Measuring NMR signals in fuel cells using small planar coils

At Keio University, the Ogawa Laboratory, in the Department of Mechanical Engineering, Faculty of Science and Technology, is working to establish technology for measurement inside fuel cells. The aim is to enable stable electric current generation in fuel cells, which have recently undergone rapid advances in development.

"With a fuel cell, if you actually want to measure it, that's very difficult: A fuel cell is made of metal, and it's hard to measure inside metal objects using MRI. So, what we do in our lab is, we use very small coils, and obtain signals by inserting those coils into the fuel cell. This method was invented by our group. We're working to develop a methodology; for example, obtaining a spatial distribution by arranging a very large number of such small coils, and using that spatial distribution to determine the water content in the polymer electrolyte membrane or the electric current generation in the fuel cell. At the same time, it's important for us to understand the principle of NMR and MRI; we need to effectively interpret the physical significance of the signal from the NMR equipment. When we do that, we can determine the spatial distribution of water content, or when the cell is operating, the spatial distribution of electric current generation."

One common type of fuel cell is the PEFC. To achieve stable electric current generation, the issues are devising a structure that doesn't obstruct gas flow, and removing the water that's generated by the chemical reaction of hydrogen and oxygen.

To resolve those issues, problems must be detected by making measurements inside the cell.

Currently, methods for measuring inside a sealed object include X-rays, neutron beams, and MRI. But all those methods require a large space, because they use bulky equipment. Also, because the fuel cell must be placed inside a magnet, the size of the cell is limited.

So, the Ogawa Lab uses a technique based on the NMR method, and places lots of small planar coils, covered with an insulating film, inside a fuel cell. This has made it possible to measure conditions inside the cell in detail, quickly, at multiple points. From now on, Professor Ogawa will improve and develop this technology, so it can be utilized in a wide range of other fields.

"For this method to become widespread, I think we need to prioritize making it quick and easy to do measurements. For example, we need to improve the human interface (How about "user interface"?), so measurement can be done just by clicking a mouse or pressing buttons.

We have to put together such a system carefully, from the user's viewpoint. Once we understand the principles, and have a methodology, the next step is to make a measuring device that's easy for people to use. "