Conductive Glue And Conductive Thread: Make an LED Display and Fabric Circuit That Rolls Up.

Step 4 Make Conductive Foam and Switches

While these components were not used in this project, I thought some might be interested in how this can be done.

Make Conductive Polyurethane Foam
You can make open cell Polyurethane foam--the kind used for foam paint brushes and pillows and cushions--conductive by coating it with conductive mix #1 (See Pic 10). Use a metal spatula or a plastic spreader such as an old credit card and apply glue on the surface of the foam and quickly spread it thin by compressing the foam with the spreader. If you wait too long the solvents will start to dissolve the foam. Flip the foam over and do it again adding more glue as necessary. Make sure the glue is evenly distributed and worked as thin as you can. Make a larger piece of foam than you will need as some of it may have too much glue and end up stiff as it dries. After it has dried, cut out the softest most flexible part to use for your switch button.

Make Conductive Polyester Foam.
Polyester foam, the white fibered kind also used for pillows and cushions, can also be made conductive using the method above.


Make Foam Switches and Foam Pressure Sensors
Pic 11a shows how you can make two conductive pads with conductive thread embedded, using conductive glue #4. Then you can glue a conductive foam square button (3/4" x3/4") to one of the pads to create a pressure sensitive switch (pic 11b). The resistance of the switch I made varies with pressure from about 5K ohms to 100K ohms. With no pressure, the resistance is even higher. So it can be used as a switch or as a pressure sensor.


Make a Membrane Switch
A very thin, nearly transparent membrane switch can be made (see pic 12 and 12B) using nylon or polyester netting fabric. See step 6 on how to make the conductive fabric. The netting I used had about 24 squares per inch. You can then glue two small squares of the fabric to glass or another fabric using glue #4 on the edges with conductive thread embedded. Leave a small gap between the squares. Glue another square of the conductive fabric over the two squares using a clear contact cement like Welder. If you are gluing onto fabric, you can put an insulating netting with four to eight squares per inch underneath the top conductive fabric to keep it from turning on if the base fabric is bent.

The membrane switch shown has an open resistance of about 1 meg ohms and a closed resistance of 13k ohms. Certainly low enough to input into a microprocessor or other digital circuit.

Comments

[rmohamed1]

hi..cool idea..neway, whats the conductive mix made from? and what type of glue did u use?

thanks

[dgraham-2]

I ask because that question is clearly answered, and on THIS page lol.

[dgraham-2]

Did you read the entire article? :P