Piezoelectric materials convert mechanical energy into electrical energy, and electrical energy into mechanical energy. They generate electrical charges in response to mechanical stress and generate mechanical displacement and/or force when subjected to an electric current.
Scientists at NASA’s Langley Research Center have developed a piezoelectric device that is superior to many similar available devices. It is tougher, has far greater displacement and greater mechanical load capacity for a comparative voltage operation, can be easily produced at a relatively low cost, and lends itself well to mass production.
The NASA-developed piezoelectric device is unique in that it is more efficient in extracting electrical energy from the mechanical energy that goes in. It works on a simple principle. A thin ceramic piezoelectric wafer is sandwiched between an aluminum sheet and a steel sheet and held together with LaRC-SI, an amorphous thermoplastic adhesive with special properties created by NASA at Langley. The sandwich is heated in an autoclave, and the adhesive melts. When the sandwich cools, the adhesive bonds the parts together into one piezoelectric element. While they cool, the components of the element contract at different rates, since they are made of different materials.
This differential shrinkage causes the element to warp in either a convex or concave shape, depending on which way it is oriented. The shrinking of the outside metal layers places the inside piezoelectric ceramic under mechanical stress. If the element is cantilevered by clamping one side and then plucked, it reverberates like a diving board that has just ejected a diver.
This way, a small amount of mechanical energy can result in a relatively long period of electrical generation. When the piezoelectric element is used for the creation of electricity, it is called Lightning. This same sandwiched piezoelectric wafer can also convert electrical energy into mechanical energy. Then, it is called Thunder. Electricity goes in, excites the element, and then, mechanical energy in the form of movement is generated.
Partnership and Manufacturing
Face International Corporation of Norfolk, VA, holds several licenses to the Langley piezoelectric technology, including the patent on LaRC-SI and the exclusive international marketing rights. Face is now manufacturing a commercial version in mass quantities with its manufacturing partner, Sunnytec Company Ltd., at a new plant in Taiwan.
The first mass application of this piezoelectric technology is Face International’s Lightning Switch. The Lightning Switch is a wireless, battery-less, remote-controlled light switch — a way to install or replace light switches without any new wiring and without batteries. It is certified for use in the United States and Canada.
The Lightning Switch consists of a remote control transmitter that is modeled after a standard European light switch and a receiver that either plugs into an electrical socket or is wired into an electrical junction box. Pushing the button on the remote control generates enough electricity to send a coded radio signal to the receiver to switch on whatever is plugged or wired into the receiver.
Though the Lightning Switch was initially test marketed as a device for turning on and off holiday lights, customers have found many additional, clever uses for the switch. The majority of people have used it to install, replace, or rewire lighting controls without the hassle and cost of knocking holes in the walls and ceilings, or having to hire an electrician. The Lightning Switch installs in minutes and can save hundreds of dollars per switch in rewiring costs.
Other uses that customers have found for the device include a taxi-calling system for hotel bellmen; as a call-for-assistance system in assisted living facilities, nursing homes, and hospitals; a control lift for the elderly or disabled; and a signal for a casino table dealer to call for drinks or additional chips. Design-oriented entrepreneurs at retail establishments have used the Lightning Switch as a control for store fixture lighting, while art collectors have used it for backlighting framed pieces.
Lightning® and Thunder® are registered trademarks of Face International Corporation. Lightning Switch™ is a trademark of Face International Corporation.