Combined-blade open flow path device and joined body thereof

A combined-blade open flow path device which is a fluid flow path device where multiple flow paths are adjacent to each other, the combined-blade open flow path device comprising:

• a substrate configured to constitute a bottom portion of the flow paths;
• and
• a plurality of blades erected on a surface of the substrate, the plurality of blades being configured to constitute side walls of the flow paths,
• wherein:
• the blades are erected in a plurality of groups, each of the groups extending from an upstream side to a downstream side in a flow direction of a fluid with a space between each of the blades in the flow direction of the fluid in each of the groups for making conduction of the fluid between the adjacent flow paths possible,
• one end of one of the flow paths is configured to be in contact with the fluid and is configured to make a flow of the fluid possible,
• the blades include first blades and second blades,
• each of the first blades has a first length in the flow direction of the fluid,
• each of the second blades has a second length in the flow direction of the fluid,
• the second length is longer than the first length,
• the first blades are in an outermost portion of the flow paths,
• the second blades are in a central portion surrounded by the first blades.