HOW TO – Build your own band aid fuel cell

Build a Fuel Cell with a couple of Band Aids, an MEA and a few scraps of stainless steel bug screen by Gavin D. J. Harper.

The story as to how this design came into being is probably a little too much information, but worth sharing none the less. Having spent some time playing with Fuel Cells on the bench, I went to the bathroom with the quote from Lawrence Burns, the GM vice president for research and development ringing through my ears…

“The fuel cell, offers a cure, not a Band-Aid.”

Looking around the room, my eyes clapped on a box of Band Aid, suddenly it dawned on me that the Fuel Cell could indeed offer a band aid.

This has got to be THE simplest way to build a fuel cell from scratch. The design is ridiculously simple, whilst being effective – it will allow you to explore the concepts of Fuel Cells in a ludicrously simple way.

It might sound preposterous, it might sound absurd, but it works!Bits List:

2 nice big band aids

Think Rite Aid or Walgreens. These are just your bog-standard band aids. Don’t get ones that are impregnated with aloe vera or any special ointment, it will simply gunk up the works. Just get plain old band aids. You want one with a nice big area for the “wound”.

Stainless Steel Fly Screen

If you want to get really techie and heavy about stainless steel fly screen, the material that I used was top-notch stuff! The stainless steel was 318 grade – very high quality!! The screen was 72 wires per inch in both directions, with each wire being 0.0037″. This wire is available from the folks at the totally fabby www.fuelcellstore.com.

MEA – The Membrane Electrode Assembly

MEA stands for “Membrane Electrode Assembly”, this is the bit that “does the works”. You can make your own, they are rather difficult to assemble, much simpler is to buy one that is already made from www.fuelcellstore.com. This is what you get for your money: A piece of Nafionâ„¢… Wiki all about it here , this posh plastic is technically known as a sulfonated tetrafluorethylene copolymer… Let’s look a little more closely at the plastic bag.

The Blurb on the MEA Package

The large DMFC tells you that the fuel cell is a direct methanol fuel cell, this is a variant of a Proton Exchange Membrane Fuel Cell, what it essentially means is that the MEA reforms the Methanol to Carbon Dioxide and Hydrogen without any external action required. It really is all clever stuff! Looking at the panel on the right hand side of the label, we can see that the “active area” of the fuel cell, that is to say the bit with the catalyst is 2.3cm x 2.3cm, about an inch square for those using Imperial.
The Nafion membrane itself is significantly larger, 5.5 x 5.5 cm square, or about 2 inches square.

We can see looking at the details below, that the Anode is coated with a mixture of Platinum and Ruthenium, 4.0 milligram per cm3 to be exact, whilst the Cathode is loaded with 2.0 milligram of Platinum. The Membrane has a built in Gas Diffusion Layer of carbon cloth.

Cotton Gloves

At all times when working with the MEA, you will need to wear cotton gloves. This is because the muck on your hands will greatly inhibit the function of the MEA.

Making the Band Aid Fuel Cell

Making the Band Aid Fuel Cell is a real walk in the park. All you need to do is be sure that you protect the MEA and handle it delicately, and try and ensure all surfaces remain clean.

First of all, you need to cut a rectangle of wire mesh. This should be a little narrower than the smallest dimension of the “wound pad” of your band aid, and longer than the longest dimension of your band aid. Cut another identical strip.

Cutting the Wire Mesh

Now, remove the protective covering from one Band aid, and place the first piece of wire mesh so that it sits just inside the “wound pad” of your Band Aid. The other end will protrude past the end of your Band Aid.

Laying the Wire Mesh on the First Band Aid

Now, remove the MEA from the bag carefully using cotton gloves.

Getting the MEA out of the Bag

You need to trim the MEA so that it is slightly bigger than the wound pad of your Band Aid, but so that there is still a generous border of Band Aid sticky to hold the assembly together. The MEA MUST overlap the wound pad.

Trimming the MEA to size

The next shot displays the MEA checked for size against a Band Aid. Note that “Anode” is marked on the MEA, you need to make a note of which side “Anode” appears the correct way round on, make a note of this and put a “+” on the Band Aid facing the MEA. You might want to use an overhead projector pen to do this.

Checking the MEA for Size (Remembering Orientation)

Next lay the MEA on the wire mesh, noting orientation. Ensure that the overlap of the MEA sticks to the border of Band Aid adhesive, you need to isolate each side of the MEA from each other using the Band Aid Adhesive as a barrier.

Laying the MEA on the Wire Mesh

Now take the other strip of Wire Mesh that you cut, and lay it up on the MEA so that the spare length of gauze protrudes from the opposite end.

Laying the final layer of wire mesh on top of the MEA

I found at this point that it was a good idea to bend the wire gauze back on the Band Aid corresponding to the side of the MEA the gauze was in contact with. This helped me to remember which piece of gauze was what electrode.

Using a scalpel to remove a square from the top layer of Band Aid

Now, use a scalpel to remove a 1cm square of the “pink” bit of band aid from the side that is in contact with the “Anode” side of the MEA.

The completed Band Aid Fuel Cell

Testing the Band Aid Fuel Cell

To test the fuel cell you will need some 3% Methanol solution. Again you can get this from Fuel cell store, unless you know a bit about chemistry or are friendly with a college lab technician.

To fuel the cell, you will need to introduce methanol solution to the patch of band aid you removed on one side. The wound patch will act as a reservoir for the fluid. Keep the other side of the fuel cell dry, oxygen will permeate through the breathable Band Aid.

Connect the electrodes protruding from either end of the Band Aid to a multimeter, do not expect big shakes first time round! DMFC fuel cells take time to “break in”.

The Band Aid Fuel Cell Connected to a Meter

I found that the voltage that my cell produced was improved by applying a little light pressure to the area either side of the methanol top up point. This is because the wire gauze makes better contact with the MEA.

The Band Aid Fuel Cell with Light Pressure Applied

Good luck and happy Band Aid Fuel Cell Building.

Shopping List

• Posh Fly Screen – Link.
• MEA – Link.
• Cotton Gloves – Link.

Gavin D. J. Harper is author of 50 Awesome Auto Projects for the Evil Genius, Build Your Own Car PC, 50 Model Rocket Projects for the Evil Genius by Mc Graw Hill and Solar Energy Projects for the Evil Genius. A book on Fuel Cells is in the pipeline.