World-First Miniaturized Fiber-Optical Monitoring System Embedded In Composite Material

FP7 project SMARTFIBER paving the way toward smart composites

Nanoelectronics research center imec, Ghent University, and their 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. This achievement paves the way toward smart composites that enable continued and automatic monitoring of the structural health of the composite material in -for example- tidal blades, wind turbines, airplanes (fuselage, wings, …) or marine structures (masts, antennas, hulls of sail yachts, navy ships, 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 provided by Xenics. 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 FBGS international, it was casted in an epoxy shape specifically designed by Ghent University to minimize the impact on the composite material. Finally, 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 (AWG) acting as a spectrometer, forms the core of the sensor system and allows interrogating the Fiber Bragg Grating (FBG) sensors connected to it with high accuracy. The advantages of these FBG sensors compared to other strain monitoring techniques (e.g. electrical strain gauges) are their compactness, light weight, immunity to electromagnetic interferences (EMI), high resistance to corrosion, high temperature operation, and multiplexing capability. The FBG sensors, which exhibit a record small diameter and show unprecedented elongation at breakage, were specifically designed to minimally impact the strength of the composite material. Automatic techniques were developed to embed them in the composite. This, together with the use of silicon-based microfabrication processes on a well-established industrial infrastructure, will enable lowering the cost of embedded strain sensors substantially.

About imec
Imec performs world-leading research in nanoelectronics. Imec leverages its scientific knowledge with the innovative power of its global partnerships in ICT, healthcare and energy. Imec delivers industry-relevant technology solutions. In a unique high-tech environment, its international top talent is committed to providing the building blocks for a better life in a sustainable society. Imec is headquartered in Leuven, Belgium, and has offices in Belgium, the Netherlands, Taiwan, US, China, India and Japan. Its staff of over 2,080 people includes more than 670 industrial residents and guest researchers. In 2013, imec's revenue (P&L) totaled 332 million euro. For more information, visit www.imec.be.

About Xenics
Xenics is a pioneer of path-breaking infrared technology with a proven track record of more than ten years. Xenics designs and markets infrared imagers, cores and cameras of best-in-class image quality to support innovative R&D, industrial automation, machine vision, process control and high-end security applications. The company offers a complete portfolio of line-scan and 2-D area-scan products for the VisNIR, SWIR, MWIR and LWIR ranges. As a vertically integrated manufacturer with advanced production facilities and in-house know-how on detector, systems and software development, Xenics delivers state-of-the-art imaging solutions as well as specifically targeted and optimized custom designs. Due to its Western European location and a worldwide sales and service network, Xenics is able to support its customers with simplified export procedures.

About Fraunhofer IIS
Founded in 1985 the Fraunhofer Institute for Integrated Circuits IIS in Erlangen, today with more than 830 staff members, ranks first among the Fraunhofer Institutes concerning headcount and revenues. As the inventor of mp3 and co-inventor of the MPEG 4 AAC audio coding standard, Fraunhofer IIS has reached worldwide recognition.

It provides research services on contract basis and technology licensing. The research topics are: Audio and video source coding, multimedia realtime systems, digital radio broadcasting and digital cinema systems, integrated circuits and sensor systems, design automation, wireless, wired and optical networks, localization and navigation, imaging systems and nanofocus X-ray technology, highspeed cameras, medical sensor solutions and supply chain services. The budget of more than 102 million Euro is mainly financed by projects from industry, the service sector and public authorities. Less than 25 percent of the budget is subsidized by federal and state funds.

For more than 10 years wireless positioning, wireless communication and RFID have been core areas of expertise at Fraunhofer IIS. Our developments in these areas are the basis for numerous trends currently dominating the research landscape. Our highly qualified and experienced team of almost 40 scientists has convinced numerous small, medium and large scale businesses which now benefit from our knowledge and innovative power.

About FBGS
FBGS is a Belgium/Germany-based developer and manufacturer of high strength Fiber Bragg Gratings (FBG) using draw tower technology. These ‘Draw Tower Gratings’ - DTG - are commercialized by FBGS as an OEM component into the fiber optic sensing industry and are applied worldwide for both standard and tailored sensing applications in industries such as medical, oil&gas, composite, transport, process, civil & geo, telecom and R&D. For more information, visit www.fbgs.com.

About Optocap Ltd
Optocap Ltd provides contract packaging design and assembly services for a wide range of microelectronic and optoelectronic devices. Specifically with regards to photonic devices Optocap has extensive experience with packaging of transmitter, receiver and photonic integrated circuits devices.

Optocap’s assembly and packaging know-how enables customers to reduce costs, accelerate time to market and reduce risk in new developments.

Optocap’s assembly solutions span the full product life-cycle: from design through prototyping to volume manufacturing.

Optocap offers a range of assembly process and material knowledge including numerous optical coupling techniques, including fiber arrays and micro-optic alignment, optimized thermal management solutions and a variety of electrical interconnections including wire bonding for RF applications and flip chip.

About Airborne International
Airborne International provides advanced composite solutions for industrial market leaders in the Oil & Gas, Aerospace and Marine industries. As preferred supplier and OEM we design, develop, qualify and manufacture composite products for the most demanding applications.

Airborne’s expertise flourishes in high-demand territories, typically when metals prove to reach their limits in engineering possibilities as demands on product applications are steadily increasing. Airborne envisages the future of composites in design & build of ever larger series of products.

The role of Airborne Technology Centre (ATC) is to be at the forefront of new composite technologies to support this goal with an emphasis on industrialisation and manufacturing technology.

We focus on the technology development of:
• Thermoset manufacturing technology
• Thermoplastic manufacturing technology
• Manufacturing automation
• RTM

ATC is involved in a number of European and national projects, making us well embedded in the international research community on composites.

Airborne International headquarters is located in The Hague, The Netherlands, and has locations in Ijmuiden, The Netherlands and Girona, Spain. 

Find out more via the website www.airborne-international.com or contact Robbert Bakker, Managing Director ATC (r.bakker@airborne.nl).

About UGent
Ghent University was founded in 1817 and is one of the leading institutions of higher education and research in the Dutch speaking region of Western Europe today. Ghent University's eleven faculties are composed of more than 130 departments all together. These departments offer high-quality courses in every one of their scientific disciplines, each inspired by innovative research. Ghent University is an active partner in national and international educational, scientific and industrial cooperation.

The Mechanics of Materials and Structures (MMS) research group has a long-term track record in the study of the mechanics of composite materials and other non-homogeneous materials. The mechanical behavior of materials is studied under static and dynamic loading conditions, where dynamic loading ranges from (high) dynamic impact over vibrations till fatigue.
 Research is running on a variety of monitoring and non-destructive testing techniques such as optical fiber sensors, ultrasound, digital moiré techniques, digital image correlation.

The photonics research group of UGent (and associated with imec) is developing novel photonic integrated circuits, mostly using the silicon photonics platform. The focus is on the development of new devices and their application in telecom, optical interconnects and sensors.