Hearing aids suffer from short battery life because their sound-sensing microphones are inefficient at converting sound waves into electricity, partly because of the inertia of the microphone’s diaphragm.
Now researchers at the University of California in Oakland have an answer (WO 2004/18980). Instead of using a diaphragm, they propose a low-power microphone in which sound waves cause a flat, ribbon-like array of stiff optical fibres to vibrate like a microscopic springboard. One end of the fibres is anchored to an LED, while the free ends point at a photosensor. The light detected by the sensor corresponds to the vibration induced…
