Abstract: A sample analysis device (9) comprises a sample receiving well (7) configured to receive a liquid sample (4) comprising rolling circle amplification products (RCPs) (5). The device (9) also comprises a filter membrane (1) permeable for liquid of the liquid sample (4) but substantially impermeable for RCPs (5) in the liquid sample (4). The sample receiving well (7) is defined in the filter membrane (1) or is in connection with the filter membrane (1). An absorption layer (3) is in liquid connection with the filter membrane (1) and is configured to suck liquid from the liquid sample (4) received in the sample receiving well (7) through the filter membrane (1) by capillary force. The dimensions of the sample receiving well (7) are restricted to a field of view of an optical sensing device (10).