Music within 200-500 Hz causes a cantilever in the device to vibrate. Strong bass, common in rap music, is especially suitable because of its low frequency sound. When the frequency falls below 200 Hz, the cantilever stops vibrating and electrical charge is transferred to the sensor.
The cantilever beam is made from lead zirconate titanate, or PZT, which is piezoelectric. Traditionally, medical implants are powered by batteries or receive power from coils and an external transmitter. The disadvantages of these methods are that batteries need to be replaced, and powering implants by inductance is difficult because the coils and the external receiver must be lined up and only about a centimeter apart.
The technology is suitable for medical sensors for blood pressure or urine pressure. The measurements can be made quickly and only a few minutes of music each hour would be required for the monitoring.Camilla Andersson