A Piezoresistive Sensor to Measure Muscle Contraction and Mechanomyography.

Area of Science:

• Biomedical Engineering
• Biomechanics
• Sensor Technology

Background:

• Electromyography (EMG) is standard for muscle activity measurement but has limitations.
• Alternative methods for muscle activity monitoring are being explored.
• Mechanical variations during muscle contraction offer a potential measurement avenue.

Purpose of the Study:

• To present a new, simple, non-invasive sensor for measuring muscle contraction using a force-sensitive resistor (FSR).
• To evaluate the sensor's ability to detect both gross muscle force and mechanomyograms (MMG).
• To assess the sensor's performance as an alternative to EMG in biomedical applications.

Main Methods:

• Developed a non-invasive sensor using a force-sensitive resistor (FSR) housed in a rigid dome.
• Applied FSR conditioning techniques to mitigate creep and ensure a voltage output proportional to force.
• Recorded simultaneous data from the FSR sensor and traditional EMG.
• Performed preliminary validation tests using healthy subjects for prosthesis control.

Main Results:

• The FSR sensor successfully measured muscle contraction force and mechanomyograms (MMG).
• Appropriate FSR conditioning effectively reduced output drift.
• High correlation (Pearson's r > 0.9) was observed between FSR output and EMG linear envelope.
• The sensor demonstrated comparable performance to EMG in controlling a hand prosthesis.

Conclusions:

• The FSR-based sensor is a promising non-invasive tool for measuring muscle activity.
• It can detect both force and MMG signals, offering a richer dataset than EMG alone.
• The sensor shows potential as a practical alternative to EMG for applications like prosthesis control.