Spatiotemporal mapping of plantar shear forces during human walking using a flexible thin-film sensor.

The integrated vertical and shear force components from the thin-film sensor showed good agreement with force plate reference data, confirming accuracy and reliability.

• Five healthy male adults participated in the walking experiments.
• Force outputs were sampled at 100 Hz.
• The force plate served as the reference standard for comparison.
• Both vertical (normal) and shear force components were validated against the force plate.

The thin-film sensor measured plantar normal and shear forces with a spatial resolution of 24×24 sensing points over a 312×312 mm area.

• The sensor covered a 312×312 mm measurement area.
• Sensing resolution was 24×24 points across that area.
• The sensor was described as a flexible thin-film design affixed to a force plate during experiments.
• Force outputs were sampled at 100 Hz.

Spatiotemporal shear maps revealed distinct phases of plantar shear loading direction and magnitude throughout the stance phase of walking.

• During early stance, posterior shear forces were observed beneath the heel.
• At mid-stance, a medial rotation of shear forces was detected.
• During push-off, anterior propulsion shear forces were observed beneath the forefoot.
• These findings characterize dynamic changes in both magnitude and direction of shear stress across the entire stance phase.

Plantar shear stress has been less investigated compared to plantar pressure due to measurement difficulties, motivating development of this sensing system.

• The paper notes that vertical and shear ground reaction forces play critical roles in gait mechanics and the development of foot pathologies.
• Measurement difficulties have historically limited investigation of plantar shear stress.
• The study aimed both to evaluate sensor accuracy and to characterize spatiotemporal features of plantar shear loading.
• Potential clinical applications cited include prevention of diabetic ulcers and hallux valgus.