Flow cell unit

A flow cell unit, comprising:

• a flow cell which is made of a light transmissive material and includes a space in which liquid flows therein, the flow cell comprising a connecting surface provided with an inlet hole and an outlet hole, the inlet hole communicates with one end side of the space to cause the liquid to flow into the space, and the outlet hole communicates with the other end side of the space to cause the liquid to flow out from the space;
• a joint member which includes a flow cell opposing surface opposed to the connecting surface of the flow cell, an inlet pipe connection port to which an inlet pipe for supplying the liquid to the space in the flow cell is connected, and an outlet pipe connection port to which an outlet pipe for causing the liquid flowing out from the space to flow therethrough is connected, the joint member comprises an inlet flow path for communicating between the inlet hole of the flow cell and the inlet pipe connection port and an outlet flow path for communicating between the outlet hole of the flow cell and the outlet pipe connection port therein, an end of the inlet flow path and an end of the outlet flow path are provided at positions opposed to the inlet hole and the outlet hole in the flow cell opposing surface, respectively;
• and
• a gasket which has a flat shape, includes a main flat surface, and is sandwiched between the connecting surface of the flow cell and the flow cell opposing surface of the joint member, an inlet communication hole for communicating between the inlet hole and the inlet flow path and an outlet communication hole for communicating between the outlet hole and the outlet flow path are provided in the main flat surface, and a deformation absorbing structure for absorbing deformation of the gasket is provided between the inlet communication hole and the outlet communication hole in the main flat surface.