Homogeneous assay

A device for a homogeneous assay, comprising:

• a first plate, a second plate, spacers, a plurality of particles, and a capture agent, wherein:
• (i) the first and second plates are movable relative to each other into different configurations, including an open configuration and a closed configuration;
• (ii) each of the plates has, on its respective inner surface, a sample contact area for contacting a sample suspected of containing an analyte;
• (iii) the spacers are fixed on the inner surface of the first plate, at least one of the spacers is inside the sample contact area of the first plate, the spacers have a predetermined uniform height that is equal to 100 μm or less;
• (iv) the capture agent is immobilized on a surface of the plurality of particles, wherein the capture agent is capable of specifically binding and immobilizing the analyte;
• and
• (v) the plurality of particles are (a) distributed on the sample contact area of the first plate, except the areas occupied by the spacers, and (b) are temporarily or permanently fixed on the first plate;
• wherein in the open configuration, the two plates are partially or entirely separated apart, the spacing between the plates is not regulated by the spacers, and the sample is deposited on one or both of the plates;
• and
• wherein in the closed configuration, which is configured after deposition of the sample in the open configuration:
• at least part of the sample is compressed by the two plates into a layer of uniform thickness, the uniform thickness of the layer is confined by the inner surfaces of the plates and is regulated by the plates and the spacers.