, The seismic mass (4.2 mg) is suspended by waveguide bridges containing a BG @ 1.55 pm (L= 3 mm) -thus acting as strain guge-and is revealed by chemical anisotropic etching of the silicon wafer (fig. 10) Dynamic strain resolution is 6
, nuclear industry (containment barriers, steam pipes, storage sites), aeronautics (curing process monitoring, impact detection, health monitoring, shape control & vibration damping) and marine applications (lock gates Moreover, in a near future, other fields of application will be covered (high temperature measurements, extensometry, magnetometry, civil and nuclear robotics, medical sensors, chemical/biochemical sensing FBGs, mainly used as transducers in the sensors, are also increasingly integrated in instrumentation as in the demultiplexing unit itself (tracking FBGs, linear discriminator) Although the price of FBGs is continuously decreasing, the total cost of the system is still dominated by the cost of the acquisition unit so that the higher the number of transducers, the lower the cost per measurement point due to multiplexing capabilities. Letting alone special applications where BGs are surpassing transducers (e.g. measurement of temperature or strain in electromagnetic environment), FBGs are competitive only on large scale demonstrations. A key development is therefore the integration of the acquisition unit so as to decrease its cost and increase the market share. So, in Europe, the level of innovation is good and the first R&D demonstrators are leaving the laboratories to perform field trials in collaboration with industrial partners. Reliability of FBG transducers and systems is a great matter of concern as well and European collaborations act through COST Projects, Conclusion Bragg grating sensors are mainly used in Europe fix (( Structure monitoring >) applications. Most applications are civil engineering (mining, tunnels)). Current issue is the influence of BG manrd%mring process on high temperature erasure and mechanical reliability (static & dynamic fatigue stress
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