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Help Building biofeedback for muscle sensor / EMG with arduino

Discussion in 'Sensors and Actuators' started by stregoi, Nov 28, 2015.

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  1. stregoi

    stregoi

    5
    0
    Jun 13, 2014
    Hi hope someone can help me achieving this build, i am a newbee in electronics.

    I am working with a research project in my hospital department, where i have to monitor the back muscle activity in scoliosis patients.
    I have to record the EMG activity 4 different places ( 4 electrodes/channels), for 24h for like a whole week.

    I have in mind to use an Arduino ( as small as possible ), some electrodes, and somekind of external storage, an SD card maybe.

    i have been looking around in the internet but almost all projects involving EMG sensors are single channel and not storing in a card.

    So please any advice on how i can approach the project ?, what will i need and eventually some suggestions about what i am intending to do.

    Any help will be appreciated.
     
  2. stregoi

    stregoi

    5
    0
    Jun 13, 2014
    By the way i am planning to use Myoware as EMG sensor
    [​IMG]

    and this what i came with so far :

    [​IMG]
     
    Last edited: Nov 28, 2015
  3. Anon_LG

    Anon_LG

    453
    117
    Jun 24, 2014
    Your diagram, though crude, looks basically functional. The sensors will need connecting in parallel as you have correctly identified. I am unsure what is going on with the box labelled SD card. I would suggest that an SD is not to be used, easier instead to write to the AVR's internal EEPROM, the data may then be retrieved later at the press of a momentary switch and displayed on the handy Arduino terminal. Writing to the EEPROM and later reading to display on the terminal would be far easier to achieve.

    Ensure that you read the documentation thoroughly. From what I have read the sensors are very convenient with rectified and smoothed signal out. What kind of frequency are you looking at? You will need to poll the analogue read regularly along with writing to the EEPROM. Additionally, the AVR's have limited EEPROM, both storage accuracy and storage quantity must be considered.

    I hope this helps,
     
  4. pwdixon

    pwdixon

    52
    0
    Oct 14, 2012
    Looks ok and you can get some pretty small arduino boards. If you expect to record data for 7 days 24/7 then you will probably need to use something like an sd card and you will need to look at a pretty big battery as I assume the patient will be mobile.

    There's no info in the datasheet on the frequency of the data changes but I would expect the data to be changing quite rapidly so recording with enough data at what might be high data rates could be a challenge that might be a bridge too far for an arduino. You'd need to do some testing to find out what the resolution and data rates.

    This not going to be cheap creature as I see these sensors are about £30 each.

    You will probably also need to look at the mounting arrangement of the sensors as I doubt they are capable of staying put for a whole week without some additional mechanics. Also the sensor itself is not packaged suitably to stand up to the rigours of everyday life, washing, sweating etc. I'd imagine that traditional sensor leads wouldn't be quite as convenient as these lumps of electronics attached to a patient though.
     
  5. Anon_LG

    Anon_LG

    453
    117
    Jun 24, 2014
    Not necessarily. Polling may be infrequent, requiring only little storage. I am unsure of the skill level of the OP and I think that writing to an SD card may be a little complex for them, they are in the medical profession, not electronics engineering.

    If you cared to study the data sheet, you would find that the output is analogue continuous. As I have mentioned above, this may be polled. Data rates do not come in to the matter of output, only on the input.

    stregoi, you may require external storage, however an SD card that utilises USB protocol may not be the best solution. A parallel input external EEPROM or even MRAM chip is the best solution in my view. Of course, the polling may be infrequent and extra storage on top of internal EEPROM may not be required.

    I hope this helps,
     
  6. pwdixon

    pwdixon

    52
    0
    Oct 14, 2012
    I assumed that looking at the sensor output that any useful info would require at least a series of fairly high sample rate data to be acquired though I agree sample series' could be saved periodically to reduce the quantity of data overall.

    Why would using an SD card require USB protocols? The arduino comes with a library for SD card use that is pretty easy to use even for a non-electronics engineer and it has nothing to do with USB.

    Wouldn't a parallel input external device require lots more electronics knowledge? Also, wouldn't an external device other than say a USB stick have significantly less memory capability than almost any SD card available now?
     
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