Fabrication of monolithically integrated flow sensor on tube

A monolithic-type flow sensor was developed to simplify the packaging process for microelectro mechanical system (MEMS) fluidic devices. In our design, a heater element for sensing flows as part of a thermal flow sensor was formed on the outside surface of a thin film in a tube, enabling us to connect electrical wiring from it to the outside of the tube directly. The monolithic-type flow sensor was produced by applying photolithography on a cylinder surface and transferring a cylindrical parylene film structure to the outside of the skeleton tube by using an adhesive heat-shrinkable tube. The relationship between the input power of the sensor and the flow rate obeyed King's equation under the flow conditions for 0–2000 sccm. The response time of 116 ms, which is comparable to that of commercially available mass flow controllers, was obtained.