MyoWare Muscle Sensor allows you to control your projects with your muscles. Pair the MyoWare with some Muscle Sensor Surface EMG Electrodes and a microcontroller (ie. Raspberry Pi, Arduino, or Beagle Bone Black) and you are ready to create a DIY low-cost version of an EMG or an electromyography.
According to Wikipedia, electromyography is an electrodiagnostic medicine technique for evaluating and recording the electrical activity produced by skeletal muscles. Use these sensors in prosthetics, robotics, and so much more. Once you attach the sensor to a large muscle (like your bicep) you can flex and measure the signal spike as an analog voltage.
These MyoWare Muscle Sensors are designed to be used by hobbyists, backyard tinkerers, and students alike. Check the datasheet for more information and both setup configurations as well as setup instructions.
Note: Electrodes and Arduino (or other analog-reading microcontroller) not included, you'll need both to get readings out of the Myoware!
Adafruit Product Page: https://www.adafruit.com/products/2699