公开(公告)号：CA1314413C

公开(公告)日：1993-03-16

申请号：CA580021

申请日：1988-10-13

Applicant: ROSEMOUNT INC

Inventor： SITTLER FRED C ,  CRABTREE JAMES H

IPC: G01F1/68 ,  G01F1/684 ,  G01F1/692 ,  G01N27/18 ,  G01N30/02 ,  G01P5/12

Abstract: A thermal effect sensing device comprises a semiconductor substrate supporting an insulating layer which has a thin film of platinum deposited on it. Holes are etched through the semiconductor substrate and the insulating layer. The platinum film is shaped to provide a serpentine resistive element suspended over one of the holes . The serpentine element is suspended from the rim of the hole, but is otherwise unsupported. The resistive element has a low thermal mass and there is a low thermal resistance between the element and fluid in the sensor. The sensor senses thermal properties of the fluid in the sensor, such as mass flow or thermal conductivity. A second conductive film is insulatingly deposited on the first film to provide a resistive sensor electrically isolated from a resistive heating element .