Flexing, Sensing, Depressing

For the past few days, I have been working on a new project. The idea was to use 10 flex sensors and gloves to create a virtual reality system, or to create a sign language translator. It seems like it will be easy to code once I have all the components.

Flex sensors, or bend sensors, are “bend-sensitive” resistors, whose resistance changes when they are bent in a particular direction, when manufactured in a specific way. When manufactured in a different way, they change resistance on application of pressure as well, so they can be used as pressure sensitive resistors.The concept is quite old in itself, since Nintendo has been using it in its PowerGloves since 2003. However, using flex sensors in hobby electronics is relatively new, and interesting. I was able to think of several applications for the sensors, especially if I outfitted all ten fingers with them.

The problem is, they are prohibitively expensive. They are quite costly abroad, but more so in India. They cost nearly 600 rupees each! That would make it extremely expensive to use ten for both hands. I decided to build my own.

I found a few websites which detailed a simple method to make one, which would take only 5 minutes if I had all the parts. A certain YouTube video said I needed copper tape/foil, tape, plastic and paper. This seemed the most basic of all the DIY online tutorials, so I set out to get parts.

I found it extremely hard to find the copper tape in my locality. I asked at nearly 20 hardware/electronics/stationery stores, and none of them stocked any copper. I tried to make do with aluminium foil, since it was a good conductor of electricity as well. That didn’t work either.

Finally, I was able to find a small copper piece at home, and I tried making the flex sensor from the YouTube video. It didn’t work. Anyway, the concept he used didn’t make sense. It seemed too good to be true.

I couldn’t find any other websites using the same basic materials, so I went through other online tutorials. Many of them used conductive foam of the brand name Velostat, and conductive thread for the outer electrodes. 

I went on the same wild goose chase across HSR Layout, in an attempt to find either of these materials. I was unsuccessful again. 😦

I found them online, but I was taken aback by the cost. They were only available from a select few websites, most had one of them out of stock, and they charged nearly 15% of the price as delivery charges.

I considered making my own conductive foam, since the thread could easily be replaced by a sheet of aluminium/copper. I found that the conductive foam available abroad was a special plastic, which was impregnated with graphite particles, and that was what gave it its conductivity.

I wondered how I could thoroughly fill the foam (sponge) I had at home with graphite to make it conduct electricity. I reasoned that since graphite conducts, a mixture of graphite and oil should also conduct. Sadly, it doesn’t. 😦

I need to know how to make conducting foam. Any ideas? Comment!


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