Method for detecting organisms in a diluted sample

A method for detecting organisms in a liquid sample, the method comprising the steps:

• (a) providing particles in a liquid medium and subjecting said particles to a hydrodynamic flow, in a capture area, wherein the organisms to be detected are capable of binding to these particles;
• (b) circulating the sample through the capture area;
• (c) measuring a physical property of the capture area, during and/or after circulating the sample, so as to deduce therefrom the presence or the concentration or the nature of the organisms in the sample;
• and
• (d) retaining the particles in the capture area between the inlet and the outlet of the hydrodynamic flow in the form of a fluidized bed when the capture area is subject to a hydrodynamic flow, in which the particles suspended in the flowing liquid medium behave like a fluid, are in motion relative to each another, and may adapt their mutual configuration to the shape of a chamber in which they are contained, but are not globally driven by said liquid medium, during at least part of the steps of circulating the sample and/or measuring a physical property.