Closing the Wearable Gap-Part V: Development of a Pressure-Sensitive Sock Utilizing Soft Sensors

Area of Science:

• Robotics
• Biomechanics
• Wearable Technology

Background:

• Accurate measurement of plantar pressure is crucial for understanding foot biomechanics and developing effective wearable health monitoring systems.
• Existing pressure measurement technologies can be limited by bulkiness, cost, or specific application constraints.

Purpose of the Study:

• To evaluate the efficacy of compressible soft robotic sensors (C-SRS) for inferring vertical and shear forces from plantar pressure measurements.
• To assess the feasibility of integrating C-SRS into a ground reaction pressure sock (GRPS) for wearable applications.

Main Methods:

• Thirteen volunteers performed dynamic movements (squats, weight shifts) while wearing C-SRS integrated into a sock.
• Pressure data from C-SRS were correlated with reference measurements from a BodiTrak Vector Plate and Kistler Force Plates.
• Sensor orientation (anterior-posterior and medial-lateral) effects were analyzed, and ARIMA modeling was used for data estimation.

Main Results:

• C-SRS demonstrated strong correlations with reference systems, with average Pearson correlation coefficients (R) exceeding 0.70 in 79% of comparisons to the BodiTrak system.
• Exceptional R-values (>0.90) were observed when comparing C-SRS to Kistler Force Plates during specific weight-shifting tasks.
• While both sensor orientations showed high R² values (0.952 A/P, 0.945 M/L), this indicated reduced effectiveness in inferring shear forces.

Conclusions:

• Compressible soft robotic sensors show significant potential for accurate plantar pressure measurement in wearable systems.
• The high correlation values support the feasibility of developing a ground reaction pressure sock (GRPS) using C-SRS for inferring normal pressures.
• Further research may be needed to optimize sensor design or algorithms for reliable shear force inference.