Self Heated Thermo-Resistive Element Hot Wire Anemometer





A microelectromechanical systems (MEMS) hot wire anemometer consisting of thermoresistive elements arranged in a differential bridge configuration is presented. The excitation of the elements to the point of self heating allows for dedicated heating elements to be omitted from the device without compromising operation or accuracy. Overall power consumption gives air velocity, and the temperature differential of each element pair is used for wind direction calculation and has demonstrated a sensing resolution better than 1% and a repeatability better than 2%.

A bulk machined dual axis hot wire anemometer consisting of four thermoresistive elements arranged in a differential bridge configuration is presented. Where heating elements are often used on such devices [1], the sensor discussed here uses self heating of the thermoresistive sensing elements to provide the thermal energy required to generate the thermal plume and temperature differential across the surface of the device. The central heating elements used on typical integrated hotwire anemometers [2]–[4] use valuable real estate on the die and adds complexity and potential failure mechanisms to the design. Removal of the central heating element(s) reduces the number of elements that must be interfaced and frees up silicon real estate for other purposes, such as other sensing arrays

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