Abstract: A monitoring device of biological cells including: a fluidic channel in which a fluid including biological cells is made to flow, including a first and second glass walls placed in parallel and a reflective surface adjoined to the second wall; and a piezoelectric transducer, the piezoelectric transducer emitting acoustic waves creating a force acting on the biological cells, making them flow substantially along a single motion plane. The external interface between the first wall and the exterior of the fluidic channel and the reflective surface are configured to function as a Fabry-Perot interferometer, such that the motion planes sensibly perpendicular to the optical axis of the Fabry-Perot interferometer. The finesse of the interferometer is lower than 10.