EMG Sensors: Advantages and Disadvantages

This page explores the advantages and disadvantages of EMG sensors, along with a basic introduction to their function.

Introduction

During sustained muscle contraction, multiple motor units fire repetitively. The force of muscle contraction is related to the number of motor units active within the muscle. An EMG recording during muscle contraction appears as a burst of spike-like indicators. The duration of this burst corresponds to the duration of the muscle contraction. The strength of skeletal muscle contraction is directly proportional to the amount of electrical activity in the muscle.

What is an EMG Sensor?

An EMG sensor provides an electromyogram. EMG measures the electrical activity of muscle groups both at rest and during contraction. This sensor measures the filtered and rectified electrical activity of a muscle. Typical features of an EMG sensor include adjustable gain, a small form factor, and full integrability.

The EMG is used as a diagnostic tool to identify neuromuscular diseases, assess lower back pain, and in kinesiology. EMG signals are used in many scientific and biomedical applications, including control signals for prosthetic devices. It typically consists of three electrodes connected as shown in the figure above.

EMG sensor modules are commercially available.

Benefits/Advantages of EMG Sensors

The following are the benefits or advantages of EMG sensors:

• Quick and Easy Application: EMG sensors using surface electrodes are very quick and easy to apply.
• No Medical Supervision Required: Their use does not require medical supervision or certification.
• Minimal Discomfort: They offer minimal discomfort to the subject.
• Fine-Wire Electrodes: Fine wire electrodes can record single muscle activity and provide access to deep musculature.
• Extremely Sensitive: They are extremely sensitive to electrical activity.
• Continuous and Quantitative Data: EMG provides continuous and quantitative data. Multi-channel EMG can identify muscular bottlenecks.
• Early Fatigue Detection: EMG data allows for the detection of muscle fatigue at early stages.

Drawbacks/Disadvantages of EMG Sensors

The following are the drawbacks or disadvantages of EMG sensors:

• Superficial Muscles Only: Primarily useful for superficial muscles only.
• No Standard Electrode Placement: There is no universally standardized electrode placement protocol.
• Potential to Affect Movement: The sensor may affect the natural movement patterns of the subject.
• Limited Detection Area: The detection area may not be fully representative of the entire muscle.
• Cross-Talk: Cross-talk from other muscles can be a concern.
• Limitations with Dynamic Activity: Limitations exist when recording dynamic muscle activity.