Design, modeling and theoretical analysis of a novel dual-axis hair flow sensor based on mode localization of weakly coupled resonators

This paper presents the design, modeling and theoretical analysis of a novel dual-axis hair flow sensor (DHFS) based on the mode localization of weakly coupled resonators (WCRs). A stereoscopic hair post is adopted to interact with external fluid and transmit the air flow velocity signal. Two-stage micro-leverage mechanisms are designed and optimized to amplify the drag force derived from external air flow. As the main sensitive elements, four optimized WCRs are symmetrically distributed around the main frame. A simplified theoretical model of DHFS is established and verified by comprehensive finite element method (FEM) simulations. Unlike the traditional frequency detection method, the presented DHFS detects the air flow velocity by measuring the amplitude ratio shift of two degree of freedom WCRs. The input-output response simulations demonstrate that the presented DHFS exhibits an x-axis sensitivity of 6.5026×10-2/(m/s)2 and a y-axis sensitivity of 6.4527×10-2/(m/s)2. In addition, the simulated relative shift in amplitude ratio (∼65000 ppm/(m/s)2) is three orders of magnitude larger than that in resonance frequency (∼50 ppm/(m/s)2). Meanwhile, the cross-axis sensitivities are 6.4387×10-4/(m/s)2 (x-axis) and 6.4475×10-4/(m/s)2 (y-axis), respectively. In summary, the feasibility of proposed structure architecture and operation principle is verified.