The present invention relates to an apparatus for conducting assays on samples and/or processing of samples. The apparatus comprises a rotatably arranged cylindrical sample holder for holding a sample at a lateral surface of the cylindrical sample holder. The cylindrical sample holder is configured to be at least partly covered by a liquid layer. The apparatus further comprises a liquid dispensing means configured to add liquid to the liquid layer, a reagent dispensing means configured to add a reagent to the liquid layer and a liquid contacting means configured to distribute liquid within said liquid layer. The liquid contacting means comprises a plate-like element flexibly assembled in relation to the cylindrical sample holder. The present invention also relates to a method for conducting assays on samples and/or processing of samples.