In 1880, Pierre and Jacques Curie discovered that certain crystals generate a charge when pressed. They deemed them piezo crystals, from the Greek for “press.” Piezoelectric crystals are transducers that turn mechanical energy into electricity. Conversely, they respond to electrical charges by expanding or contracting.
But traditional piezoelectric compounds are bulky, brittle and inefficient. They convert no more than 40 percent of mechanical energy to electricity. When subjected to an electrical field or current, they expand or contract, but only by tiny amounts.
Advanced Cerametrics piezoelectric fibers, on the other hand, are flexible. They weigh as little as two grams for a transducer that can generate 40 volts. They pick up a wider range of vibration frequencies, and generate 75 percent more power from those vibrations. And Advanced Cerametrics piezoelectric fibers outperform bulk piezos as electricity-to-motion transducers. They exert a stronger mechanical force over a larger range of motion at just 35 percent the weight. A two-gram active fiber composite strip can produce a blocking authority of 60 pounds!
Advanced Cerametrics manufactures is piezoelectric fibers of lead zirconate titanate, or PZT. Applications for PZT fibers fall into the two broad categories, energy harvesting or actuation. Specifically, a few opportunities stand out.
Most sensors are in environments were ambient waste mechanical energy is abundant, whether it’s inside an air duct or mounted on a motorized system. Advanced Cerametrics PZT fibers harvest that mechanical energy to recharge the batteries or power the sensors directly, without batteries.
Applications for auto-powered monitoring range from aerospace to automotive to home appliances to biomedicine.
The higher output power of Advanced Cerametrics piezoelectric fibers opens many opportunities to power electroluminescent lighting on bridge decks, signage and buoys, among other applications.
Advanced Cerametrics PZT composites turn motion into power and power into motion. Vibration damping uses both characteristics. When vibrations generate power, built-in circuitry relays the charge to a microprocessor, which measures the magnitude of the vibration and returns an amplified signal that either stiffens or relaxes the fiber actuators. They qualify as “smart systems” for their self-adjusting nature.
In one of the best-known applications of vibration damping is by Head Sport AG of Kennelbach, Austria. Head uses Advanced Cerametrics PZT fiber composites to reduce tennis racket vibration and ski chatter.
Advanced Cerametrics PZT fiber composites have a range of motion that opens entirely new vistas for energy-to-motion actuation. For example, piezoelectric fibers have been used to bend small aircraft wing flaps as much as 22 degrees without hydraulics.
Conventional bulk piezos move such tiny amounts that, when used as actuators, they typically require intermediating mechanisms that amplify movement. The greater range of motion of fiber piezos may allow engineers to skip these intermediating devices.
The technology is advancing fast. In our energy-hungry, battery-powered world, the19th-century piezoelectric materials have had little to contribute. But flexible piezoelectric fibers from Advanced Cerametrics offer 10 times the power output of older forms. They can be shaped in ways the user defines. They’re lighter, more sensitive and have greater actuation potential.
With these new fibers in the picture, we’re sure to see a rush of technologies that capitalize on their properties.