Coaxial Cable Sensing: Review and Perspective

The development of sensors has been a hot research topic in both scientific and industrial communities over the past decades. In recent years, a new sensing technology based on coaxial cables has emerged. Inspired by the fiber Bragg grating and motivated by the demand for structural health monitoring, coaxial cable Bragg gratings were first proposed and demonstrated with superior large strain capability ( $>$ 5%). Mimicking the mature sensing modalities in fiber-optic sensors, coaxial cable sensors are developed to be promising alternatives for fiber-optic sensors in harsh-environment applications involving heavy duty, large strains, high pressures, and high temperatures. Over the past decade, with plenty of efforts being poured into this research direction, a family of coaxial cable sensors with high mechanical robustness, ease of fabrication, high-temperature tolerance, and low system cost have been developed, which has also found wide applications in a diverse array of scenarios, from civil and geological to biochemical engineering. In this article, we provide an overview of reported coaxial cable sensors in the past ten years. Challenges of existing coaxial cable sensing technologies and perspectives on the development of a new generation of ultrasensitive coaxial cable sensors operating at subgigahertz are discussed.