Patent ID: 8166814

Claim:
A flow sensor for use with a fluid, the flow sensor comprising: a sensor chip; and a flow path forming member provided on the sensor chip and forming a flow path having a predetermined cross-sectional area for the fluid; wherein the sensor chip comprises: a substrate, the substrate comprising a concave part formed in an upper surface of the substrate; a flow rate detecting part formed on an electric insulating film coated so as to cover at least a part of the concave part; and a lead pattern extending from the flow rate detecting part to a point on an edge of the substrate; the flow path forming member comprises: a first flow path forming member having a plate shape and being provided with an inflow port and an outflow port, the first flow path forming member being transparent; a second flow path forming member having a plate shape and being provided with a through hole which forms the flow path; wherein the second flow path forming member is provided on the substrate, and the first flow path forming member is provided on the second flow path forming member; the through hole is configured so that ends of the through hole communicate with the inflow port and the outflow port; the first flow path forming member is joined with the second flow path forming member to form the flow path; the first flow path forming member further comprises a first notch provided on a side of the first flow path member and extending through a thickness of the first flow path member; the second flow path forming member further comprises a second notch provided on a side of the second flow path member and extending through a thickness of the second flow path member; the first notch and the second notch are configured so that the first notch and the second notch coincide with each other; and the first notch and the second notch are aligned with the point on the edge of the substrate to which the lead pattern is extended; the flow rate detecting part is arranged between the portions corresponding to the inflow port and the outflow port of the through hole.