This article describes a new technique to interrogate photonic biosensors for applications in the field of health. The first part presents a type of photonic biosensors: a planar, cyclic microresonator in polymer, shaped racetrack, coupled vertically to a straight waveguide used as input and output for the light. In order, to be adapted for biological applications, the sensor is inserted into an optofluidique cell and its surface is functionalized. The second part of the article describes the phase sensitive optical low coherence interferometer of LNE, proposed as a new interrogation technique of this type of biosensors. Originally developed to characterize, from a metrological point of view, fibre’s components used in the field of telecommunications, this Michelson interferometer with a broadband source has been adapted to such applications. Preliminary results in a biological domain highlight the relevance of this technique and of these microresonators for applications in the field of health.