Combined compression-tension strain sensor over 1  µε-20  mε by using non-uniform multiple-core-offset fiber

Area of Science:

• Materials Science
• Optical Engineering
• Structural Engineering

Background:

• Structural health monitoring requires precise measurement of both compressive and tensile strains.
• Existing strain sensors often struggle to provide high resolution across a wide dynamic range, especially in combined compression-tension scenarios.

Purpose of the Study:

• To develop and demonstrate a novel fiber optic strain sensor capable of measuring combined compression and tension with a large strain range and high resolution.
• To enable accurate deformation monitoring in steel structures experiencing co-existing compressive and tensile strains.

Main Methods:

• Fabrication of strain sensors using non-uniform multiple-core-offset fibers.
• Utilizing core-offset splicing of non-uniform fiber segments to create asymmetric waveguides.
• Leveraging enhanced multi-mode interference induced by high-order modes in silica cladding and air.

Main Results:

• Realization of combined compression-tension strain sensors with a range from 1 micro-strain to 20 milli-strain.
• Achieved sensitivity of 7.93 pm/µε for micro-strain measurement with a 1.7 µε step.
• Demonstrated a tensile strain coefficient of 1.298 nm/mε for 13.2 mε and a compressive strain coefficient of -1.251 nm/mε for 20.1 mε.

Conclusions:

• The developed non-uniform multiple-core-offset fiber sensors effectively address the need for large-range, high-resolution strain measurement in structural monitoring.
• The unique sensor design enables simultaneous measurement of both compressive and tensile strains, crucial for assessing the integrity of steel structures.
• This technology offers a promising solution for advanced structural health monitoring, enhancing safety and maintenance protocols.