics, SLIET, Longowal