Last June at Darnell’s Nanopower Forum, Face International demonstrated prototypes of its Lightning remote switching technology for home and business wiring (see “Zombies And Energy Harvesting” at www.electronicdesign.com, ED Online 15788). At that conference, Lightning was essentially a charge stored in clouds of hope. By the time of this year’s conference, though, Lightning had struck.
During the interim, the company turned the technology’s potential into actual sales of a range of products suitable for everything from retrofitting home light switching to allowing casino dealers to surreptitiously summon security agents. Face International, which still holds the NASA patent, spun the product business off as Lightning Switch, which is a more memorable name.
The Lightning Switch technology evolved from a NASA technology called Thunder, which was developed to create piezoelectric linear actuators with a relatively long throw. Being piezoelectric, the process is reversible. Lightning turns Thunder on its head, enabling the company to create switches with a long, satisfying mechanical “feel.” These switches can harvest enough electrical energy from each activation to power their own mesh network nodes, allowing remote control of whatever utility-powered device the end-user wishes.
The inverted-Thunder core technology addresses the problem of displacement in piezoelectric materials—how do you harvest a significant amount of piezoelectric energy while providing tactile feedback in a pushbutton switch? Essentially, Lightning answers the question with a thin ceramic piezoelectric wafer, sandwiched between an aluminum sheet and a steel sheet.
The “mayonnaise” in this piezoelectric sandwich is a thermoplastic adhesive. The process heats the adhesive to set it and permits the now-bonded structure to cool, bending and pre-stressing the piezo material. This provides a good quarter-inch of travel as well as enough energy to flash three NE-2 neon lamps in a tabletop demonstration (see the figure).
The value proposition for the technology lies in reducing construction costs. In one case, a 71,000-square-foot industrial facility needed 21 banks of lighting with associated control. The contractor originally bid $63,000, based mostly on the labor and overhead costs of installing more than a mile of couduit and switch wire. The contractor then bid again and won, using various Lightning products to complete the job for $10,000 for materials and 10 hours of labor.