Muscle Sensor v3

Granted, using our muscles to control things is the way that most of us are accustomed to doing it. We push buttons, pull levers, move joysticks… but what if we could take the buttons, levers and joysticks out of the equation? That’s right, take the electrical signal straight from the muscle and put it into your device. Thanks to shrinking amplifier technology, we can now do exactly that!

Measuring muscle activity by detecting its electric potential, referred to as electromyography (EMG), has traditionally been used for medical research. However, with the advent of ever shrinking yet more powerful microcontrollers and integrated circuits, EMG circuits and sensors have found their way into all kinds of control systems.

This sensor will measure the filtered and rectified electrical activity of a muscle; outputting 0-Vs Volts depending the amount of activity in the selected muscle, where Vs signifies the voltage of the power source. It’s that easy: stick on a few electrodes (not included), read the voltage out and flex some muscles!

Note: The Muscle Sensor v3 no longer includes biomedical sensor pads and cables as its previous version did. Both the pads and cable can be found in the Recommended Products section below to be purchased separately.

  • Small Form Factor
  • Specially Designed For Microcontrollers
  • Adjustable Gain
  • 3.5mm Connector
  • Breadboard Compatible
  • Power supply voltage: min. +-3.5V
  • 1.0" x 1.0"

Customer Comments

  • Hello! I have been trying to model the response of the sensor using the schematic provided, and have found that the inverting-active low pass filter circuit has a cutoff frequency of 2Hz. are the resistor and capacitor values of the schematic accurate? or did I screw up badly somewhere in my calculations D: appreciate if someone can help me, thanks!

    • The 2Hz cutoff is the frequency for the integration circuit. The circuit layout is similar to a LPF but since the signal has been rectified at that point, it acts as an integrator. http://www.electronics-tutorials.ws/opamp/opamp_6.html

  • Admittedly, I’m a bit of a novice at hooking up electronics. What’s the story with the 2 9V batteries? Can that be skipped and this connected through one power pin to the microcontroller?

    • You can use other batteries besides two 9Vs. That is just a quick and simple example to help people not familiar with dual supply powered sensors. Unfortunately, you cannot power the V3 with a single supply source like a microcontroller. You need a positive voltage and a negative voltage. Keep in mind that a negative voltage is not the same as ground.

      That being said, the new MyoWare sensor (which will be soon available on Sparkfun) only requires a single supply power source and can be powered with a microcontroller directly. You can check it out here: https://www.kickstarter.com/projects/312488939/myowaretm-harness-the-power-of-your-muscle-signals

  • Managed to use them to control me exoskeleton https://www.youtube.com/watch?v=A91GoxHYcBM&feature=youtu.be

    They are excellent, although i recommend using conducting fabric with them as the pads only really have a couple of uses.

  • What is the maximum sampling rate of these kits? Are they limited in anyway?

    • It’s an analog sensor so sampling rate doesn’t really apply. It would depend on the ADC/microcontroller/DAQ that you use to measure it.

  • There is one output signal, than y the arduino code is reading through all the 6 analog pins and sending to serial port??

    • The Arduino code is meant to be run along side the Processing code. It outputs all six pins so you can connect up to 6 sensors and view their output graphically via Processing.

  • Has anyone had noise issues with this sensor? If so did you just do a running average of the data?

  • Can I detect an eye blink with this sensor? Also if the pads get soiled with sweat, dirt etc from the skin is there some way to wash and reuse them?

    • The pads are a single use item. Ideally you want to protect them from water while wearing them. Sweat (and water) will slowly degrade the adhesive, especially if the skin under the pad is moving.

      Ideally, clean the skin with an alcohol pad before applying the pad. Also, if there’s any hair under the button you won’t get a signal (or a very poor one). THAT means, if you want a sensor in a particular spot, you may have to shave it first.

    • The biomedical pads are probably too big for measuring eye muscles but the sensor should be able to pick them up if appropriate pads are used.

  • Hi very glad to have this item, is very helpful and very practical and easy to use. I have only one issu is that I need to do much efforce my muscle to get the signals and move servomotor, this is my question How can i do to filter the signals and put less effort for this sensor can works with minimum effort muscles?

    • Are you driving the servomotor directly with the sensor? Usually this is done with a servo driver or microcontroller. If using a servo driver or microcontroller, you’d simply need to map the input values to higher values before sending it to the servo. You could also alternatively increase the sensor gain via the potentiometer marked as Gain in the middle of the board.

    • Do you want to apply a matrix, to make, say 1-5v output read as 1 to 1000 units? or are you asking to make the sensor more sensitive? I am curious about the sensitivity. I am also wondering what the difference is between this one and its previous model.

      • This is actually the same sensor board as before. The difference is that the sensor board was packaged as a kit but is now sold separately.

Customer Reviews

4.7 out of 5

Based on 6 ratings:

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2 of 2 found this helpful:

works perfrctly

Once everything was wired up correctly I had zero problems with this product. It is a great and accurate sensor!

2 of 2 found this helpful:

Nice company

Nice and efficient company. Received the items on time. Prices are a little bit expansive Nice product

1 of 2 found this helpful:

Is Excellent but...

Hey Sparkfun’s People, your product and your service is excellent but I need more sensor and you dont have any more in this moment, please help me with this sensors, Its for my final project! Regards!

Great sensor :)

It does everything it´s supposed to do.

Don't release the magic smoke

If your like me, you like to read pictures first and words later (if ever) when figuring out electronics. Well make sure you hook up your 9V batteries correctly. The picture of the batteries isn’t super clear and you’ll release the magic smoke. Other than that, this board is is great to connect to a micro-controller ADC input.

Easy to set up, easy to use.

Very easy to set up and use. It did not come with the headers that need to be soldered though so make sure you have those available. A few shortcomings (though minor ones). 1) There’s no way to access the output signal before smoothing / rectifying (not necessarily the raw signal), just after the first stage amplification. 2) The gain potentiometer is a continuous one. So one is never quite sure what the gain value is.