Bass-heavy rap powers implantable medical sensors

A microelectromechanical system out of Purdue vibrates enough to generate power when subjected to sounds in the 200- to 500-hertz range. After testing the device using hip-hop, jazz, blues, and rock, researchers find "rap is the best."

To get in the mood for this one, I've put on an old favorite, a deep bass track by Dead Prez. It turns out the song's title, and main refrain--"It's Bigger Than Hip Hop"--applies to the power of music in a very literal sense as well.

A new type of pressure sensor includes a vibrating device called a cantilever, which generates a charge from acoustic waves to power itself. Purdue University

The acoustical vibrations that are particularly pervasive in the heavy bass lines of hip-hop penetrate our bodies and can then be captured and stored as electricity to power implanted medical devices. Researchers out of Purdue have built a device, which they are unveiling at the IEEE MEMS conference in Paris this week, that can power medical sensors after only a few minutes of exposure to sounds in the 200- to 500-hertz (that is, cycles per second) range.

"The music reaches the correct frequency only at certain times, for example when there is a strong bass component," said researcher Babak Ziaie, a Purdue University professor of electrical, computer, and biomedical engineering, in a news release. "The acoustic energy from the music can pass through body tissue, causing the cantilever to vibrate."

The new type of pressure sensor's 2-centimeter-long cantilever is made from a ceramic material called lead zirconate titanate, or PZT, which generates electricity when compressed. The cantilever is attached to one end of the sensor much like a miniature diving board.

When the frequency falls outside the 200- to 500-Hz range, the cantilever stops vibrating, thereby shooting the electrical charge to the sensor, which takes a pressure reading. Because sound frequencies are constantly changing, the sensor can alternate frequently between storing a charge and transmitting data via radio waves to a nearby receiver.

The team tested the device using hip-hop, jazz, blues, and rock. "Rap is the best because it contains a lot of low frequency sound, notably the bass," Ziaie said.

I personally love the idea of being exposed periodically to heavy bass lines of my choosing to keep charging medical implants instead of dealing with batteries that must be extracted from my body to be recharged. I'm not sure my grandmother, however, will be celebrating these findings.

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