An Embeddable Strain Sensor with 30 Nano-Strain Resolution Based on Optical Interferometry

Abstract

Abstract:A cost-effective, robust and embeddable optical interferometric strain sensor with nanoscale strain resolution is presented in this paper. The sensor consists of an optical fiber, a quartz rod with one end coated with a thin gold layer, and two metal shells employed to transfer the strain and orient and protect the optical fiber and the quartz rod. The optical fiber endface, combining with the gold-coated surface, forms an extrinsic Fabry-Perot interferometer. The sensor was firstly calibrated, and the result showed that our prototype sensor could provide a measurement resolution of 30 nano-strain (nε) and a sensitivity of 10.01 µε/µm over a range of 1000 µε. After calibration of the sensor, the shrinkage strain of a cubic brick of mortar in real time during the drying process was monitored. The strain sensor was compared with a commercial linear variable displacement transducer, and the comparison results in four weeks demonstrated that our sensor had much higher measurement resolution and gained more detailed and useful information. Due to the advantages of the extremely simple, robust and cost-effective configuration, it is believed that the sensor is significantly beneficial to practical applications, especially for structural health monitoring.

NSHT: New Smart Hybrid Transducer for Structural and Geotechnical Applications

“…NSHT can be assembled in implants and safely transported thanks to its design features that also can avoid breaking during transportation and installation, overcoming the drawbacks of existing solutions based on distributed sensors. [58][59][60][61][62][63] In this paper, we propose two examples of the application of NSHT: the first as a smart inclinometer and the second as a Structural Health Monitoring and Reinforcement device (SHMR). In these two applications, we analyze the accuracy and the reliability of the NSHT transducer using a conventional optical acquisition system.…”