2D Calorimetric Thermal Flowmeter with Integrated Thermal Conductivity Sensor

This paper reports on a 2D calorimetric thermal flowmeter with integrated thermal conductivity sensing. The sensor consists of a membrane of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$3\text{mm}\times 3\text{mm}$</tex> with a central heater, surrounded by thermal sensors. The flowrate and flowdirection are measured by measuring the temperature difference of sensors on opposing sides of the heater. The thermal conductivity is measured, independent of flow or direction, by measuring the temperature gradient around the heater. Measurement and simulation are in good agreement for flowrates up to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$11_{\mathrm{n}}/\min$</tex> for nitrogen, argon and helium.