spectroscopy the device includes a waveguide a source of electromagnetic radiation coupled to the waveguide on the entry side and a detector coupled to the waveguide on the exit side for detecting electromagnetic radiation wherein the waveguide is arranged in contact with the fluid in at least certain sections between its entry side and its exit side an electrode arrangement is also provided which is designed to generate an inhomogeneous electric field in the direct environment of the waveguide said field exerting a dielectrophoretic force on polarisable particles in the fluid which moves these particles towards or away from the waveguide a corresponding method is presented application_number US 201214353527 A description a sample embodiment of the device of the invention is shown in fig1 the device has a waveguide in the form of an optical fiber 10 which is arranged concentrically in a tube 12 of a flow cell 14 the flow cell 14 moreover comprises an inlet 16 and an outlet 18 for the fluid being analyzed the tube 12 of the flow cell 14 is sealed at both ends and has there a plug connection 20 for contacting an electrode arrangement 36 said electrode arrangement 36 is shown in detail in fig2 it comprises a wirelike first electrode 38 which is wound in spiral or helical manner about the optical fiber 10 the first electrode 38 while continuous nevertheless sections of the first electrode alternately follow uncovered sections of the waveguide surface looking in the.