MEMS wind direction detection: from design to operation

A multi-axis hotwire anemometer fabricated with bulk micro-machining and thin film semiconductor technologies is presented. Extending the operation of a single axis anemometer into 2 axes allows direction sensing over the full 0° - 360° while maintaining the original ability to measure flow velocity via the forced convection heat loss. Eliminating separate heating and sensing elements and combining both functions into single element pairs provides a means of lowering the temperature and power requirements and reducing size and fabrication complexity of the sensor compared to previously seen designs. CAD and modeling have aided in preparation of a suitable design to be fabricated in house using primarily photolithography and wet chemical etching. Successful wind tunnel trials have paved the way for field-testing and a commercially realizable sensor.