Antenna miniaturization technology has been a challenging problem in the field of antenna design. The demand for antenna miniaturization is even stronger because of the larger size of the antenna in the low-frequency band. In this paper, we consider MEMS magnetoelectric antennas based on mechanical resonance, which sense the magnetic fields of electromagnetic waves through the magnetoelectric (ME) effect at their mechanical resonance frequencies, giving a voltage output. A 70 μm diameter cantilever disk with SiO2/Cr/Au/AlN/Cr/Au/FeGaB stacked layers is prepared on a 300 μm silicon wafer using the five-masks micromachining process. The MEMS magnetoelectric antenna showed a giant ME coefficient is 2.928 kV/cm/Oe in mechanical resonance at 224.1 kHz. In addition, we demonstrate the ability of this MEMS magnetoelectric antenna to receive low-frequency signals. This MEMS magnetoelectric antenna can provide new ideas for miniaturization of low-frequency wireless communication systems. Meanwhile, it has the potential to detect weak electromagnetic field signals.
The aspect ratio of nanostructures determines the mechanical sensitivities and responses, such as hydrodynamic and oscillating flow detection. Nanopillar arrays with ultrahigh aspect ratio were fabricated using deep reactive-ion etching (DRIE) based on the optimized parameters in this study. Wafer-scale nanopatterning was achieved using dislocation lithography with normal photolithography machine instead of e-beam or EUVL. The wafer-scale Cr masks with 300, 500, and 700 nm line arrays were successfully patterned on silicon, providing etching mask for the fabrication of nanopillar arrays with a high aspect ratio. The important limitation of undercut during DRIE was solved by modifying the process parameters and using double masks composed of photoresist and Cr. Finally, the aspect ratio of the silicon nanopillar array reached 120 with smooth surface and vertical sidewalls. The methodology can provide a general approach for fabricating complex 3D periodic nanostructures that can be applied to various fields of multifunctional detection applications to increase detection probability and sensitivity.
This paper presents a guided-mode resonance (GMR) reflector for sapphire based Fabry-Perot (F-P) sensors that enables tunable or wideband high reflectance with high temperature resistance, which is expected to effectively regulate the performance of F-P sensors and offer a novel approach for designing F-P sensors in harsh environments. Intrinsic and extrinsic GMR gratings are proposed, and their optical and thermal properties are investigated and compared through numerical simulations, such as rigorous coupled-wave analysis and finite element analysis methods. The quantitative results indicate high feasibility for harsh environment applications and the potential for adopting different demodulation methods. Significant enhancement in the F-P sensor performance is obtained through analysis based on the F-P interference model, and the spectrum fineness and sensor sensitivity can be enhanced by at least one order of magnitude. The GMR reflector can be extended to other types of F-P sensors, demonstrating significant potential in high-temperature applications.
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