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The fifth challenge is disposable electrodes

A project log for uMyo - wearable EMG sensor with wet/dry electrodes

EMG sensors for controlling devices and PC with muscle commands

olya-gryOlya Gry 11/10/2022 at 20:310 Comments

According to our observations, existing EMG sensors often use disposable electrodes to receive a signal. We initially began to look for an alternative to them, and as you can see from past logs, we found it.  

But when we already debugged uMyo using dry connectors, it became interesting what kind of signal quality a gel electrode would give for comparison. And while we were looking for a way to check this, the idea came to make the possibility of a combined use, a kind of device with a hybrid attachment method. Because gel electrodes are still the classic way to receive a signal and perhaps some people will want to use it, and not the dry ones.  

To begin with, we had a hard time finding metal buttons of the right diameter for the 3.9 mm connector of standard medical electrodes. After, we tried to solder them to uMyo. It turned out to be easier than soldering the connectors to the uECG... 

Also, the distance between the connectors on the board is about 34 mm, so the diameter of the electrodes should be no more than 30 mm.  It wasn't easy, but we found 20x20mm square baby electrodes and used them for testing.  

Then we tested them - basically just attaching it to a hand over a particular muscle. Results turned out to be great - it was practically immune to noise and able to pick signal from a muscle that controls particular finger, while other fingers movement produced barely visible response.

Let's summarize - uMyo can now be used in two ways, depending on the required signal quality. Dry electrodes are quite suitable for all purposes - yet when high precision is necessary gel electrodes outperforms them, to the point that they can be used on muscles not functioning properly like in rehabilitation.

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