Bio Focus: Fly-inspired PZT sound detector
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Bio Focus Fly-inspired PZT sound detector
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team of researchers at The University of Texas at Austin (UT Austin) has developed a tiny prototype device that mimics the hearing mechanism of a parasitic fly, the yellow-colored Ormia ochracea. This development may be useful for a new generation of hypersensitive hearing aids. Described in the July 22 online edition of Applied Physics Letters (DOI: 10.1063/1.4887370), the 2-mmwide device uses piezoelectric materials, which turn mechanical strain into electric signals. The use of these materials means that the device requires very little power. The space between the ears of insects is typically so small that sound waves essentially hit both sides simultaneously. However, the O. ochracea has an unusual physiological mechanism in which the sound phase shifts slightly when the sound goes in one ear and when it goes in the other. The fly, whose ears are less than 2 mm apart, has an ear structure that
t Bio Focus Conducting polymers utilized to overcome electrode limits in ionic transport systems
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he transport of particles through a fluid by an electric current, known as electrokinetics, is a process used in a number of well-known applications such as gel electrophoresis and drug delivery systems. These types of ionic conductors operate based on the interaction of a direct current (DC), applied between metal
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be incorporated into a more complex machine with neural connections regulating the muscle cells. “Our next step is working to integrate neurons into the structure, so you could provide a signal to the neuron and the neuron would control the movement,” he said. “It’s clear that there’s an opportunity to take technological advances and combine
resembles a tiny teeter-totter seesaw about 1.5 mm long. Teeter-totters, by their very nature, vibrate such that opposing ends have a 180° phase difference, so even very small phase differences in incident pressure waves force a mechanical motion that is 180° out of phase with the other end. This effectively amplifies the fourmillionths of a second time delay the O. ochracea experiences in its hearing. Neal Hall, an assistant professor in the Electrical and Computer Engineering Department at UT Austin, and his graduate student Michael Kuntzman built a miniature pressure-sensitive teeter-totter in silicon that has a flexible beam and integrated piezoelectric materials. By using multiple piezoelectric sensing ports, the researchers enable numerous vibration modes which then amplify the interaural time and level differences such as the fly experiences. The use of piezoelectric materials was their original innovation, and it allowed them to simultaneously measure the flexing and the rotation of the teetertotter beam. Simultaneously measuring these two vibration modes allowed the
electrodes and charged ions suspended in a fluid. This process, however, can have a number of critical drawbacks such as the production of chemical side products or gases that may impede particle movement.
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