portable power
sible from the potentially low-level charge generated and stored by the energy harvester. Figures 1 and 2 compare energy accumulation and recovery time with input vibration amplitude.
figure 2 Energy Recovery Time vs. Input Vibration Amplitude (Capacitive Storage Version, Following Full Discharge of ET=3.9 mJ)
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Energy recovery time vs. input vibration amplitude
Sensor-transmitters powered by harvested energy are key to providing low-cost ambient intelligence that can sense, monitor and report conditions in factories, offices, vehicles, residences, shopping malls, traffic centers—in short, virtually all types of human environments and some natural ones, as well. Out of companies providing solutions now thethehundreds of from millions of wireless sensor exploration into products, technologies and companies. Whether your goal is to research latest datasheet a company, each year, alevel steadily increasing mp to a company's technical page, the goal of Get Connected is to put you in touchnodes with theinstalled right resource. Whichever of gy, Get Connected will help you connect with the companies and products you arenumber searching for. are being powered by harvesting the onnected energy of motion. Structural monitoring is important not only in bridges, but also in constructions such as high-rise buildings and stadiums where undetected fatigue in uprights and beams can lead to disaster. In factory motors and other machinery, the sensors could alert personnel of wornout bearings and other problems that require maintenance, thus predicting failure, helping to avert costly breakdowns and aiding in extending the life of equipment. Get Connected with companies mentioned in this article. The potential rewards are high: equipment www.portabledesign.com/getconnected industry sources estimate that preventive main-
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PORTABLE DESIGN
Get Connected with companies mentioned in this article.
tenance through asset monitoring can save tens of billions of dollars annually—perhaps as much as five percent of the more than $1.3 trillion that is spent every year in the U.S. for mechanical maintenance. Other savings come from greater power efficiency in operation, less frequent replacement of machinery, and savings in unproductive time in the factory when equipment is down. In automobiles, wireless sensors powered by vibration could extend safety features while helping to reduce some of the 300 to 500 pounds of wiring that go into every car that rolls off the assembly line. Vibration-powered tire pressure monitoring systems would eliminate the need for the batteries used in the current systems. As important as energy harvesting sensors can be in cars and trucks, they may matter even more to the aviation industry. Along with other functions, the sensors enable monitoring the integrity of an aircraft frame for safety, even from concealed or remote spaces that are largely inaccessible, or where temperatures are extreme. Every foot of wiring in a commercial plane costs some $2,000 for installation and lifetime maintenance—not including the fuel to carry it or the batteries that might serve as an alternative. By eliminating wiring and batteries, vibrationpowered sensors with wireless transmission can save a lot of money for a cost-conscious industry, where it is vital to keep weight, space and fuel consumption to a minimum. The movement that Joule-Thief uses to capture energy can come from motion sources other than mechanical vibration, such as pressure or air flow; and the output can be used to power sensors for temperature, chemistry, light, humidity and other environmental conditions besides vibration. Building automation enabled by the sensors could cut energy costs while making homes and workplaces greener and more comfortable. Railroad cars and shipping containers can use vibration-powered devices as a form of active radio frequency identification (RFID) to aid in tracking. Ultimately the technology may be employed in human apparel to reduce the number of batteries we carry—an application that would be especially important for lightening the load of soldiers on the battlefield. In addition, AdaptivEnergy has entered into a strategic agreement with In-Q-Tel, a company that identifies innovative technology to support the