A pressure and shear sensor system for stress measurement at lower limb residuum/socket interface

Area of Science:

• Biomedical Engineering
• Prosthetics and Orthotics
• Biomechanics

Background:

• The interface between a lower limb prosthesis socket and the residual limb is critical for comfort and function.
• Accurate measurement of pressure and shear forces at this interface is challenging but essential for optimizing prosthetic fit and preventing skin issues.

Purpose of the Study:

• To develop and characterize a novel sensor system for measuring pressure and shear at the lower limb residuum/socket interface.
• To evaluate the system's performance in laboratory settings and during an amputee walking test.

Main Methods:

• A flexible sensor unit and a wireless data acquisition unit were developed.
• Static and dynamic performance were characterized using a mechanical test machine.
• A pilot study involved placing sensors on a knee disarticulation amputee during walking.

Main Results:

• The sensor system demonstrated high linearity (≤3.8% error) and resolution (0.9 kPa pressure, 0.2 kPa shear).
• Dynamic characterization showed hysteresis errors of ~15% for pressure and ~8% for shear.
• Peak pressure and shear recorded during amputee walking were approximately 58 kPa and 27 kPa, respectively.

Conclusions:

• The developed sensor system shows high accuracy and potential for clinical application.
• It can provide valuable dynamic coupling information at the residuum/socket interface.
• This technology can serve as an assistive tool for prosthetic socket design, fit, and residual limb health monitoring.