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Fabric Bend Sensor

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Step 5: Closing the sensor

Picture of Closing the sensor
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Before closing the sensor you will want to cut out a piece of Velostat that is just a little bit smaller than your pieces of neoprene. This piece of Velostat will go in between your two conductive stitches. And this is what creates the pressure sensitive change in resistance. The Velostat lets more electricity through, the harder you press the two conductive layers together, with the Velostat in between. I'm not really sure exactly why this is, but I imagine it's because there are carbon particle in the Velostat that conduct electricity and the more pressure on them the closer they come together and the better they conduct or something similar (???).

So, place the piece of Velostat in between and sew the sensor together as shown in the pictures. Don't sew too tightly, otherwise you'll have an initial pressure which will make your sensor less sensitive.
 
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azdelslade4 years ago
hi, first off, thanks for the brilliant instructable! i made one of these with all the components you listed here, neoprent and actual velostat. i can get readings off of my multimeter fine and change an led with a battery fine, but when i hook it up to my lilypad, I only see changes between 1023 and 998, which is not much. I tried loosening up the stitches and using digital 5 as a power source instead of +, but it doesn't seem to help. Any suggestions? When I put my multimeter on 200k i get readings between 20 and 0.5. I tried adding 10k, 1M and 10M resistors, but that still didn't improve the sensitivity. I also tried adding another piece of velostat.
leisure12314 years ago
which kind of sensors do you choice?
Geemge05 years ago
Is the stretch fabric doubled over in this? Or is it simply one layered slice of it? Great guide btw.
Plusea (author)  Geemge05 years ago
the stretch fabric is neoprene. it is 1,5mm thick with jersey fused to each side (one side green, one side grey). so there is only one layer of neoprene for each side. does this answer your question?
chuckw5 years ago
Why does it look like the Velostat isn't sandwiched between the top and bottom layer in a few of those pictures? ..Chuck..