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---------------- 2742 - PIEZOELECTRICITY - electricity from sound waves?
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- Our energy problems could be solved. How? ………… By vibrating piezoelectric crystals we can generate electric power. All buildings and structures have a natural resonance of vibration powered by the wind. Paint the building with piezoelectric crystals and the slightest movement could power the building’s electric requirements.
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- When Hewlett-Packard Company moved its microelectronic production into a new building in Fountaingrove Parkway, Santa Rosa, CA, the production lines were on the second floor. The operators using 600 power microscopes to assemble the microcircuits could not work because the vibration was blurring the image under the microscope.
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- Production was moved to the basement floor. Still the vibrations were an annoyance. Finally, a concrete saw was used to make a gap around each beam structure isolating the concrete floor from the rest of the building. With nano-piezoelectric crystals those same vibrations at the natural resonance of the building could be generating electric power.
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- Piezoelectric crystals can turn mechanical energy into electric energy. And, vice versa, they can turn electric fields into mechanical movements. Piezoelectric materials include sugar cane, quartz, dried bone, and, zinc oxide (like that used in calamine lotion). These materials create an electric charge when stressed. They are commonly used in speakers, microphones, strain gauges, and scanning tunneling microscopes.
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- Piezoelectricity was first discovered in 1880 by Pierre Curie. Today, nanotechnology is putting a new life into the phenomena. New devices are being developed. The U. S. Army is even testing powering electric vehicles that can channel the physical impact of bullets, or rough terrain into electric current to further power the vehicle. The more the enemy fires the faster the vehicle goes after them. Wow!
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- Zinc Oxide crystals are being used in cell phones. Nanowires sandwiched between two electrodes can turn sound waves entering the phone into 50 millivolts of electrical voltage. 100 dB of sound creates 50 millivolts of electric potential.
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- A normal conversation is about 70 dB, and current cell phones need 2,500 millivolts to operate. There is a ways to go, form 50 to 2,500. However, current research is young and engineers are confident they can close the gap for commercial uses of piezoelectric crystals to power devices.
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- Of course, quartz crystals have been around for a long time in quartz watches. To be used in a time piece the crystal is cut along its “piezo axis”. The “piezo” property of a crystal is its electrical property.
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- In this case an applied electric field causes the crystal to flex. The amplitude of the flex is largest at the resonant frequency of the crystal. The electric circuits in the watch sense where the energy is greatest creating a feedback current at the fixed resonant frequency.
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- It is that single frequency that keeps the watch’s time accurate. The frequency accuracies of a watch can be maintained at one part in 1,000,000. In a laboratory, with temperature controls, quartz accuracies can be maintained at one part in 10,000,000,000.
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- Piezoelectric crystals are also used in Scanning Tunneling Microscopes because they can expand and contract in an electric field to control movements within 0.00001 nanometers. This level of accuracy has allowed scanning microscopes to map out individual atoms at the surface of a material.
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- How can a crystal create mechanical and electrical properties? The crystal is made up of positively and negatively charged particles arranged in a lattice or an orderly fashion. If two opposite faces of a crystal are placed under pressure, squeezed together, the distortion can push charged particles to move closer together, or farther apart. The particles change position but remain distributed about the same central point.
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- If the average position of the negatively charged particles shifts slightly with respect to the average position of the positively charged particles a voltage differential is produced between the two faces of the crystal.
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- The situation can be reversed by pacing the crystal in an electric field so that a potential difference exists across the crystal. The crystal will distort accordingly. If the voltage alternates the crystal will vibrate. Its vibration will be greatest at the crystal’s natural resonant frequency. The vibrations can be used to produce sound waves as in a speaker, or the opposite as in a microphone.
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- When engineering gets the nanotechnology perfected with piezoelectric devices, talking into a cell phone alone could charge it. Traffic noise could be harnessed to add electricity to the city’s electrical grid. Buildings could produce their own electricity.
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- What will today’s students in science and engineering come up with in the next decade? It is hard to imagine. Imagination is more important than knowledge. Kids have unbridled imaginations. Stay tuned, there is a lot more to come.
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----------------------------------- Other Reviews using nanotechnology:
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- 2622 - - NANOTECHNOLOGY - solar cells from nanowires? Energy is the number one problem we will face. In one year the world uses 14,500,000,000,000 watts of power. Most of this energy is generated using gas and oil. Only 1 % of our energy comes from solar, wind, or geothermal. In the year 2050 we will be using somewhere at least 30,000,000,000,000 watts of electricity.
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- 2621 - NANOTECHNOLOGY - in quantum mechanics.? - Today nanotechnology is being used by countless universities and corporations to create products that will be entering the commercial markets, soon. Nanotechnology will be found in information technology, communications, biology, medicine, and energy. You will likely see the changes in biology and medicine first.
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- 1230 - Nanotube Weirdness of the Very Small? As astronomers search the very big we find weirdness, 95% of which is not understood. The same happens in the other directions as physicists search the very small atoms and molecules do not behave like we expect. Nanotechnology weirdness will go commercial before we ever understand how it works. It will be even better when we understand it.
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- 851 - The Nanotube Radio. A whole new radio has been invented using nanotechnology. The radio is so small it cannot be seen without the aid of a microscope. The radio is a single carbon nanotube that is much smaller than a wavelength of light. The nanotube is a few nanometers in diameter and 10 to 100 nanometers in length.
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- May 20, 2020 1197 2742
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