High temperature gradient micro-sensor for wall shear stress and flow direction measurements
Micro-capteur à fort gradient de température pour des mesures de frottement pariétal et de direction de l'écoulement
Résumé
We present an efficient and high-sensitive thermal micro-sensor for near wall flow parameters
measurements. By combining substrate-free wire structure and mechanical support using silicon
oxide micro-bridges, the sensor achieves a high temperature gradient, with wires reaching 1 mm
long for only 3 µm wide over a 20 µm deep cavity. Elaborated to reach a compromise solution
between conventional hot-films and hot-wire sensors, the sensor presents a high sensitivity to the
wall shear stress and to the flow direction. The sensor can be mounted flush to the wall for research studies such as turbulence and near wall shear flow analysis, and for technical applications, such as flow control and separation detection. The fabrication process is CMOS-compatible and allows on-chip integration. The present letter describes the sensor elaboration, design, and micro-fabrication, then the electrical and thermal characterizations, and finally the calibration experiments in a turbulent boundary layer wind tunnel.
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