In-Tube-Center Packaging of Flexible MEMS Airflow-Rate Sensor and Its Sensitivity Enhancement

Micro-electro mechanical systems (MEMS) thermal flow sensors have been widely utilized for a wide spectrum of applications. Innovative fabrication processes using polymers have resulted in the development of their flexible alternatives which allowed mounting in a wider range of situations. To accurately measure airflow-rate using a MEMS flow sensor, the airflow region has to be defined and encapsulated. In this study, we propose a facile packaging method of flexible MEMS airflow-rate sensor. The thermal sensing structure was fabricated on a flexible polyimide film. The film was inserted into a resin tube through its taper-cut end and fixed at the center of the tube taking advantage of its buckling. Sensitivity and response speed enhancement were demonstrated by limiting the thermal loss to the substrate by introducing a sensor structure with double-layer substrate.