Three of the six companies that dominate the global hearing aid market are Danish, so it's an area of technological development that Denmark can exploit without too much risk of competition from the rest of the world. That is exactly the thinking behind a project launched by the Danish Technological Institute to develop a methanol powered micro fuel cell for hearing aids to replace the traditional button battery, writes professional journal Ingeniøren (The Engineer).
DKK 15m (USD 2.9m) in support funding for the project is coming from the Technological Institute itself, while the Ministry for Science, Technology and Innovation has previously put DKK 42m (USD 8m) into new clean room facilities at DTU Danchip which can be used for high tech device production. Other parties collaborating in the project include Danish hearing aid manufacturer Widex, DTU Nanotech, Aarhus University Department of Chemistry and the Interdisciplinary Nanoscience Center iNano at Aarhus University.
The micro direct methanol fuel cell (mDMFC) is a known technology, but the challenge of making one small enough to fit into a hearing aid, and with enough performance power and duration to challenge the traditional zinc-air button battery has not yet been attempted. That is what this project will now take on, with the aim of completing a working prototype in 18 months and a further 4-6 years to produce a marketable product.
One of the particular challenges facing the project is how to get the polymer membrane that separates the anode and cathode thin enough to enable the size of the mDMFC sufficiently miniaturised to fit in a hearing aid. This is where nanotechnology comes in - it is hoped that the science will enable a super-thin membrane to be produced that will provide the proton transmission function without allowing methanol to 'leak' through to the cathode.
The aim with the mDMFC is to produce a power unit for the hearing aid that can be refuelled with methanol in a matter of seconds in an automatic refiller, thus avoiding the fiddling and fumbling with small button batteries that is far from an easy task especially for the arthritic elderly. Each refill should deliver enough power to last approximately the same length of time as a typical zinc-air battery, which is non-rechargeable.