Wireless and passive surface acoustic wave sensors for engineering applications: a review

Purpose With wireless and passive operation as its core technical advantage, this paper aims to systematically review the working principles, technical characteristics and progress in the engineering applications of surface acoustic wave (SAW) sensors, thereby providing a comprehensive reference for further research and the industrialization of wireless passive SAW sensor technology. Design/methodology/approach This work provides a systematic overview of SAW sensing technology for engineering applications, covering practical progress in aerospace engineering, industrial manufacturing, environmental monitoring, transportation engineering and nuclear energy. The discussion considers both the sensing target and its engineering maturity, highlighting temperature, strain, pressure and torque sensing as relatively mature wireless passive directions, while treating gas and humidity sensing as emerging film-functionalized technologies that continue to face challenges in wireless validation, long-term reliability and practical deployment. The review also analyzes how advanced materials, structural optimization and wireless passive technologies improve sensor performance and environmental adaptability, and it identifies the principal technical bottlenecks and prospective development directions. Findings The review clarifies the technical boundaries of wireless passive SAW sensing. Physical sensing targets, including temperature, strain, pressure and torque have reached a relatively mature stage of wireless passive engineering deployment, whereas chemical sensing directions, such as gas and humidity sensing, still face key bottlenecks related to sensitive-film stability, temperature-humidity compensation and acoustic attenuation. Fully passive engineering applications of these chemical sensors therefore remain limited. Other technical constraints include material limitations, packaging challenges and signal interference, while the field is progressing toward greater integration, multiparameter sensing and system-level synergy. Research limitations/implications The review clarifies the technical boundaries of wireless passive SAW sensing. Physical sensing targets, including temperature, strain, pressure, and torque have reached a relatively mature stage of wireless passive engineering deployment, whereas chemical sensing directions, such as gas and humidity sensing, still face key bottlenecks related to sensitive-film stability, temperature-humidity compensation and acoustic attenuation. Fully passive engineering applications of these chemical sensors therefore remain limited. Other technical constraints include material limitations, packaging challenges and signal interference, while the field is progressing toward greater integration, multiparameter sensing and system-level synergy. Originality/value This review systematically examines the development of wireless passive SAW sensors, from their operating principles and multiscenario applications to their technical bottlenecks. It explicitly distinguishes the differences in engineering maturity between physical and chemical sensing and proposes a clear roadmap for future technical research and industrial deployment.