Energy Harvesting Shoes - Matching 2012

Just a quick overview of where this presentation is going to go. First, I’ll explain what exactly energy harvesting means. Next, I’ll explain some basics and such about piezoelectricity. Finally, I’ll go over sort of where piezoelectric energy harvesting can go in the future.
-So what is energy harvesting? Energy harvesting is a process by which energy is extracted from naturally occurring sources. Energy harvesting devices allow for the capturing, storing, conditioning, and managing of this extracted energy so that it can be used in a useful manner. -In a macro scale, energy can be harvesting from the naturally occurring sunlight and wind to provide large amounts of energy to power cities and such. -In a micro scale, energy can be harvested from mechanical energy- such as vibrations, mechanical stress, and strain- to power devices such as transmitters or wireless communication nodes. In the micro scale, energy can be harvested from electromagnetic devices and piezoelectric plates, among others. Because the energy harvesting topic is so broad, I’m going to specifically talk to you today about piezoelectricity. [3]
-When you deform the crystal as so *point to figure, electric power is attained. The crystal need only be strained 0.01% of the object’s volume for the piezoelectric plate to get any kind of power output. [5] - On the reverse end of it, a piezoelectric crystal can be deformed when an electric potential is given across its leads.
-Piezoelectricity is the production of electrical energy after a piezoelectric substance has been deformed as shown in the right. -When you deform the crystal as so *point to figure, electric power is attained. The crystal need only be strained 0.01% of the object’s volume for the piezoelectric plate to get any kind of power output. [5]
-Every piezoelectric plate’s output is different and varies on many factors including what type of crystal is being experimented on, how hard the object was deformed, in what way it was deformed, and the plate’s resistance among other things. Because of these variances, it is hard to characterize a piezoelectric plate’s output to one graph. -One other thing to note about piezoelectricity is that a plate is able to get a voltage in the order of thousands, but at the same time get only micro-amps out. -Given all this, here’s a sample of the piezoelectric plate’s output. It’s given for a piezoelectric plate similar to the one shown here. Two things just to note is that the power is in the range of milli-Watts and gets a maximum output at around 6000 Ohms. The resistance at which the power is maximum is the same as the piezoelectric plate’s resistance. Thus, this factor will vary too.
-2 slides back, I showed you a piezoelectric film. Now imagine getting piezoelectric plates even smaller than those films and you’ll get a zinc oxide nano-wire generator. Whenever the nano-wire gets any sort of vibration, it causes a voltage to come out of the generator. In 2005, this type of generated was initially experimented on to get voltage in the range of millivolts and a current even smaller than that. With enough engineering efforts put forth, a nanoscale power generator could be made to harness all the tiny vibrations in the environment around us. Examples include sound waves, the wind and even the turbulence of blood flow over an implanted device. These tiny vibrations could bend the nanowires and thus generate electricity. -All the devices shown on the right use the little generator on the left. -Going through each little bubble from left to right, the leftmost bubble shows arrays of little nano-wire generators that could be embedded in clothing and use the rustling of that clothing to power portable devices like iPods or cell-phones. -The bubble coming out of the guy’s ear shows a hearing aid being powered by the generator. Whenever sound waves hit the hearing aid, a voltage potential is generated across the generator. The sound waves get amplified with the voltage generated and after amplification, get sent to the auditory nerve. -The bubble coming out of the pad shows a grid of generators that could record the pressure applied by each person signing. In this way, signatures could be authenticated given a database in which to store the pressure patterns. -Finally, the last bubble coming out of his knee shows the generator being used as a sensor to monitor bone loss. Dangerous stress to the bone would generate power in the generator and would cause the device to send out an alert signal. These are just one of many ideas in this field of piezoelectricity. Some other ideas I’ve seen are using the plates to power transmitters, embedding generators in heavily populated walkways to harness the energy from the millions of steps from people walking, and so on.
References: [1]- “Piezoelectric Plate’s and Buzzers”, Oct. 17, 2009. [Online]. Available: http://jingfengele.en.alibaba.com/product/50917006-50159415/Piezoelectric_Buzzer_Plates.html [Accessed: Oct.17, 2009]. [2]- “Generating Electricity”, Oct. 17, 2009. [Online]. Available: http://www.edfenergy.com/powerup/keystage3/out/page4.html [Accessed: Oct.17, 2009]. [3]- “Queen of England Buys World’s Biggest Turbine”, Oct. 17, 2009. [Online]. Available: http://www.treehugger.com/files/2008/06/queen-offshore-wind-turbine-power-clipper.php [Accessed: Oct.17, 2009]. [4]- “NASA Invention of the Year’ Controls Noise and Vibration”, Oct. 17, 2009. [Online]. Available: http://www.sti.nasa.gov/tto/Spinoff2007/ip_9.html [Accessed: Oct.17, 2009]. [5]- “The Micro Fiber Composite (MFC)”, Oct. 17, 2009. [Online]. Available: http://www.smart-material.com/Smart-choice.php?from=MFC [Accessed: Oct.17, 2009]. [6]- Shashank Priya and Daniel J. Inman, “Energy Harvesting Technologies,“ New York: Springer, 2009, pp. 125. [7]- “TR10: Nanopiezoelectronics”, Oct. 17, 2009. [Online]. Available: http://www.microsystem.re.kr/main_kor/menu06/sub_menu02_view.asp?no=1158 [Accessed: Oct.17, 2009]. [8]- “Energy Harvesting Forum”, Oct. 17, 2009. [Online]. Available: http://www.energyharvesting.net [Accessed: Oct.17, 2009].

Energy Harvesting Shoes - Matching 2012

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