Method of collecting target cells

A method of collecting target cells, the method comprising:

• providing a cell collection device comprising a conduit defining a fluid channel, a first screen defining pores and a second screen defining second pores, the pores of the first screen comprising a first pore, the pores of the second screen comprising a second pore, the first and second screens being arranged in the fluid channel such that liquid flowing through the fluid channel in a flow direction passes the first screen first and the second screen second,
• wherein the first and second screens are movable relative to each other along the flow direction between a first configuration and a second configuration of the cell collection device, wherein in the first configuration, the first and second screens are at a first distance therebetween in the flow direction whereas in the second configuration, the first and second screens are at a second distance therebetween in the flow direction that is larger than the first distance,
• wherein in the first configuration, the first and second screens in combination form a combined filter, in which the first pore of the first screen and the second pore of the second screen are partially overlapping when viewed in the flow direction such that the combined filter is configured to screen target cells that would pass the first screen and the second screen individually, whereas in the second configuration, each of the first and second screens is to act independently;
• flowing a fluid composition comprising the target cells from a first end of the fluid channel toward a second end of the fluid channel in the flow direction while the cell collection device is in the first configuration, and screening at least part of the target cells by the combined filter and allowing at least part of the rest of the fluid composition to pass through the combined filter toward the second end of the fluid channel;
• subsequently, moving the first screen relative to the second screen along the flow direction from the first configuration to form the second configuration, to permit at least part of the target cells screened by the combined filter in the first configuration to pass the first screen first and then the second screen in the flow direction;
• and
• collecting at least part of the target cells at the second end of the fluid channel,
• wherein the conduit comprises a first tube and a second tube that are arranged along the flow direction, wherein the first screen is attached to the first tube, and the second screen is attached to the second tube.