Multi-parameter sensing with a thermal silicon flow sensor

We present a method for multi-parameter sensing in the application of thermal vector flow sensors. The method is based on the property that two independent signals can be obtained from a single sensing element, viz. a thermal vector flow sensor. For particular applications, this reduces the number of sensors in the measurement process. It may also allow redundant measurement of physical parameters, such as temperature; these redundant measurements are important for self-diagnostics of proper operation of a measurement system. The method is applied to a bidirectional silicon flow sensor, that generates two independent signals, both being a function of the Re number and the fluid temperature. This allows both temperature and mass flow measurement by use of a single sensor. Temperature estimates are accurate within 0.64 K and mass flow estimates within 5.6%.