Magnitude and Timing of Smart Sensor Loads During Walking​

• Kaeden Monroe, Mechanical Engineering, University of Delaware

• Jill Higginson, Mechanical Engineering, University of Delaware

Vertical ground reaction forces (vGRFs) provide critical insight into gait dynamics, with loading patterns across heel strike, midstance, and toe-off commonly visualized as an “M-shaped” curve. However, vGRF measurement remains largely confined to laboratory settings due to the cost and immobility of force platforms. There is increasing clinical demand for accessible, field-deployable alternatives in applications ranging from prosthetic tuning and post-surgical rehab to athletic performance monitoring. We developed and evaluated a low-cost, wearable insole system equipped with two piezoresistive sensors—positioned under the forefoot and hindfoot—as a proof-of-concept for mobile gait analysis. Ten healthy participants performed level walking, stair ascent, and descent at self-selected speeds. Sensor outputs were analyzed using peak detection and thresholding methods, and results were compared to established vGRF patterns from existing literature. The system consistently detected stance phases and transition events, with sensor patterns closely aligning with expected loading distributions. While midstance phases were more challenging to isolate—particularly during stair descent—intra-subject variability remained low, indicating robust signal reliability across users. This study demonstrates the feasibility of using a simple two-sensor insole system to detect relative vGRF changes across dynamic activities. Future work will explore model-based calibration to absolute force values, exploring the integration of inertial measurement units (IMUs), and wireless feedback delivery via mobile applications. These developments aim to extend gait monitoring and rehabilitation support beyond clinical environments.