{"484651":{"#nid":"484651","#data":{"type":"news","title":"Two-Stage Power Management System Boosts Energy-Harvesting Efficiency","body":[{"value":"\u003Cp\u003EA two-stage power management and storage system could dramatically improve the efficiency of triboelectric generators that harvest energy from irregular human motion such as walking, running or finger tapping.\u003C\/p\u003E\u003Cp\u003EThe system uses a small capacitor to capture alternating current generated by the biomechanical activity. When the first capacitor fills, a power management circuit then feeds the electricity into a battery or larger capacitor. This second storage device supplies DC current at voltages appropriate for powering wearable and mobile devices such as watches, heart monitors, calculators, thermometers \u2013 and even wireless remote entry devices for vehicles.\u003C\/p\u003E\u003Cp\u003EBy matching the impedance of the storage device to that of the triboelectric generators, the new system can boost energy efficiency from just one percent to as much as 60 percent. The research was reported December 11 in the journal \u003Cem\u003ENature Communications\u003C\/em\u003E.\u003C\/p\u003E\u003Cp\u003E\u201cWith a high-output triboelectric generator and this power management circuit, we can power a range of applications from human motion,\u201d said Simiao Niu, a graduate research assistant in the \u003Ca href=\u0022http:\/\/www.mse.gatech.edu\/\u0022\u003ESchool of Materials Science and Engineering\u003C\/a\u003E at the Georgia Institute of Technology. \u201cThe first stage of our system is matched to the triboelectric nanogenerator, and the second stage is matched to the application that it will be powering.\u201d\u003C\/p\u003E\u003Cp\u003ETriboelectric nanogenerators use a combination of the triboelectric effect and electrostatic induction to generate small amounts of electrical power from mechanical motions such as rotation, sliding or vibration. The triboelectric effect takes advantage of the fact that certain materials become electrically charged after they come into moving contact with a surface made from a different material. However, the output is alternating current, which can power applications such as LED lighting \u2013 but is not ideal for mobile devices.\u003C\/p\u003E\u003Cp\u003EOrdinary alternating current can be converted to direct current by using a transformer \u2013 but such a device requires consistency in the number of cycles per second. Because biomechanical energy sources such as walking or finger tapping produce fluctuating amplitude and variable frequencies, a standard transformer can\u2019t be used. In addition, the output from a triboelectric generator tends to have high voltage and low current \u2013 while applications for it require just the opposite: low voltage and higher current.\u003C\/p\u003E\u003Cp\u003ETo address the problem, Niu and collaborators under the supervision of Professor \u003Ca href=\u0022http:\/\/www.mse.gatech.edu\/faculty\/wang\u0022\u003EZhong Lin Wang\u003C\/a\u003E at Georgia Tech developed their power management system, which converts the fluctuating power amplitudes and variable frequencies to a continuous direct current.\u003C\/p\u003E\u003Cp\u003EThe power management system can work with any triboelectric generator that produces a minimum of 100 microwatts. The system requires some power to operate, but compensates by increasing the overall output as much as 330 times to reach milliwatt levels.\u003C\/p\u003E\u003Cp\u003E\u201cIt doesn\u2019t matter what kind of mechanical motion or what frequency of mechanical motion you have as long as the energy input is high,\u201d said Niu. \u201cThis is a critical step in the commercialization of triboelectric nanogenerators because it opens up a range of new applications.\u201d\u003C\/p\u003E\u003Cp\u003EWith finger tapping as the only energy source, the power unit provides continuous direct current of 1.044 milliwatts. The unit can work continuously with the motion, allowing devices to be operated even as the device charges the battery or capacitor.\u003C\/p\u003E\u003Cp\u003EBeyond portable electronics, Niu believes the system could be useful in powering networks of sensors, allowing long-term operation without the need for replacing batteries.\u003C\/p\u003E\u003Cp\u003E\u201cIn a sensor network, you would have so many devices that you could not replace all of the batteries,\u201d he said. \u201cThis technology would allow you to power the sensors by harvesting energy from the environment and then directly providing energy for each component of the network.\u201d\u003C\/p\u003E\u003Cp\u003EWith the energy management circuitry demonstrated in this proof-of-concept, the next step will be to miniaturize the circuitry to fit into an overall system, said Zhong Ling Wang, a Regents professor in the Georgia Tech School of Materials Science and Engineering who led development of the original triboelectric nanogenerators.\u003C\/p\u003E\u003Cp\u003E\u201cThis new device provides a bridge between the triboelectric nanogenerator and many different types of applications,\u201d he said. \u201cThis work will allow us to build a package that can power wearable and mobile devices from the motion of humans. With constant output from a battery or large capacitor, you can drive just about any device that you want.\u201d\u003C\/p\u003E\u003Cp\u003EThe power management system could also be applied to piezoelectric and pyroelectric generators, which also produce alternating current.\u003C\/p\u003E\u003Cp\u003EIn 2012, Wang and his research team announced triboelectric nanogenerators that produce small amounts of electricity from motion in the world around us \u2013 by capturing the electrical charge produced when two different kinds of plastic materials rub against one another. Based on flexible polymer materials, the triboelectric generators provide alternating current (AC) from activities such as walking.\u003C\/p\u003E\u003Cp\u003EVariations in generator structures allow a variety of applications depending on the source of mechanical energy. Wang\u2019s team has reported four major groups of generators including those that operate by (1) vertical contact-separation mode, (2) lateral sliding mode, (3) single-electron mode, and (4) freestanding triboelectric-layer mode. There are also hybrid combinations of these major structural modes.\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003ECITATION\u003C\/strong\u003E: Simiao Niu, Xiaofeng Wang, Fang Yi, Yu Sheng Zhou and Zhong Lin Wang, \u201cA universal self-charging system driven by random biomechanical energy for sustainable operation of mobile electronics,\u201d (Nature Communications, 2015). \u003Ca href=\u0022http:\/\/dx.doi.org\/10.1038\/ncomms9975\u0022\u003Ehttp:\/\/dx.doi.org\/10.1038\/ncomms9975\u003C\/a\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EResearch News\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003EGeorgia Institute of Technology\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003E177 North Avenue\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003EAtlanta, Georgia 30332-0181 USA\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EMedia Relations Contact\u003C\/strong\u003E: John Toon (404-894-6986) (\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E).\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EWriter\u003C\/strong\u003E: John Toon\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EA two-stage power management and storage system could dramatically improve the efficiency of triboelectric generators that harvest energy from irregular human motion such as walking, running or finger tapping.\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"A power management and storage system could boost energy harvesting."}],"uid":"27303","created_gmt":"2016-01-11 17:47:42","changed_gmt":"2016-10-08 03:20:24","author":"John Toon","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2016-01-11T00:00:00-05:00","iso_date":"2016-01-11T00:00:00-05:00","tz":"America\/New_York"},"extras":[],"hg_media":{"484611":{"id":"484611","type":"image","title":"Triboelectric nanogenerator","body":null,"created":"1452898800","gmt_created":"2016-01-15 23:00:00","changed":"1475895236","gmt_changed":"2016-10-08 02:53:56","alt":"Triboelectric nanogenerator","file":{"fid":"204284","name":"triboelectric_generator.jpg","image_path":"\/sites\/default\/files\/images\/triboelectric_generator.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/triboelectric_generator.jpg","mime":"image\/jpeg","size":502506,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/triboelectric_generator.jpg?itok=DzCiN2xm"}},"484621":{"id":"484621","type":"image","title":"Shoe with generator","body":null,"created":"1452898800","gmt_created":"2016-01-15 23:00:00","changed":"1475895236","gmt_changed":"2016-10-08 02:53:56","alt":"Shoe with generator","file":{"fid":"204285","name":"shoe-w-generator.png","image_path":"\/sites\/default\/files\/images\/shoe-w-generator.png","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/shoe-w-generator.png","mime":"image\/png","size":1351459,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/shoe-w-generator.png?itok=Y5G3dqI_"}},"484631":{"id":"484631","type":"image","title":"Nanogenerator powering calculator","body":null,"created":"1452898800","gmt_created":"2016-01-15 23:00:00","changed":"1475895239","gmt_changed":"2016-10-08 02:53:59","alt":"Nanogenerator powering calculator","file":{"fid":"204286","name":"calculator.jpg","image_path":"\/sites\/default\/files\/images\/calculator.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/calculator.jpg","mime":"image\/jpeg","size":554330,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/calculator.jpg?itok=yeu-gOJu"}}},"media_ids":["484611","484621","484631"],"groups":[{"id":"1188","name":"Research Horizons"}],"categories":[{"id":"144","name":"Energy"},{"id":"145","name":"Engineering"},{"id":"149","name":"Nanotechnology and Nanoscience"},{"id":"135","name":"Research"}],"keywords":[{"id":"13689","name":"energy harvesting"},{"id":"1334","name":"nanogenerator"},{"id":"37991","name":"triboelectric"},{"id":"13751","name":"Zhong Lin Wang"}],"core_research_areas":[{"id":"39451","name":"Electronics and Nanotechnology"},{"id":"39531","name":"Energy and Sustainable Infrastructure"},{"id":"39471","name":"Materials"}],"news_room_topics":[{"id":"71881","name":"Science and Technology"}],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003EJohn Toon\u003C\/p\u003E\u003Cp\u003EResearch News\u003C\/p\u003E\u003Cp\u003E\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E\u003C\/p\u003E\u003Cp\u003E(404) 894-6986\u003C\/p\u003E","format":"limited_html"}],"email":["jtoon@gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}