RF MEMS Switch on Poly-Silicon Substrate

The improvements of the design and the compatibility with silicon IC of RF MEMS switch are presented.The compatibility with silicon IC is realized by dielectric isolation technology,and the decrease of the pull voltage of the switch is done by etching some holes on the metal membrane.The preliminary test results are as follows: C off and C on are 0 32pF,6pF,respectively;the pull down voltage is about 25V.The package of the RF MEMS switch is done by micro stripline,and the isolation and the insertion loss are 35dB,2dB,respectively at 1 5GHz;the switching speed is about 3μs by oscilloscope.

Growth of ZnO self-converted 2D nanosheet zeolitic imidazolate framework membranes by an ammoniaassisted strategy

Shaping crystalline porous materials such as metal organic frameworks （MOFs） and zeolites into two-dimensional （2D） nanosheet forms is highly desirable for developing high-performance molecular sieving membranes. However, conventional exfoliation-deposition is complex and challenging for the large-scale fabrication of nanosheet MOF tubular membranes. Here, for the first time, we report a direct growth technique by ZnO self-conversion and ammonia assistance to fabricate zeolitic imidazolate framework （ZIF） membranes consisting of 2D nanosheets on porous hollow fiber substrates; the membranes are suitable for large-scale industrial gas separation processes. The proposed fabrication process for ZIF nanosheet membranes is based on the localized self-conversion of a pre-deposited thin layer of ZnO in a ligand solution containing ammonium hydroxide as a modulator. The resulting ZIF 2D nanosheet tubular membrane is highly oriented and only 50 nm in thickness. It exhibits excellent molecular sieving performance, with high H2 permeance and selectivity for H2/CO2 separation. This technique shows great promise in MOF nanosheet membrane fabrication for large-scale molecular sieving applications.

A Facile Method for Dye and Heavy Metal Elimination by p H Sensitive Acid Activated Montmorillonite/Polyethersulfone Nanocomposite Membrane

Modified clay/polyethersulfone（PES） mixed matrix membranes（MMMs） were prepared by acid activated montmorillonite（AA-MMT） with different concentrations and used to eliminate dyes and remove heavy metals from aqueous solution. The morphology and physiochemical properties of prepared clay nanoparticles and MMMs were characterized using X-ray diffraction（XRD）, Fourier transform infrared（FTIR） spectroscopy, scanning electron microscopy（SEM）, enegy dispersive X-ray（EDX） spectroscopy, Brunauer-Emmett-Teller（BET） analysis, atomic force microscopy（AFM）, contact angle measurement and fouling studies. The filtration study showed that removal of dyes and heavy metals was strongly dependent on p H so that dyes with positive and negative charges showed different separation efficiency in acidic and alkaline conditions. The modified membranes possessed better heavy metal removal in acidic and alkaline p Hs. When the rejection of heavy metals was measured in an alkaline environment, it was observed that the rejection had a great increase compared to the neutral values for Zn^（2＋） and Ni^（2＋） ions, while rejection of Cu^（2＋） and Cd^（2＋） did not undergo significant changes. So it can be concluded that modified membranes show good selectivity for elimination of Zn^（2＋） and Ni^（2＋） ions with respect to other cations.