The design, simulation, fabrication, and experiments of a novel flow sensor based on resonant sensing with a two-stage microleverage mechanism are presented in this paper. Different from the conventional detection methods for flow sensors, two differential resonators are adopted to implement air flow rate transformation through two-stage leverage magnification. The proposed flow sensor has a high sensitivity since the adopted two-stage microleverage mechanism possesses a higher amplification factor than a single-stage microleverage mechanism. The modal distribution and geometric dimension of the two-stage leverage mechanism and hair are analyzed and optimized by Ansys simulation. A digital closed-loop driving technique with a phase frequency detector-based coordinate rotation digital computer algorithm is implemented for the detection and locking of resonance frequency. The sensor fabricated by the standard deep dry silicon on a glass process has a device dimension of 5100 μm (length) × 5100 μm (width) × 100 μm (height) with a hair diameter of 1000 μm. The preliminary experimental results demonstrate that the maximal mechanical sensitivity of the flow sensor is approximately 7.41 Hz/(m/s)² at a resonant frequency of 22 kHz for the hair height of 9 mm and increases by 2.42 times as hair height extends from 3 mm to 9 mm. Simultaneously, a detection-limit of 3.23 mm/s air flow amplitude at 60 Hz is confirmed. The proposed flow sensor has great application prospects in the micro-autonomous system and technology, self-stabilizing micro-air vehicles, and environmental monitoring.

Broadband anti-reflection (AR) coatings are essential elements for improving the photocurrent generation of photovoltaic modules and enhancing visibility in optical devices. In this paper, we report a hybrid-structured, anti-reflection coating that combines multi-layer thin films with a single top-oblique deposited layer. By simply introducing this low-refractive index layer, the broadband anti-reflection properties of optical thin films can be improved while simplifying the preparation. Precise time-controlled and oblique-angle deposition (OAD) methods were used to fabricate the broadband AR coating. By accurately measuring and adjusting the design errors for the thin and thick film layers, 22-layer and 36-layer AR coatings on a sapphire substrate with a 400–2000 nm wideband were obtained. This bottom-up preparation process and AR coating design have the potential to significantly enhance the broadband antireflective properties for many optical systems and reduce the manufacturing cost of broadband AR coatings.

The design, analysis, and simulation of a new Micro-electromechanical System (MEMS) gyroscope based on differential tunneling magnetoresistance sensing are presented in this paper. The device is driven by electrostatic force, whereas the Coriolis displacements are transferred to intensity variations of magnetic fields, further detected by the Tunneling Magnetoresistance units. The magnetic fields are generated by a pair of two-layer planar multi-turn copper coils that are coated on the backs of the inner masses. Together with the dual-mass structure of proposed tuning fork gyroscope, a two-stage differential detection is formed, thereby enabling rejection of mechanical and magnetic common-mode errors concurrently. The overall conception is described followed by detailed analyses of proposed micro-gyroscope and rectangle coil. Subsequently, the FEM simulations are implemented to determine the mechanical and magnetic characteristics of the device separately. The results demonstrate that the micro-gyroscope has a mechanical sensitivity of 1.754 nm/°/s, and the micro-coil has a maximum sensitivity of 41.38 mOe/µm. When the detection height of Tunneling Magnetoresistance unit is set as 60 µm, the proposed device exhibits a voltage-angular velocity sensitivity of 0.131 mV/°/s with a noise floor of 7.713 × 10⁻⁶°/s/$\sqrt{\mathrm{Hz}}$ in the absence of any external amplification.

A digital excitation-calibration technique of dual-mass MEMS gyroscope for closed-loop mode-matching control is presented in this paper. The technique, which takes advantage of the symmetrical amplitude response of MEMS gyroscope, exploits a two-side excitation signal to actuate the sense mode to obtain the corresponding DC tuning voltage. The structural characteristics of dual-mass decoupled MEMS gyroscope and the tuning principle of excitation-calibration technique are introduced firstly. Then, the scheme of digital excitation-calibration system for the real-time mode-matching control is presented. Simultaneously, open-loop analysis and closed-loop analysis are deduced, respectively, to analyze the sources of tuning error and system stability. To verify the validity of the scheme and theoretical analysis, the system model was established by SIMULINK. The simulation results are proved to be consistent with the theoretical analysis, verifying the feasibility of the digital excitation-calibration technique. The control algorithms of the system were implemented with a FPGA device. Experimental results demonstrate that digital excitation-calibration technique can realize mode-matching within 1 s. The prototype with real-time mode-matching control has a bias instability of 0.813 ${}^{\circ }$ /h and an ARW (Angular Random Walk) of 0.0117 ${}^{\circ }$ / $\sqrt{h}$ . Compared to the mode-mismatching condition, the bias instability and ARW are improved by 3.25 and 4.49 times respectively.

This paper presents the design, theoretical analysis, simulation verification, fabrication and prototype characterization of a novel biaxial bionic hair flow sensor based on resonant sensing. Firstly, the device architecture, mainly consists of a polymer hair post, a silicon micro signal transducer and a glass substrate, is described, the theoretical simplified model is established and the mechanical sensitivity to air flow is deducted. Then, the structure simulations based on Ansys software are implemented to preliminarily verify the feasibility of the proposed sensor conception and optimize the structure parameters simultaneously. Subsequently, a closed-loop control scheme based on digital phase-locked loop and an amplitude demodulation algorithm of oscillatory flow velocity based on the least mean square method are proposed to transform and extract the air flow signal, and then verify it by circuit simulations based on SIMULINK. Finally, the fabricated prototype is illustrated and comprehensively tested. The tested prototype possesses an x-axis scale factor of 1.56 Hz/(m/s)² and a y-axis scale factor of 1.81 Hz/(m/s)² for the steady air flow and an x-axis detection threshold of 43.27 mm/s and a y-axis detection threshold of 41.85 mm/s for the oscillatory air flow.