Medical Implant Powered by Music
It is certainly an odd idea, but a rather effective one: Power a medical implant, with the beats of whatever song you happen to be listening to at the time. That in a nutshell is what Purdue university researchers have done with their latest prototype sensing device.
What the device senses doesn't actually matter. It could be a diabetics monitor, or an incontinence warning device. The base mechanics are the same, and it is literally powered by sound. Specifically bass sounds.
Created as a joint venture by doctoral student Albert Kim, research scientist Teimour Maleki and Professor Babak Ziaie, the sensor is a microelectromechanical system which is based on a vibrating cantilever. Basically, it is a thin beam attached to a larger sensor at one end like a miniature diving board. Music within a certain range of frequencies, from 200-500 hertz, causes the cantilever to vibrate, generating electricity on piezoelectric principles. This charge is then stored in a capacitor.
It could charge perfectly happily from a plain tone sounded at the correcrt frequency, and placed a few inches from the patient. However, that would quickly get on the patient's nerves. So, If they are going to use sound, why not use something a bit more pleasant to listen to?
Professor Ziaie stated as much. "A plain tone is a very annoying sound. We thought it would be novel and also more aesthetically pleasing to use music."
"The music reaches the correct frequency only at certain times, for example,
when there is a strong bass component," he said. "The acoustic energy
from the music can pass through body tissue, causing the cantilever to vibrate."
It doesn't even matter which songs you play, so long as they broadcast within the sensitive frequency range, at least part of the time. Listen to enough songs with a personal music player, and the device is fully charged.
In fact, the researchers experimented with four types of music: rap, blues, jazz and rock.
"Rap is the best because it contains a lot of low frequency sound, notably
the bass," Ziaie said.
The sensor is capable of monitoring pressure in the urinary bladder and in
the sack of a blood vessel damaged by an aneurism. Such a technology could be
used in a system for treating incontinence in people with paralysis by checking
bladder pressure and stimulating the spinal cord to close the sphincter that
controls urine flow from the bladder. More immediately, it could be used to
diagnose incontinence. The conventional diagnostic method now is to insert a
probe with a catheter, which must be in place for several hours while the patient
remains at the hospital.
In theory, the implant could be left in place permanently; only powering up when the patient hears music, and transmitting its data in between the valid frequency range pulses. If you listen to radio in the car whilst commuting each day, that is more than enough to keep it powered.
Findings are detailed in a paper, A Novel Electromechanical Interrogation Scheme for Implantable Passive Transponders to be presented during the IEEE MEMS conference.