Abstract
Developing technologies capable of constantly assessing and optimizing day-to-day activities has been a research priority for several years. A key factor in such technologies is the use of highly sensitive sensors to monitor in real-time numerous parameters, such as temperature and load. Due to their unique features, optical fiber sensors became one of the most interesting and viable solutions for applications dependent on those parameters. In this work, we present an optical fiber load sensor, called load cell, based on Fabry–Pérot hollow cavities embedded in a polymeric material. By using the load cells in a parallel configuration with a non-embedded hollow cavity, the optical Vernier effect was generated, allowing maximum sensitivity values of 0.433 nm N−1 and 0.66 nm °C−1 to be attained for vertical load and temperature, respectively. The proposed sensor’s performance, allied with the proposed configuration, makes it a viable and suitable device for a wide range of applications, namely those requiring high thermal and load sensitivities.
Highlights
Sensitivity by Optical Vernier Effect.Optical fiber sensors (OFSs) have been used extensively in recent years in several fields, mainly due to their intrinsic advantages, such as their light weight, immunity to electromagnetic fields, multiplexing capabilities, electrical passiveness at the point-of-care, and multiparameter sensing [1,2]
One of the most attractive and commonly used techniques to increase the sensitivity of optical fiber sensors is the optical Vernier effect (OVE)
A novel optical fiber sensor architecture for vertical load sensing was developed based on hollow Fabry–Pérot interferometer (FPI) cavities embedded in epoxy resin (LiquidLens Advanced)
Summary
Despite being solely used within interferometry-based OFSs, the inherent advantages of this effect, such as the possibility to tune OFSs’ sensitivities and develop highly compact devices, have allowed researchers to reach unprecedented sensitivity values, mainly in applications for temperature [3,4], strain [5,6], magnetic fields [6,7] and refractive index monitoring [8,9]. The sensors’ sensitivity was magnified using the optical Vernier effect, resulting from coupling, in a parallel configuration, the embedded sensor with an additional FPI cavity insensitive to temperature variations, eliminating the need to adopt complex isolation schemes or mathematical compensation methods. The attained results, allied with the low-cost fabrication methods and devices’ compactness, unveil the enormous potential of this sensor’s configuration to be used in a wide range of different applications, acting either as a load cell or temperature sensor. Sensors 2021, 21, 7737 sensor’s configuration to be used in a wide range of different applications, acting either a a load cell or temperature sensor
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