Testing Flex Sensors

Now that summer has started and spring classes have ended, I’ve had more time to work and be in the lab. For the past two weeks, I’ve been soldering EL wire and testing sensors. I met with Katie to talk about summer plans two weeks ago and we decided that we needed to get the prototype done by the end of summer. We also want to be able to submit another paper and if we have time, do an interface for the physical therapist.

I spent the first week soldering the end of cut EL wires from the part that Miranda made. This way, it can be hooked up and lit from the circuit. It was a lot easier soldering the wire this time than last time. However, I messed up soldering the first time and soldered the wrong ends to each other. I fixed it now and tested it so that they all light up.

I also created a simple Arduino circuit to test the flex sensor. Here’s a picture of the circuit I made:

It didn’t work at first and I looked up tutorials online and couldn’t figure it out. Finally, after asking Swamy, I realize that the resister I was using was too high. After swapping that out, it worked fine. I placed it on my knee and tested it around 5 times bending my knee 10 times in each trial. We did this to see how accurate of a reading we could get. From the graphs I made, it doesn’t actually look too bad, but we’ll see.

Swamy also gave me this paper to read about placing two EL wires together to measure two bends and obtain a more accurate reading. I soldered some pins to the end of the EL wire and put heat shrink on them to make the ends sturdier. Then I made a new circuit and tested out the two EL wires placed back to back. I have all the data for it in an excel file now so we just have to examine it.

I also need to test a bend sensor. Another member of the lab, Halley, created a flexible bend sensor made from conductive string. I still need to get this and test it out to see how accurate this type of bend sensor is.

This week, a lot of members of the lab were at the Pervasive Health Conference, so it was pretty quiet. I’ll meet up with Swamy again next week, when he comes back, to discuss the readings and see what we can do next. Miranda also comes back next week so we can get started on putting the prototype together.