A self-packaged two-dimensional thermal wind sensor based on thermopiles for low cost applications

In this paper, the design, fabrication and characterization of a low cost micro-machined two-dimensional (2D) wind sensor using thermopiles fabricated on ceramic substrate as sensing elements are presented for the first time. In the sensor, the nickel heaters and four nickel (Ni)/aluminum (Al) thermopiles were directly fabricated on the front surface of the ceramic plate while the back side, as the sensing surface, was exposed to the wind. The whole process is simple and only needs three masks. The sensor substrate is used directly as a packaging board for sensing wind with no need of an extra packaging plate, which is called a self-package. This method reduces the deviation caused by the chip packaging process and has a low manufacturing cost. In order to improve the performance of the wind sensor, modeling and simulation were also performed. Based on the simulation results, the effects of chip size, heater length and heating power on the sensitivity and measurement range of the thermal wind sensor was investigated. The sensor was tested in a wind tunnel in constant power (CP) mode. Measurement results show that the thermal wind sensor can measure wind speeds up to 30 m s(-1) and wind direction in a full range of 360 degrees. The proposed sensor can be used for low cost applications with a certain accuracy.