Temperature insensitive optical fiber sensor for pressure, 3D mechanical strain and vibration monitoring

Many industrial processes require continuous monitoring of pressure, whilst measuring mechanical strain is crucial to assess the integrity of many civil engineering structures. Most commercially available pressure sensors are cross-sensitive to temperature transients, leading to erroneous pressure measurements. This requires implementing correction mechanisms to eliminate the effect of temperature changes, which increases the system cost and complexity. In addition, most strain sensors are sensitive to strain along one axis only. This means that multi-axial strain can only be measured by installing multiple sensors on dedicated and bulky mounts that need to be attached to the structure under test.

Solution

The Brussels Photonics Team B-PHOT of the VUB has developed a unique sensor based on optical fiber technology. The sensor size is a few mm long and has an outer diameter of 125 µm. It allows measuring pressure in a range of up to 1000 bar without being cross-sensitive to temperature changes. Whilst this sensor can be used independently in a packaged form, its small size allows embedding the device within materials to serve as an internal transverse and shear strain sensor. This allows monitoring internal residual strain in materials as well as carrying out static and dynamic load monitoring inside these materials, and even detecting the presence and growth of disbonds in glued joints, all of this to support structural health monitoring applications.

The sensor has already been licensed to FBGS International (www.fbgs.com) for applications in oil and gas industry.

Competitive advantages

  • No cross-sensitivity to temperature fluctuations and immune to electromagnetic interference
  • Ultra-small and minimally intrusive, embeddable within materials
  • Fast response with measurement frequencies at kHz level, strain measurement resolution down to 1 µstrain, pressure measurement resolution down to 20 kPa
  • Up to 40 sensors on a single wire/channel

Interested parties can contact

VUB TechTransfer
Hugo Loosvelt
[T]: +32 (0)2 629 38 65 or 22 07
[E]: hugo.loosvelt@vub.ac.be

Brussels Photonics Team – B-PHOT
Francis Berghmans
[E]: fberghma@vub.ac.be
Thomas Geernaert
[E]: tgeernae@vub.ac.be

Patent details

EP2502102, CA2781555, and US8958676 Birefringent micro-structured optical fiber for sensor application
PCT/EP2015/050750 Microstructural optical fibre, composite structure, method and use for measuring shear load in a composite structure

Download a printable pdf here.