Research on Innovative Structural Design and Pressure Response Analysis of Flexible Piezoresistive Smart Insoles

Abstract

Footwear sensors, as an important platform for acquiring human motion information, hold broad application prospects. This paper systematically reviews the research progress and challenges of smart insoles in terms of sensing principles, system integration, and structural design. To address the common oversight in existing studies regarding the influence of structural features on sensing performance, a multi-point pressure - detection insole system based on the flexible piezoresistive material Velostat was designed and fabricated. The system employs an ESP32 - S3 and an ADS1115 for signal acquisition, while real - time visualization of plantar pressure and the center of pressure (COP) is achieved using Processing and Python. Experimental results show that the system can reliably distinguish different postures: total plantar pressure increases by approximately 35 - 50% during squatting compared to standing, and the COP shifts forward by an average of 20 - 35% in the anterior – posterior direction. All three subjects exhibited consistent trends, verifying the system’s sensitivity and stability in posture recognition. Building on this, five structural models with different geometric configurations were fabricated using 3D printing. Results indicate that all structures exhibit a resistance decrease of more than 85% under loading, while the s5 structure shows the smallest fluctuation during repeated loading—only 2 - 3 Ω—demonstrating that geometry has a substantial impact on sensitivity, drift, and repeatability. This study provides a foundation for future structural customization and performance optimization for various application scenarios, such as fall monitoring for older adults, rehabilitation training assessment, and motor performance analysis, thereby enhancing the practical applicability and scalability of smart insole systems.