Emg Muscle Sensor v1.3

EMG Sensor, also known as electromyography sensor is one that measures small electrical signals generated by your muscles when you move them!

• This includes lifting your arm up, clenching your fist, or even the simplest of movements like moving a finger!

Technical details

If you would like to further understand the technical side of things, here’s how your muscles move and its relationship with ECG:

• The whole process starts off in your brain
• Neural activity in the motor cortex (part of your brain) signals to the spinal cord
• The signal is then conveyed to the muscle part via motor neurons
• Motor neurons innervate the muscle directly, causing the release of Calcium ions within the muscle and ultimately creating a mechanical change
• This mechanical change involves depolarization (change in electromechanical gradient), which is then detected by EMG for measurement

What are the types of EMG sensors?

Now that we’ve had a better understanding of the definition of EMG, we’ll now take a look at the two types of EMG sensors!

sEMG sensors (surface electrodes)

• The “S” refers to the surface, where this type of EMG sensor takes measurements by placing surface EMG electrodes on your skin
• Uses Non-invasive technology, making this EMG sensor type not painful
• Commonly applicable in clinics and sports health
• Limitations: Though is a simple and easy way of EMG measurement, it’s restricted to superficial muscles and dependent on other variables such as the weight of patients, etc.

Intramuscular EMG

• Intramuscular EMG takes measurement through an inserting a monopolar needle electrode through your skin and into the muscle tissue
• A common way of EMG sensing
• A perfectly safe option, though it may cause discomfort when the needle electrodes are inserted and muscle soreness afterward
• Limitations: Possible contamination of deeper muscle recording as the needle shaft is exposed

How does EMG sensor work?

Both types of EMG differs from the sensor placement, though its procedures share certain similarities. Here’s the illustration of how each EMG sensor works!

This is how a surface EMG sensor works:

• The process begins with EMG sensor placement; where it’s placed in the innervation zone of both tendons for better detection quality (Picture 1)
• Electrodes begin to detect electrical activity generated by muscle movement/contraction
• Electrical activity detected is then displayed via the form of waves on a monitor (also known as an oscilloscope)

How an intramuscular EMG work:

• The process begins by inserting a sterile needle (monopolar needle electrode) into the muscle itself
• Electrodes begin to detect electrical activity generated by muscle movement/contraction
  • An audio amplifier may be attached for evaluation of appearance and sound
• The electrical activity from your working muscle is measured and displayed on the monitor

Note: Both EMG sensing sensor procedures should end up with either normal or abnormal results:

• Normal results:
  • Muscle tissue at rest should be electrically inactive with no waveforms
  • There should be varying rates and amplitudes spotted on the data when the muscle is fully contracted
• Abnormal results:
  • Unusual data collected
  • May result from disorders of muscle, nerves, etc.

Overall, the stronger the muscle contraction = the higher the number of activated muscles. Hence, a higher recorded voltage amplitude.