MEMS-based Filter Research Articles

Simulation and Analysis of Anodized Aluminum Oxide Membrane Degradation.

Microelectromechanical systems (MEMS)-based filter with microchannels enables the removal of various microorganisms, including viruses and bacteria, from fluids. Membranes with porous channels can be used as filtration interfaces in MEMS hemofilters or mini-dialyzers. The main problems associated with the filtration process are optimization of membrane geometry and fouling. A nanoporous aluminum oxide membrane was fabricated using an optimized two-step anodization process. Computational strength modeling and analysis of the membrane with specified parameters were performed using the ANSYS structural module. A fuzzy simulation was performed for the numerical analysis of flux through the membrane. The membrane was then incorporated with the prototype for successive filtration. The fluid flux and permeation analysis of the filtration process have been studied. Scanning electron microscope (SEM) micrographs of membranes have been obtained before and after the filtration cycles. The SEM results indicate membrane fouling after multiple cycles, and thus the flux is affected. This type of fabricated membrane and setup are suitable for the separation and purification of various fluids. However, after several filtration cycles, the membrane was degraded. It requires a prolonged chemical cleaning. High-density water has been used for filtration purposes, so this MEMS-based filter can also be used as a mini-dialyzer and hemofilter in various applications for filtration. Such a demonstration also opens up a new strategy for maximizing filtration efficiency and reducing energy costs for the filtration process by using a layered membrane setup.

A chip-scale frequency down-conversion realized by MEMS-based filter and local oscillator

A wide-width clamped-clamped beam (CC-beam) resonator and a filter realized using mechanically-coupled resonator tanks have been extensively characterized to attain mixler (i.e., mixer-filter) functionality for a chip-scale frequency translation. Such a resonator has been driven into the nonlinear regime to explore its effect on the mixler operation as well as to obtain the best phase noise performance using the phase-feedback method. The proposed electrostatically transduced mixler operates by utilizing the local oscillator (LO) signal generated from the resonator itself, thus eliminating the need of a function generator or an external quartz crystal oscillator. This technique implemented with all the components on the same silicon substrate shows great potential for miniaturization in wireless communication while achieving 14.4 dB overall mixler loss.

MEMS-based filter integrating tunable Fabry–Perot cavity and grating

We present a novel Micro-Electro-Mechanical-Systems (MEMS) filter integrating a tunable Fabry–Perot cavity and a grating (FP-G). It fuses the functions of the Fabry–Perot (FP) cavity and grating into a single device so as to realize both narrow spectral linewidth given by FP cavity and wide spectral range given by grating. A MEMS FP-G filter with 200μm cavity length was designed and fabricated. It is based on a W-shaped-section micro-bridge structure by which the electrostatic actuator is independent on the FP cavity and a long cavity length can be configured. A grating etched in the back of a cavity mirror serves to spatially separate the transmitted spectral lines corresponding to different interference orders of FP cavity. Experimental results indicated that the MEMS FP-G filter obtained a broader operation spectral range compared with the traditional MEMS FP filter, and achieved 1.2 nm spectral linewidth, which could be narrower by improving the effective finesse of the FP cavity in the fabrication process. Compared with the simulation results, there was considerable room for improvement in device performance by the optimal technique.

MEMS-based 14 GHz resolution dynamic optical filter

A 64-channel 14 GHz-spaced MEMS-based filter with flat-top passbands and 7 dB insertion loss has been constructed. It utilises a lens and grating to demultiplex the light onto an array of electrostatically actuated micromechanical single axis tilt mirrors.