Shoulder Angle Measurement by Optimized Strain Sensor Placement on Flexible Printed Circuit.

Area of Science:

• Biomechanics and Wearable Technology
• Sports Science and Engineering

Background:

• Accurate measurement of scapular motion is crucial for understanding upper limb biomechanics.
• Existing methods for motion capture can be cumbersome or lack integration into sportswear.
• Flexible printed circuits offer potential for novel wearable sensor integration.

Purpose of the Study:

• To develop a novel wearable sensor prototype for scapular motion analysis.
• To optimize sensor placement on sportswear for enhanced measurement accuracy.
• To evaluate the accuracy of scapular motion measurement using different sensor configurations.

Main Methods:

• A new wearable device featuring a flexible printed circuit with 30 strain sensors was developed using screen printing technology.
• Sensors were strategically placed on sportswear covering the clavicle, shoulder, and scapula regions.
• Four subjects performed standardized basic and combined upper limb motion tasks while wearing the prototype.

Main Results:

• Seven different sensor arrangement models were evaluated based on combinations of clavicle, shoulder, and scapula sensor groups.
• Estimation accuracy was quantified using Normalized Root Mean Square Error (NRMSE) and Pearson correlation coefficient (ρ).
• The model incorporating sensors from all three groups (clavicle, shoulder, and scapula) demonstrated superior accuracy compared to other configurations.

Conclusions:

• The developed wearable sensor prototype shows promise for accurate scapular motion measurement.
• An optimized sensor arrangement, utilizing all three sensor groups, is essential for achieving high measurement accuracy.
• This technology has potential applications in sports science, rehabilitation, and ergonomic assessments.