DIY Electromyography

Electromyography (EMG) is the measurement of electrical activity in muscles and is the key component to mechatronic prosthetic devices, particularly prosthetic arms and hands. Commercially availible EMG devices can be expensive costing several hundred dollars and EMG technology in existing prosthetic devices are often proprietary. The DIY Myoelectric board is only a handful of components, under $30 dollars and can quickly get you up and running doing basic sensing and control with voluntary muscle contractions.

The DIY Myoelectric board is a single-sided board with through-hole components with the idea that this will be easier to build. In the works is a smaller double-sided board with mostly SMT components that might be slightly more difficult to build but be more compact. The circuit is designed around the Burr-Brown INA114 instrumentation amplifier with an option for adjustable gain. There is also an on board quad op amp to filter the output or use in conjunction with a transistor to get a 5 volt output for a microcontroller.

The other critical componet to the DIY Myoelectric board are the Ag/Ag chloride electrodes. These are the standard electrodes that get used in hospitals for doing ECG, EMG and other bioelectric signals. Here are a couple sources to buy them fairly cheap Danlee Medical Products and GRASS Technologies.

If you want something more sophisticated check out the Open Prosthetics Project. It's an open source collaboration between users, designers and engineers with the goal of producing useful innovations in the field of prosthetics and freely sharing the designs. They're developing an open source Myoelectric Signal Processor which will be quite sophisticated; 16 channels, digital signaling processing and lots of modularity.