Multicontact MEMS relays laterally actuated using electrostatic comb-drive actuators are reported. The relay consists of a movable main beam anchored to the substrate using two identical folded suspension springs. Multicontact RF ports consist of five movable fingers connected to the movable main beam and six fixed fingers anchored to the substrate. Comb-drive actuators located at the top and bottom ends of the main beam enable bidirectional actuation of the RF contacts. The MEMS relays were fabricated using the MetalMUMPs process, which uses 20-µm-thick electroplated nickel as the structural layer. A 3-µm-thick gold layer was electroplated at the electrical contact surfaces. An example MEMS relay with planar contacts of area 80 µm×20 µm and a spacing of 10 µm between the movable and fixed contacting surfaces is discussed. The overall size of the relay is approximately 3 mm×3 mm. "Resistance versus applied voltage" characteristics of the MEMS relay have been measured for applied DC bias voltages in the range of 172 V to 220 V. A multiscale rough surface contact model was used to estimate the actual electrical contact resistance versus applied force curve of these devices. The multiscale model showed good qualitative agreement with the experimental measurements but requires more refinement to achieve good quantitative agreement.
Reliability of electrostatically actuated ohmic contact type MEMS relays has been investigated. Multi-contact MEMS relays using electrostatic comb-drive actuators has been used in this study. The MEMS relays were fabricated using MetalMUMPs process, which uses 20 μm thick electroplated Nickel as the structural layer. A 3 μm thick gold layer was electroplated at the electrical contact surfaces. The overall size of the relay is approximately 3 mm x 3 mm. The relay consists of a movable main beam anchored to the substrate using two identical folded suspension springs. RF ports consist of five movable fingers connected to the movable main beam and six fixed fingers anchored to the substrate. Comb-drive actuators located at the top and bottom ends of the main beam enable bi-directional actuation of the RF contacts. An example MEMS relay with planar contacts of area 80 μm x 20 μm and a spacing of 10 μm between the movable and fixed contacting surfaces is discussed. Resistance versus applied voltage characteristics has been studied. For an applied DC bias voltage of 172 V, the movable fingers make contact with the fixed fingers. The resistance versus applied voltage characteristics has been measured for an applied bias voltage in the range of 172 V to 220 V. A multiscale rough surface contact model was used to estimate the actual electrical contact resistance versus applied force curve of these devices. Reliability testing has been carried out and the resistance variation of the MEMS relay over 80 x 105 actuation cycles has been measured.
This paper reports a MEMS-based electrostatically tunable microstrip patch antenna fabricated using printed circuit processing techniques. The microstrip patch is patterned on the top side of the flexible kapton polyimide film, which is suspended above the fixed ground plane using a spacer. The air gap between the microstrip patch and the ground plane is decreased by applying a DC bias voltage between the patch and the ground plane. A decrease in air gap increases the effective permittivity of the antenna resulting in a downward shift in the resonant frequency. The microstrip patch is excited by a slot in the ground plane, which is inductively coupled by a coplanar waveguide (CPW) feed line. A 6 mm x 6 mm microstrip patch antenna tunable from 18.34 GHz at 0 V to 17.95 GHz at 268 V (with a tuning range of 390 MHz) is discussed.
Micro Electro-Mechanical Systems (MEMS) based capacitive pressure sensors are typically fabricated using silicon micromachining techniques. In this paper, novel Liquid Crystal Polymer (LCP) based capacitive pressure sensors, fabricated using printed circuit processing techniques, are reported. LCP exhibits good dimensional stability, material flexibility, high chemical resistance, and extremely low moisture absorption, which make it suitable for MEMS applications. Each sensor consists of an LCP substrate, an LCP spacer layer with circular holes, and top LCP layer. The portion of the top LCP layer located above the circular hole of the spacer layer serves as the circular diaphragm of the pressure sensor. A typical pressure sensor with a diaphragm radius of 1.6 mm provides a net capacitance change of 0.18 pF for an applied pressure in the range of 0-70 kPa. Hundreds of such sensors can be batch fabricated cost effectively using existing flexible printed circuit technology.
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