A smart 2-D wind sensor with self-test function

A 2-D smart wind sensor with self-testing function was designed, fabricated and tested in this paper. It is composed of cross-structure heaters and four symmetrically located sensing parts. When the flow angle changes clockwise, the temperature differences among the four parts, namely T₁₃ (T₂₄) and T₁₂ (T₁₄) will be sine (cosine) functions of wind direction. Further study shows that the amplitudes of T₁₃ and T₂₄ are radic2 times of T₁₂ and T₁₄, and the phases are 45 degree before the latter. Then two wind direction values can be obtained for self-test without additional components. In order to achieve moderate sensitivity without post-MEMS etching, thermal insulated substrate was introduced to fabricate calorimetric flow sensor instead of silicon wafer. The proposed sensor was fabricated on the low thermal conduction substrate Pyrex7740 using single lift-off process. Finally, wind tunnel test was carried out in constant power (CP) mode, and the test results show reasonable agreement with the simulation results.