Hearing Aid Batteries
Without the development of hearing aid batteries, there would be no hearing aids as we know them today. It is the reduction in the size of battery cells that allowed for the creation of devices small enough to be worn in or around the ear.
To put it into perspective, at the time of the invention of the telephone, which had a microphone and speaker that were not very different in size than those used today, batteries were the size of a suitcase and produced relatively little power.
It meant that, to have a device that fit entirely within the ear canal, scientists and engineers had a much bigger job to reduce the size of the battery cells than to do so for any other major component, like the microphone and speaker – in addition to increasing power output significantly.
Every reduction in size made users more mobile. The wheeled devices that first allowed more mobility were followed by hand-held, then pocket-sized instruments, and eventually the devices we are more familiar with today.
The Zinc-Air Battery
Batteries work by converting the energy created by a chemical reaction into electrical energy. The cells hold the chemical(s) used for the reaction and are built in a way that allows the reaction and energy conversion to happen.
A number of different chemicals can be used to create the necessary reaction:
- Zinc-manganese or alkaline
Battery cells must be a certain size in order to the hold the chemicals in sufficient quantity for the reaction to happen.
A zinc-air battery takes one of its chemicals, oxygen, from the atmosphere and so does not need to carry two chemicals. This allows for greater miniaturization and is the main reason why they are predominantly used to power hearing aids.