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In this paper, the design, fabrication, and characterization of a robust MEMS thermal wind sensor utilizing ceramic film packaging are proposed. The ceramic film is fabricated by means of low temperature co-fired ceramic (LTCC) technology, achieving the excellent adhesion between silicon substrate and ceramic film without any thermal adhesive. The most important is that the adverse effects of the packaging on the performance of the thermal wind sensor can be minimized by adjusting the thickness and thermal conductivity of the ceramic film during the preparation of the ceramic slurry. The influences of thickness and thermal conductivity of ceramic film on the performance of sensor have been simulated by finite element method, and the results are in reasonable agreement with theoretical analysis. The proposed sensors were tested and calibrated in a wind tunnel. Experiments results demonstrate that the sensitivity of the proposed sensor is decreased only 4.7%, compared with the sensor without ceramic film. The maximum measurement error of the proposed sensor in wind speed and direction is 0.66 m/s and 5°, respectively. Compared with the sensor packaged with $250\mu \text{m}$ ceramic carrier, the heating power of the proposed sensor is reduced by nearly 50% and the sensitivity is increased by an order of magnitude at the same time. [ABSTRACT FROM AUTHOR]

A self-heated double Wheatstone bridge configuration for a 2-D wind sensor is presented. Without a central heating element, eight thermistors are symmetrically arranged in two orthogonal directions, and four of them in each direction make up a Wheatstone bridge. The eight thermistors simultaneously act as the heating sources and temperature sensing elements. By applying the constant current supply to the bridge, the terminal voltage across the bridge and the bridge output voltage are utilized to measure the wind speed and direction, respectively. The 2-D wind sensor has been simulated numerically and fabricated directly on the ceramic substrate. Experiments demonstrate that the measured speed varies from 0 to 40 m/s with an error less than ±2 m/s while the measured direction spans from 0° to 360° with an error less than ±3° after calibration. The double bridge configuration greatly simplifies the measurement and control circuits for the 2-D wind sensor. [2018-0171] [ABSTRACT FROM AUTHOR]

In this paper, we present a robust, low-power and wide-range MEMS thermal wind sensor, which is based on a glass reflow process. A general analytical model is first proposed for obtaining the heater's temperature and the temperature distribution on the sensor surface. Based on this model, the effect of the sensor's geometry and package on the sensor's performance is investigated. These results demonstrate how the measurement range and the sensitivity of the sensor can be optimized with a change in structural geometries. Besides, it has shown that the package structure of the sensor is also important for obtaining the required performance. Then, calculated results are validated with 2-D finite element method (FEM) solver CMOSOL. It is found that although there is some deviation between theoretical and simulation results, the model can have good reference value for latter MEMS thermal wind sensor design. Finally, the sensor is characterized in a wind tunnel. At a constant heating power of 14.5 mW, measurement results show that the sensor can detect airflow speeds of up to 33 m/s, with an accuracy better than 0.5 m/s at low speeds and 5% Full-Scale at high speeds. Airflow direction can be determined in a 360° range with an accuracy better than 5°. In addition, the sensor also shows a good repeatability. [ABSTRACT FROM AUTHOR]