Electromyograph (EMG)

The Electromyograph or EMG signal is associated with the activation of thousands of tiny muscle strands making up a muscle or muscle group. This signal generally takes the form of many high frequency sinusoids summed together. The EMG is usually measured using a skin surface electrode placed at either end of the axis of motion of the muscle. The size of the EMG response depends on a number of factors, including the distance between the electrodes as well as the size of the muscle under examination. Certain facial muscle groups have been found to have considerable psycho-physiological significance in humans.

There are a number of ways that the EMG signal can be handled. It is desirable at times to record the raw or unprocessed EMG signal for later analysis. However, this method requires an extremely high sample rate, with a corresponding increase in the amount of memory required in order record the EMG signal for a reasonable time. However, such an approach is necessary if the desired post-processing algorithm (spectral response for example) requires the summed sinusoidal data and the higher sample rate requirement as a result.

If the magnitude of the EMG response for a particular muscle is all that is required, precision rectification can be applied to the amplified EMG signal. The precision rectification process supplies just the positive envelope of the EMG signal, which can then be recorded. This approach is sometimes called a contour follower in the research literature. This approach benefits by requiring a much slower sample rate, and so enjoys extended recording time, when compared to recording the raw EMG signal.

And, of course, We recommend the use of our Fetrodes for all EMG signal conditioning and recording systems.

If you have your own data collection system, we can recommend our 2283FT or 2283FTi Fetrode signal conditioners. Let us know your target sample rate, and we will characterize the amplifier for your requirements. We can also address a multi-channel bank of Fetrode amplifiers if your research will deal with recording from multiple muscles.

Our Biolog systems can also support a number of EMG channels both with and without the Precision Rectification included. The SC2000 Simple Scope PC based data collection system can also be configured for Fetrode EMG. And we have included precision rectified EMG on a Multi-Subject Data Collection System installation.

If you still have questions, or if you don't see what you need, drop us a line, and we will see how we can help you!

Product Families:
Bioamps/signal conditioners
Ambulatory data loggers
Hot Flash Recording
BAERCOM™ hearing tester
PC-based instruments
Multi-subject systems
Test instruments