An apparatus (100, 400, 1000) for conducting assays on samples and/or processing of samples, said apparatus comprising: a cylindrical sample holder (111, 411, 1011) for holding a sample at a lateral surface of the cylindrical sample holder, wherein said cylindrical sample holder is rotatably arranged; wherein said cylindrical sample holder is configured to be at least partly covered by a liquid layer (107, 407, 1007); a liquid dispensing means (400a-f) configured to add liquid to the liquid layer, wherein the liquid dispensing means is connected to a first container (428a-f) for holding the liquid; a reagent dispensing means (400a-f) configured to add a reagent to the liquid layer, wherein the reagent dispensing means is connected to a second container (428a-f) for holding the reagent; a liquid contacting means (105, 1005) configured to distribute liquid within said liquid layer, wherein said liquid contacting means comprises a plate-like element (105, 1005) having a substantially flat surface adapted to contact the liquid layer, the plate like element being flexibly assembled in relation to the cylindrical sample holder, such that the plate-like element can be arranged at a first predetermined distance from the cylindrical sample holder when no external forces are acting on the plate-like element, and at a second, larger distance from the cylindrical sample holder when the liquid layer is exerting a force on the plate-like element upon rotation of the cylindrical sample holder, wherein the plate-like element is attached to a force controlling element configured to control the amount of force that the plate-like element exerts on the liquid layer, wherein the force controlling element comprises a flexible portion configured to be contracted upon application of a force from the liquid layer upon rotation of the cylindrical sample holder, thereby increasing the distance between the plate-like element and the sample holder as long as the force is applied. a cylindrical sample holder (111, 411, 1011) for holding a sample at a lateral surface of the cylindrical sample holder, wherein said cylindrical sample holder is rotatably arranged; wherein said cylindrical sample holder is configured to be at least partly covered by a liquid layer (107, 407, 1007); a liquid dispensing means (400a-f) configured to add liquid to the liquid layer, wherein the liquid dispensing means is connected to a first container (428a-f) for holding the liquid; a reagent dispensing means (400a-f) configured to add a reagent to the liquid layer, wherein the reagent dispensing means is connected to a second container (428a-f) for holding the reagent; a liquid contacting means (105, 1005) configured to distribute liquid within said liquid layer, wherein said liquid contacting means comprises a plate-like element (105, 1005) having a substantially flat surface adapted to contact the liquid layer, the plate like element being flexibly assembled in relation to the cylindrical sample holder, such that the plate-like element can be arranged at a first predetermined distance from the cylindrical sample holder when no external forces are acting on the plate-like element, and at a second, larger distance from the cylindrical sample holder when the liquid layer is exerting a force on the plate-like element upon rotation of the cylindrical sample holder, wherein the plate-like element is attached to a force controlling element configured to control the amount of force that the plate-like element exerts on the liquid layer, wherein the force controlling element comprises a flexible portion configured to be contracted upon application of a force from the liquid layer upon rotation of the cylindrical sample holder, thereby increasing the distance between the plate-like element and the sample holder as long as the force is applied. a plate-like element (105, 1005) having a substantially flat surface adapted to contact the liquid layer, the plate like element being flexibly assembled in relation to the cylindrical sample holder, such that the plate-like element can be arranged at a first predetermined distance from the cylindrical sample holder when no external forces are acting on the plate-like element, and at a second, larger distance from the cylindrical sample holder when the liquid layer is exerting a force on the plate-like element upon rotation of the cylindrical sample holder, wherein the plate-like element is attached to a force controlling element configured to control the amount of force that the plate-like element exerts on the liquid layer, wherein the force controlling element comprises a flexible portion configured to be contracted upon application of a force from the liquid layer upon rotation of the cylindrical sample holder, thereby increasing the distance between the plate-like element and the sample holder as long as the force is applied.