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32 st / February 2017 www.sea-technology.com ronment. Measurements based on the principle of fluorescence, the emission of light at a wave- length different than the excita- tion wavelength, are proven to be sensitive and specific. A number of commercially available in-situ fluorometers ex- ist, addressing parameters from bacterial components to chloro- phyll and from fluorescent dis- solved organic matter (FDOM) to polycyclic aromatic hydrocar- bons (PAHs). The bulk of these fluorometers are single channel in design, which means they in- corporate a single excitation and emission wavelength pair. Some devices come with a double- channel or triple-channel design, basically the integration of bun- dled single-channel designs in one housing. In the field of algae fluorescence, a few sensors are available that make use of multiple excitations for a single emission channel, thus addressing different pigments in the algae's photosyn- thetic apparatus, aiming to provide a more specific quan- tification of phytoplankton functional types. What these approaches have in common is their dedicated technical design toward individual target parameters. The TriOS MatrixFlu sensor is extending these capaci- ties through a new concept of matrix fluorescence inspired by the successful application of excitation-emission-matrix spectroscopy (EEM), a laboratory method to scan the full range of fluorescent signals of water samples with respect to dissolved components. The MatrixFlu is available in two versions. The ultraviolet (UV) version is targeting fluorescent dissolved organic matter and polycyclic aromatic hydro- carbons, therefore applying three dedicated UV excitation wavelengths, while the visible (VIS) version comes with a suite of violet, blue and yellow excitations and an additional near-infrared channel for the turbidity measurement. Both gies; sensors that are compact, autonomous, multifunctional integrated packages that could be deployed using free-floating devices or buoys, platforms or ships of opportunities includ- ing fishing vessels; data flow capabilities that include data acquisition, access and retrieval, storage, transmission, standard- ization and preprocessing, tak- ing advantage of the latest Web enablement; and sensors that are fully interoperable with ex- isting observing systems. These challenges are be- ing addressed by a group of "Oceans of Tomorrow" projects funded by the European Com- mission. At the system level, four projects are funded: COMMON SENSE (commonsenseproject.eu), NeXOS (nexosproject. eu), SCHeMA (www.schema-ocean.eu) and SenseOCEAN (www.senseocean.eu). These are developing a new genera- tion of sensors from acoustic to optical fluorometers to labs on a chip. The parameters observed range from temperature to ocean carbon to acoustics to heavy metal and plastics. The projects take the sensors/systems from design to in- tegration on a variety of platforms (including, for example, ships, autonomous vehicles and buoys) leading to field demonstrations in 2017. Working with small and medium- size enterprises, the objective is to have sensors that can be transitioned to production in the next two years. MatrixFlu: Innovative Optical Sensing It is instructive to look at one of the Oceans of Tomor- row sensors as an example of the progress in this new gen- eration. The MatrixFlu is a compact optical multifunctional sensor that was developed within the NeXOS project. Op- tical tools generally have high potential for cost-efficient sensing of biogeochemical parameters in the marine envi- Table 1: Range of parameters addressed by the 2013.2 Oceans of Tomorrow projects. Table 2: Exemplary wavelength matrix of a combined MatrixFlu-UV (violet area) and MatrixFlu-VIS (green area). Scat850 indicates the scaƩering signal at 850 nm. PAH = polycyclic aromaƟc hydrocarbon, PC = Phycocyanin, CHLa = Chlorophyll a and FDOM = fluorescent dissolved organic maƩer components.