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Mini fiber-optic monitor embedded in composite

02 Jul 2014

Researchers at Imec and Ghent University, Belgium, develop photonics strain-monitoring system for polymers and composite structures.

Nanoelectronics research center IMEC and Ghent University, both Belgium, and partners in the European FP7 project SMARTFIBER have demonstrated the world’s first miniaturized fiber-optical sensor system than can be fully embedded in a composite material. The developers say the achievement paves the way toward smarter composites that enable continued and automatic monitoring of the structural health of the composite material in – for example – tidal blades, wind turbines, airplane parts, or marine structures, such hulls of yachts and propellers.


The sensor system was assembled by Optocap on an electronic board designed by Xenics. The optical subsystem consists of a silicon photonics integrated circuit developed by imec and photodiodes and read-out ICs also provided by Xenics. German research center Fraunhofer IIS was responsible for the wireless interface. It provides power to the embedded system and at the same time reads out the acquired data at high speed.

After connecting the system to an optical fiber sensor chain manufactured by optical component company FBGS, it was cast inside an epoxy shape purpose-designed by Ghent University to minimize the sensor’s impact on the composite material. Together with the attached fiber sensor chain it was embedded in the blade of a tidal turbine by Airborne.

The silicon photonic integrated circuit, featuring an arrayed waveguide grating that acts as a spectrometer, forms the core of the sensor system. It can interrogate the connected Fiber Bragg Grating sensors. The benefits of these FBG sensors include: compactness, low weight, immunity to electromagnetic interference, high temperature operation and multiplexing capability.

The FBG sensors, which exhibit a “record” small diameter and show unprecedented elongation at breakage, are designed to minimally impact on the strength of the composite material. This, together with the use of silicon-based microfabrication processes on a well-established industrial infrastructure, can substantiallyreduce the cost of embedded strain sensors.

Following is a video showing the SmartFiber silicon photonics FBG interrogator:

EC gives IMEC ‘HR Excellence in Research’ award

Also, earlier this week, IMEC announced that it has been recognized by the European Commission, as it was given the Human Resources Excellence in Research award; recognition for IMEC’s human resource policy to “create the best possible employment and working conditions for researchers”.

The research organization commented that, during the past year, it has made an in-depth assessment of its HR strategy to develop a comprehensive plan to improve the quality of its "talent and career practices towards researchers". The European Commission congratulated the organisation for meeting all its award requirements.

IMEC’s action plan and the feedback from the EC can be found 

About the Author

Matthew Peach is a contributing editor to optics.org.

Iridian Spectral TechnologiesOptikos Corporation Hyperion OpticsUniverse Kogaku America Inc.Berkeley Nucleonics CorporationCHROMA TECHNOLOGY CORP.Alluxa
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