Toward Soft Wearable Strain Sensors for Muscle Activity Monitoring.

Area of Science:

• Biomedical Engineering
• Sports Science
• Rehabilitation Technology

Background:

• Skeletal muscle force capacity is crucial for assessing musculoskeletal health, athletic performance, and diagnosing neurological conditions.
• Traditional strength evaluation methods are limited by technical requirements, discrete measurements, and controlled environments.
• Continuous, non-restrictive muscle monitoring is needed for richer datasets and improved health evaluations.

Purpose of the Study:

• To introduce and validate wearable, ultra-sensitive soft strain sensors for continuous muscle force and deformation tracking.
• To assess the sensors' ability to monitor muscle contractions and fatigue during various protocols.
• To evaluate the system's effectiveness in estimating muscle fatigue-induced torque reduction.

Main Methods:

• Development and application of wearable, ultra-sensitive soft strain sensors.
• Testing sensor sensitivity during isometric muscle contractions.
• Monitoring changes in peak torque during isokinetic fatiguing protocols for knee extensors.

Main Results:

• Sensors demonstrated sensitivity to isometric contractions.
• The system accurately tracked peak torque reduction during muscle fatigue.
• Estimated peak joint torque reduction showed a mean Normalized Root Mean Square Error (NRMSE) of 0.15±0.03.

Conclusions:

• Wearable soft strain sensors provide a promising, non-invasive method for continuous muscle strength and fatigue monitoring.
• This technology can enhance athletic training, patient recovery assessment, and the diagnosis of neuromuscular disorders.
• The system offers a more flexible and data-rich alternative to traditional strength evaluation hardware.