Abstract: A system for analysis of a fluid, comprises a light source for radiating a beam of light an optical path for guiding at least part of the beam of light, a fluidic channel for guiding the fluid along the optical path, and a detector for detecting an optical characteristic of the light having propagated along the optical path. The optical path comprises a multimode interference structure, the multimode interference structure being arranged for providing a propagation of the beam of light in at least two propagation modes, the detector being positioned so as to receive light from each of the at least two propagation modes.

Abstract: A method for detecting an analyte in a fluid sample is disclosed. The method comprises: a) providing a measurement region and a reference region, the measurement region being provided with a receptor for binding the analyte; b) providing at least one light beam so as to travel along the measurement region and along the reference region; c) providing the fluid sample into at least the measurement region; d) detecting by means of a detector an optical pattern provided by the at least one light beam after having travelled along the measurement region and the reference region; and e) deriving a presence of the analyte in the fluid sample from the detected optical pattern, wherein prior to c) a blocking fluid is provided along the measurement region and along the reference region.