Micromachined structures for thermal measurements of fluid and flow parameters

In this paper thermal sensor-actuator structures are proposed that can be u sed to measure various fluid parameters such as thermal conductivity, flow velocity, heat capacity, kinematic viscosity and pressure. All structures a re designed in such a way that they can be realized in the same fabrication process and therefore they can be easily combined in a single device. All structures are based on the principle of thermal measurements: resistive st ructures are used for both heating and temperature measurements. For accura te measurements the temperature coefficient of resistance (TCR) must be wel l known. Therefore, a special structure, which can be used for auto-calibra tion, was designed to measure the TCR. A first device containing structures for the combined measurement of flow velocity, thermal conductivity and TC R has been fabricated. Measurements show promising results.