In just a short time, hearing aid batteries could be replaced by a drop of methanol.
Danish scientists are working on replacing the existing batteries in hearing aids with easily rechargeable fuel cells which run on methanol.
”We have come further than we ever could have hoped when we started this project of designing methanol-based batteries which can replace the traditional zinc batteries in hearing aids today”. That is what Leif Højslet Christensen, head of the Danish Technological Institute, and head of the project, says.
Recharging in 30 seconds
The vision of the project is that the batteries in a hearing aid should not need to be replaced for five years. Instead, one should simply take the hearing aid with its in-built fuel cell out and fill it with methanol for 30 seconds in a recharger. After this, it can be put back in the ear.
“Our realistic hope right from the start was to get a fuel cell to last for a month before it needed to be changed. Now, we have reached a life of five weeks. We are very satisfied with that,” says Leif Højslet Christensen.
”We are also very satisfied that we have developed a docking station – a recharger- about the size of a mobile phone, in which one opens the lid, puts the hearing aid in, closes it again and pushes a button, so that the fuel cells are refuelled with methanol.”
Leif Højslet Christensen explains, that they have already attached a hearing aid to a fuel cell via wires and can, in practice, say that the hearing aid runs on methanol. The goal now is to make the fuel cells small enough that they can be put directly in the hearing aid.
Perhaps ready by 2012
“We expect to launch the first fuel cells, which can be used directly in hearing aids, in 2012 – 18 months earlier than expected,” explains Leif Højslet Christensen.
There are around 40 million hearing aid users in the world. They use 3.7 million batteries per year, which today contain mercury. The more of these which can be replaced, the better it is for the environment.
Leif Højslet Christensen explains, that each fuel cell uses 1:100-200 thousandths of a litre of methanol in each recharging. According to him, the waste products are water vapour and carbon dioxide, which are both totally harmless to both people and the environment.
The Danish Technological Institute is working with scientists from DTU Nanotech in Copenhagen and Institute of Chemistry at the University of Aarhus.
Sources: Hørelsen 01, 2011 and Auris, 01, 2011