Step 12: Circuits

If you've gotten to this point, your Soft-Circuit position sensing glove is in working order so now the fun can begin!

Flex sensors only change resistance with respects to bend angle. You're going to have to build a circuit to convert this resistance change into a voltage to make it useful.

Here is the Spectra Symbol Flex Sensor spec sheet. They describe a couple different circuits you can use for different applications. Basically, the simplest one is to use it as a variable resistor in a voltage divider (with an op amp impedance buffer tagged on at the end of it). 

We design our circuits and protoboards in Eagle. This is a great way to plan out your circuit elements' positions before hand. We've posted pictures of the Eagle schematic and board layout files below. (The pictures look pretty small but if you click the "i" button when you hover over the image, you'll go to another page where you can download the much larger original images.)

Note: The circuit we built for the demo is for applications where you want to monitor the angle of bend of each finger. However, the circuit you need will change depending on your intended application for the glove. Some examples of circuits for other applications can be found in the Spectra Symbol datasheet as well.

Basically the circuit works like this.
5V input voltage --> inverting amplifier with a gain of -1 ----> voltage divider ---> inverting amplifier with a gain of -2.5 ---> MCU analog input pins.

Well eventually get around to posting an instructable detailing how to build the one we used in the demo. Until then, feel free to ask questions.
Great project! Do you think this glove can distinguish between size of spherical balls?
I think the male headers you recommend are a bit too short. (contact mating length of 5mm) After playing around with a variety of lengths, I recommend instead going for an 8mm contact mating length. <br> <br>http://www.digikey.com/product-search/en?WT.z_header=search_go&amp;lang=en&amp;site=us&amp;keywords=609-3510-ND <br> <br>Otherwise, thanks a lot for the parts list. It makes for much sturdier and cleaner-looking result than my original approach to putting together the flex sensors.
Hello, this is very interesting and innovative. Please if it isn't too much trouble, do you mind explaining the circuit in the pcb design above. I am just a beginner in electronics and I would like to understand it better. I hope to hear back soon.
wow this type of work is what ive been dreaming off all my life ! I mod everything i get my hands on like my PS360 :) i had an idea for this 10 years ago but didn't know where to start thank u soo much now Im gonna make this type of glove work for my 360 :)<br>
hey,me and you got the same last name Kaminski
Cool! You can use this in an Iorn Man style. Use it to drag stuff across your computer! =D
This is awesome! would it work to make a robot like the ones on Avatar?
Sure. By the way, if you're interested in that technology, you should google the Raytheon/Sarcos robotic exoskeleton or the UC Berkeley exoskeleton called BLEEX.
Hey! Nice instructable!! Is there a way to use it to control my HI-FI system?
I'm sure it could. What would you like it to do?
COOL! with some reprogramming, you can make a mouse out of this!, then you just bend your fingers instead of moving the mouse. Can it be done wireless?
Sure it could be done wirelessly. To do this, along with the circuit described in the instructable, you would need to tack on an analog to digital converter circuit and link that with a wi-fi or bluetooth transmitter (or simply integrate an arduino MCU with bluetooth capabilities into the glove).
I've been thinking making an 'ExoGlove' sorta thing for ages...never though of using a soft circuit glove though. <br>So how long do you think it will take to get the pneumatics working?
The pneumatics is the current phase of the project that we're working on. Most of the system has been built, we really just need to raise some extra capital to finish the project. <br><br>I'll post some more up-to-date photos on AdvancerTechnologies.com for you to check out.<br>
How strong is it going to be?
Will you be making an instructable detailing the interface circuit, too?
Hey Jeff, I'll probably get around to posting an instructable detailing how to make the circuit. In the meantime, I'll throw up some pictures of the Eagle schematic and board layout.<br><br>I didn't really want to go into too much detail on the circuit in this instructable because the circuit you need will change depending on your intended application for the glove. The circuit I used is good for tracking the bend of each finger. However, if you wanted to have each finger act as a switch triggering some event, a different circuit would be better suited for that application.
woops sorry i was actually going to use prusea... or maybe plusea's bend sensors i see you made a note to that
wow seeing this reminded me of a project i wanted to do in the 8th grade it was almost exactly like this i mean exactly! but i was going to make a program that would make it readable by a robotic hand...now the hand was much more complicated. sadly my mom thought school was more &quot;constructive&quot; nice ible by the way
This iz confusing- but it seems really cool!
Hi cillianwall, thanks for the feedback. Was there a particular section that was confusing?
Hey this looks Really cool, but I think she means that if your not really into electronics then this could look pretty daunting!! but theirs not much you can do about that!! ;) lol! C.B.<br>

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Bio: Brian Kaminski Owner - Advancer Technologies Brian graduated from North Carolina State University with a BS in Biomedical Engineering with a concentration in Biomechanics in May ... More »
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