Preliminary development and validation of a textile-based pressure-sensing system for lower-limb prosthetic sockets

The socket is an essential component of prostheses and critical to the mobility, quality of life, and independence of individuals with lower-limb loss. A poor-fitting socket can lead to residual limb health issues, gait abnormalities, and prosthesis abandonment. To mitigate these risks, prosthetists routinely evaluate socket fit, but current assessments rely largely on subjective measures, which may not consistently ensure optimal outcomes. The use of pressure sensors at the limb-socket interface could enhance these evaluations, yet challenges with practicality and wearability have limited their clinical adoption. To address these gaps, we developed and evaluated a prosthetic sock with integrated textile-based pressure-sensing cells.

Individual cells were first loaded to evaluate sensitivity, repeatability, and drift. Then, a surrogate residual limb was fabricated from silicone and 3D-printed components to assess performance at the limb-socket interface. The sensitivity test demonstrated the ability to detect load changes equivalent to 5% of the maximum load throughout the full range, while the repeatability evaluation resulted in an intraclass correlation coefficient of 0.998 (0.996-1.000) and a percentage coefficient of variation (CV) below 2%. The average drift over 10 min was 3.03 ± 0.44%. When loading the residual limb in the neutral standing position, three out of four sock cells tested at the limb-socket interface showed percentage CVs below 10%. Finally, all cells tested detected changes in socket pressure distribution under simulated gait events when applying a load of 600 N.

These results were similar to commonly used off-the-shelf pressure sensors, and the sock performance is, therefore, promising. However, further development is required, including form factor improvements, implementation of shear-sensing capabilities, calibration, and validation with prosthesis users.