Sorting and sensing of dielectric microparticles by a multiphysics approach: integrated electro-opto-fluidic function for environmental application
Résumé
Integrated photonics on glass offers advantages for sensing applications because of its relative low cost and its detection sensitivity. In this paper we discuss the design, fabrication and characterization of a micro device for sorting and sensing dielectric microparticles. The target application is the analysis of bacteria used as sentinel for water pollution. The sorting function, that does not include any functionalization layer, is done by means of dielectrophoretic forces. They are induced by castellated electrodes fed by a low frequency electric signal. The sensing function is obtained by a surface waveguide that is perturbed by the particles collected on top of it by dielectrophoresis. We first discuss the co-integration of the castellated electrodes with an optical waveguide. An efficient interaction of polystyrene beads with the guided light (up to 50% of intensity modulation) is then simulated and observed experimentally. We also showed that this multiphysics device can be used as a sensor, presenting curves of the intensity modulation depending on the concentration of beads. The attenuation in the optical signal varies between 2 and 5 dB with particle concentrations ranging from 136 to 455 beads per µL in the analyte.
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