I need the customized flex sensors

Forum 2005-2010 (read only) Hardware Interfacing
1

Dear everyone:

The requirement in my minds is that the flex sensors has a resistance of 0 ohms to 2K ohms and increase while it is bent.
But the general product to that is so big and casual. Also, part of them decreases while it is bent and that is not fit for what I need.

Do someone know who can make it for me? I appreciate that.
Thanks for your reply. :slight_smile:

2

well you can fix it decreasing when bent with this:

sensorVal = map(sensorVal, sensorMin, sensorMax, newsensorMax, newsensorMin);
3

Also, part of them decreases while it is bent and that is not fit for what I need.

Not too sure what you want. If you bend anything the inner curve compresses and the outer curve increases.
If it is just that you want the resistance reading to go "the other way" when bent simply subtract it from a constant, 1023 is a good one to choose as that is the full scale reading from the arduino.

4

Regarding "big and casual" (interesting translation there):

Have you thought about building your own flex sensors? I can give you a couple of ideas:

  1. http://www.instructables.com/id/Make-Conductive-Glue-and-Glue-a-Circuit/

If you check out the instructable, as well as his web page on the conductive glue, he talks about how it changes resistance when bent; perhaps you can use this information to make your own bend sensors that are smaller/thinner?

  1. Use cheap plastic optical fiber, or even thin, clear PVC tubing (PVC aquarium air-line tubing will work, thinner tubing is available as well - check into medical supply for drip-line and oxygen mask tubing); attach an LED on one end, and an LDR or photo-transistor on the other end. With the optical fiber, you will want to use a small razor knife to nick it perpendicularly along the length (spaced regularly). When you bend the sensor, less light is let through, and this change can be detected.

Note that in the case of optical fiber, this will only work in one direction (whereas with the PVC tubing, it can be flexed in any direction and still give you a change in reading). The optical fiber method was used by VPL back in the 1990's for their DataGlove system, although they used high-quality glass fibers, and nicked the cladding; the principle is the same, though, and should work (I am pretty sure the patents on this kind of bend sensor are expired - IIRC, the patent was awarded in 1987, and was last owned, I think, by Thompson?)...

Hope this helps you or someone else in some manner!

:slight_smile:

5

You know how professional you are in this issue that you completely comment. I really appreciate that.

I will give it a try that you offer to me.
Again, you all beyond the scope of the most hobbyists.

Thanks!