Tech Directions- October 2008

technology today Alan Pierce pierceaj@optonline.net Cloth Fibers that Generate Electricity In the next edition of our textbook Introduction to Technology, Dennis Karwatka and I deﬁne nanotechnology as the “science of working with the atoms and molecules of materials to develop very small machines.” To build these nanotech-size machines, scientists often draw on the knowledge of mechanical and electrical engineers, chemists, physicists, mathematicians, and experts in robotics. Nanotechnology projects often also involve other life science experts who manipulate atoms, molecules, and chromosomes. They change the very nature of certain bugs and turn them into useful factories that produce materials to beneﬁt humankind. Try to imagine a machine that is so tiny, about 100 nanometers in Georgia Tech image courtesy of Zhong Lin Wang and Xudong Wang Professor Zhong Lin Wang. The group developed paired nano textile ﬁbers that convert physical movement into electricity. The individual ﬁbers are microscopic in size. (See Photo 1.) But when you weave enough of them together you create a microﬁber nanogenerator that looks like thick threads. (See Photo 2.) If this new technology stays on track, you will eventually be able to purchase clothing that generates electricity by converting your physical movement into an electric current. Georgia Tech’s microﬁber nanogenerator is designed to be woven into any fabric. Imagine ﬂags ﬂapping in the wind, creating an environmentally clean inexpensive electricity. Perhaps windmill farms will one day have a competing technology that generates energy by harvesting the wind. The Georgia Tech team created their ﬁbers by growing zinc oxide nanowires on DuPont Kevlar ﬁbers. Their paired ﬁbers create piezoelectricity, electricity intertwined brushes. In some ways this graphic almost looks like a major magniﬁcation of the microscopic ﬁbers that appear in Photo 1. The bristles here represent the billions of microscopic bristles found on the real ﬁbers. These bristles are entwined so they touch each other when any motion is applied. This mechanical motion generates electricity. Polymer coatings protect the microscopic ﬁbers and their bristles. The goal now is to create a strong- Fig. 1—Graphic visualization of how a pair of fibers generate electricity enough coating so fabrics that contain these ﬁbers can stand up to repeated machine washing as well as the bending, twisting, and rubbing that causes them to generate electricity. The Georgia Tech fabrication process currently produces batches of ﬁbers that are about 3.5 microns long with a couple of hundred nanometer separation between each ﬁber. How small is a micron? A single strand of your hair is about 60 microns thick. Can you imagine wearing a power suit of clothing that constantly charges your personal electronic gadgets? Photo 1—Microscopic image of a paired fiber Photo 2—Professor Zhong Lin Wang holding a prototype of the microfiber nanogenerator size, that you need a very powerful microscope just to see it and its even smaller parts. To grasp the size, look at a single strand of your hair—it’s approximately a hundred thousand nanometers thick. A new nanotech machine has recently been announced by the Georgia Institute of Technology. It was created by a research group at the university under the direction of produced by stressing or applying pressure to certain types of materials. To tap the generated electricity, each pair of ﬁbers has a microscopic electrode that draws off the electricity that the ﬁber pairs generate. The illustration that Georgia Tech supplied can help you understand how these ﬁbers generate electricity. (See Fig. 1.) The microscopic paired ﬁbers are shown as yellow and green Georgia Tech image by Gary Meek Recalling the Facts 1. Fabric is often used as a wall covering. Could microﬁber nanogenerator threads be sewn into these fabrics to generate electricity? Why? 2. If your clothing generates electricity, do you think you will need to take special care not to receive electric shocks? Why? Alan Pierce, Ed.D., CSIT, is a technology education consultant. Visit www.technologytoday.us for past columns and teacher resources. www.techdirections.com TECHNOLOGY TODAY 11 Photo credit Georgia Tech http://www.technologytoday.us http://www.techdirections.com

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Tech Directions Technically Speaking Contents Direct from Washington The Report Technology's Past Technology Today Mastering Computers Automotive Power and Energy Technology Education Career Directions Electronics Special Feature More than fun

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