Piezoelectrics: A New Way to Produce Electricity - Texas

Ever since electricity was harnessed and understood by humans, we have found new ways to generate it and put it to use. There was the Baghdad Battery, then lightning rods, and now there is the advanced science of piezoelectrics. Energy, of course, cannot be created or destroyed, but can be transferred from one kind to another. Piezoelectrics allow mechanical energy to become electricity, unlocking new possibilities for personal power sources. The stress applied to some kinds of material, including crystals, ceramics and more can be put to practical use, thanks to the efforts of creative, cutting-edge scientists.

The first half of the word "piezoelectricity" comes from the Greek word meaning "push," reflective of the manner in which the electricity is generated. (The second half, of course, comes from the Latin electricus, meaning "amber-like," as rubbing fur on amber was one early way to get those sparks people didn't yet understand.) According to physicists at Georgia State University, the piezoelectric effect was first discovered in 1880 by Pierre and Jacques Curie. (Pierre, of course, was the husband of Marie Curie, a brilliant woman who helped us understand, and subsequently use, radioactivity.)

Piezoelectric materials generate electricity when put under mechanical stress. Some of the materials that exhibit this useful property include crystals and ceramics. (Of these, quartz is the best-known.) There are many other such materials, however, including topaz, cane sugar, silk, wood and even bone. You may not even know it, but you benefit from piezoelectric materials every day. Automobile air bags contain piezoelectric sensors; when your car experiences the trauma of a crash, the mechanical stress generates the electricity necessary to trigger the explosives that ignite the airbag. A much more pleasant application can be found in some guitar pickups. The sound waves generated by your strumming move the wood in the body of guitar, triggering the piezoelectric pickup, allowing your jam to be heard through an amplifier.

People are always looking for new ways to power their twenty-first century lifestyles. While our homes have a huge power requirement, people have a growing need for portable electricity. (Think about it: we all love our cell phones, MP3 players, laptops, PDAs and more.) The future will be much easier for everyone with increased energy independence from clean sources. Sure, the national and regional grids will be independent, then neighborhoods and households, but what if you were able use your body's mechanical movement to power the devices you need?

According to Science Daily, a team of scientists at the University of Houston is devoting their time to developing piezoelectric devices for even more practical applications. The benefits are many: in addition to providing their own electric current, these devices are lighter, more convenient and put less stress on the environment. There are also lots of out-of-the-way devices for which piezoelectrics are a great convenience, if not a necessity. Science Daily quotes one of the students on the project, Pradeep Sharma, with respect to the end results of his work: "Imagine a sensor on the wing of a plane or a satellite. Do we really want to change its battery every time its power source gets exhausted? Hard-to-access devices could be self-powered."

While keeping in touch and listening to our tunes is important, piezoelectricity would be put to even better use in biomedical devices. Imagine a pacemaker that is self-powered, eliminating bulky batteries and the complications that arise when implanting them.

Every time you take a step, the piezoelectric bones and cartilage in your body generate slight amounts of electricity, and there is also mechanical energy you exert on your shoes. Implanted with the right metals and materials, this energy could be conducted to a battery in a backpack or elsewhere. This person-charged battery would mean that keeping your cell phone operational could be accomplished just by moving around.

Unfortunately, the best of these applications are still in the future. Scientists have tried to create clothing with piezoelectric materials, but haven't yet had much success. An article in the Toronto Star profiled one of the successes: piezoelectric mats on the floors of Tokyo train stations. All those people filing on and off the train hit the mat, releasing energy from the materials. The electricity is used to power the ticket gates and arrival and departure monitors. The same principle is being put to use in a club in London, whose floors are impregnated materials that keep the music going when dancers hit the floor.

These examples prove that the basic science behind piezoelectricity is sound. All that remains is for the scientists of the present to provide solutions for a self-powered future.