I recently purchased two Myomatrix 2.0 sensors. Both of them seem to be defective!!!
I am powering them with the Myoware power shield, placing the electrodes over the midline of the muscle belly and reading the ENV signal on an oscilliscope. The signal is a fluctuating noisy wave when the muscle is at rest and strong contractions don’t affect it. The ENV LED is also akways off when electrodes connected to muscle and constantly blinking when removed
Reading other posts on the forum, it looks like several other users describe a similar issue. It therefore seems that a defective batch of MyoWare 2.0 have been produced and sold. This is very frustrating as I am hesitant to order new ones by fear of once more receiving defective units.
Can SparkFun look into this and make sure no more defective units are being sold!?
Share a video of the behavior/hookup apparatus
Are you following our guide? https://learn.sparkfun.com/tutorials/ge … are-hookup Have you made any gain adjustments? Where is the REF placed, if used?
Please find the link to the video of the apparatus and the recorded signal here below:
https://drive.google.com/file/d/1Q46_8O … sp=sharing
I get the same result with the second sensor where the external reference electrode is used (after slicing the jumper).
Yes, I am following the guide and trying different gain adjustments does not solve the problem.
Most of it looks good, I actually think you are only seeing the initial increase and then it falls off because you’re only forcefully contracting for a split second, and relaxing the muscle for the most part while slightly contracting the elbow angle (which doesn’t use the midline/belly as much)
Re-try with the bicep/arm fully extended to set 0 point, then try flexing bicep against something with resistance (like your other arm, the table, etc) and see how that goes
I don’t understand your explanation. Why wouldn’t short strong muscle contractions be clearly visible in the EMG signal?
Here is a video of another EMG system clearly showing responses for biceps contractions (raw signal, same bandpass settings as for the raw signal in MyoWare):
https://drive.google.com/file/d/188BIlk … sp=sharing
Here is the same electrode configuration and muscle contractions showing the RAW signal from MyoWare 2.0:
https://drive.google.com/file/d/1vrVDgr … sp=sharing
Clearly there is something wrong with this device!
Was it purchased from us? If so head over to www.sparkfun.com/returns (contact vendor if purchased elsewhere) and we’ll get ya squared away
Ok, I’ll try to return them to the vendor and order 2 new ones. Let’s see if the new ones will function properly.
I tested the 2 newly ordered sensors (from a different vendor) and they are also defective! When measuring the raw signal all sensors show the same: a noisy wave that does not react to muscle contractions (as shown in the video above).
This is now 4 sensors ordered from 2 different vendors that are defective! There is something clearly wrong with these devices.
This has been one big waste of time and money.
I am also having problems with the Myoware 2.0 muscle sensor. The sensor works fine when I have the LED light shield on it but as soon as I hook it up to an oscilliscope or computer it stops working. Any ideas?
You have to use the external REF probe if tying these to something with a separate GND