A Monolithically Integrated 3D Wind Sensor with Low Crosstalk Based on a Three-Level Cascade Mechanism

This study presents a monolithically integrated three-dimensional (3D) wind sensor with a low-crosstalk characteristic based on a three-level cascade mechanism for the first time. A center platform for loading a cilium is serially supported by three sets of torsion bars, which are orthogonally configured by utilizing two gimbals. A cilium together with the platform will independently rotate along the X and Y torsion bars by sensing the in-plane wind. The entire suspended platform can sufficiently sense the out-ofplane wind and the downward movement will make the Z torsion bars rotation. This three-level cascade mechanism can achieve superior decoupling characteristics among three axes. Three silicon-based piezoresistive Wheatstone bridge sensors are located at the torsion-bar roots to linearly sense the rotation angles, which are relating to the wind speeds. Wind tunnel tests demonstrate its superior characteristics of the high sensitivities of 0.26,0.22, and 0.06 mV /(m/s)/V in the X, Y, and Z directions, with the corresponding root mean square (RMS) errors of 0.05, 0.08, and 0.28 m/s, respectively. The crosstalk between the X and Y axes is minimal, with a value of ≤ 1.2 m/s. Although the coupling along the Z -axis is relatively higher at 6.6 m/s, the sensor still achieves reliable and independent three-dimensional detection. The demonstrated cascadedgimbal architecture offers a compact and integrable solution for 3D wind-field sensing, with potential for unmanned aerial vehicle (UAV) wind-field mapping and future array-level flow-field measurement.