Electromechanical Impedance Sensing for Next-Generation Structural Health Monitoring Systems

Abstract

Structural Health Monitoring (SHM) is essential for ensuring the safety, serviceability, and longevity of civil infrastructure through continuous condition assessment. Among various SHM techniques, the Electromechanical Impedance (EMI) method using piezoelectric (PZT) transducers has gained considerable attention owing to its high sensitivity, simplicity, and capability for real-time local damage detection. This paper reviews the fundamental principles, sensing mechanisms, technical requirements, and practical applications of the EMI technique. The effects of key parameters, including PZT dimensions, excitation frequency, adhesive properties, sensing range, temperature variations, and damage assessment metrics, on monitoring performance are discussed. Applications of EMI-based SHM in concrete, steel, composite, bridge, pipeline, aerospace, and retrofitted structures are also reviewed. Recent developments in low-cost instrumentation, wireless sensing, energy harvesting, and dual-PZT configurations are examined, along with existing challenges and future research directions. The EMI technique offers significant potential for robust, cost-effective, and adaptable structural health monitoring and smart infrastructure management.