A device for analyzing a liquid sample, comprising: a first plate, a second plate, and spacers (41,42,43), wherein: i. the plates (10,20) are movable relative to each other into different configurations; ii. one or both plates (10,20) are flexible; iii. the first plate has, on its inner surface, a first and a second sample contact areas at different locations, and the first plate has a first and second thickness at the first and second sample contact areas, respectively, wherein the sample contact areas are for contacting a sample suspected of containing a target analyte, and wherein the first thickness is different from the second thickness; iv. the spacers (41,42,43) are fixed to the first plate inner surface, and have a predetermined substantially uniform height (L1, L2, L3) in each sample contact area, wherein the heights of spacers in different sample areas differ from one another; and v. each of the spacers (41,42,43) has a top end (411,421,431), and the top ends of the spacers (411,421,431) are substantially aligned in one surface; wherein one of the configurations is an open configuration, in which: the two plates (10,20) are partially or entirely separated apart, the spacing between the plates (10,20) is not regulated by the spacers (41,42,43), and the sample is deposited on one or both of the plates (10,20); and wherein another of the configurations is a closed configuration, which is configured after the sample deposition in the open configuration, and in the closed configuration: at least part of the deposited sample is compressed by the two plates (10,20) into a layer that is confined by the two plates (10,20) and has a respective substantially uniform thickness over each of the sample contact areas, wherein the uniform thickness of the layer is confined by the respective sample contact area and is regulated by the plates (10,20) and the spacers (41,42,43) in the respective sample contact area. i. the plates (10,20) are movable relative to each other into different configurations; ii. one or both plates (10,20) are flexible; iii. the first plate has, on its inner surface, a first and a second sample contact areas at different locations, and the first plate has a first and second thickness at the first and second sample contact areas, respectively, wherein the sample contact areas are for contacting a sample suspected of containing a target analyte, and wherein the first thickness is different from the second thickness; iv. the spacers (41,42,43) are fixed to the first plate inner surface, and have a predetermined substantially uniform height (L1, L2, L3) in each sample contact area, wherein the heights of spacers in different sample areas differ from one another; and v. each of the spacers (41,42,43) has a top end (411,421,431), and the top ends of the spacers (411,421,431) are substantially aligned in one surface; wherein one of the configurations is an open configuration, in which: the two plates (10,20) are partially or entirely separated apart, the spacing between the plates (10,20) is not regulated by the spacers (41,42,43), and the sample is deposited on one or both of the plates (10,20); and wherein another of the configurations is a closed configuration, which is configured after the sample deposition in the open configuration, and in the closed configuration: at least part of the deposited sample is compressed by the two plates (10,20) into a layer that is confined by the two plates (10,20) and has a respective substantially uniform thickness over each of the sample contact areas, wherein the uniform thickness of the layer is confined by the respective sample contact area and is regulated by the plates (10,20) and the spacers (41,42,43) in the respective sample contact area.