Novel flow sensors based on a two-state controller scheme

We present a novel control loop scheme for calorimetric flow sensors combining an electronic two-state controller with the electro-thermal transduction system. Such on-off control schemes can be optimized for a specified flow range and by that outperform classical analogue controllers. For a convenient controller design, we developed a comprehensive SPICE model of the thermal system able to fully cover its static and dynamic behavior. The thermal system was characterized experimentally and investigated by finite element analysis software (COMSOL) in order to extract relevant SPICE model parameters. Experiments confirm that this approach enables the implementation of optimized controllers for any calorimetric flow transducer and specific measurement tasks.