Thermal characterisation of a direction dependent flow sensor

• Published in: Sensors and actuators. A. Physical. Vol. 115; no. 2; pp. 417 - 423
• Main Authors: Furjes, P, Legradi, G, Ducso, Cs, Aszodi, A, Barsony, I
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 21.09.2004
• Subjects: Calorimetric gas flow sensor; Micro-channels; Thermal simulation; Micro-channels; Calorimetric gas flow sensor; Thermal simulation
• ISSN: 0924-4247; 1873-3069
• DOI: 10.1016/j.sna.2004.04.050

A calorimetric sensor for detection of gas velocity and flow direction was constructed by sacrificial porous silicon micromachining technique. The sensing element contains four temperature sensing resistors arranged symmetrically around a central filament heater. Finite volume flow simulations (FVM) for velocity vector and temperature distribution around the system elements led to the conclusion that the laminar flow conditions, essential for accurate calorimetric sensing, can be maintained by adequate selection of device dimensions and channel depth. Predictions by the flow and thermal simulations were aimed at defining the optimum geometric design. The results of functional tests performed on the fabricated structure were interpreted in terms of changes of parameters in the thermal equivalent circuit of the device.