Maximum Actuation Voltage Research Articles

High‐quality coplanar waveguide tunable band‐stop filter using defected ground structure and comb‐line resonator with radio frequency microelectromechanical system varactors

SummaryA new analog tunable Ka‐band band‐stop filter is proposed on high resistivity silicon (HRS) substrate using radio frequency microelectromechanical systems (RF MEMS) varactors for satellite and radar applications. The designed filter uses a λ/4 comb‐line resonator on the center line of a coplanar waveguide (CPW) with a new uncommon defected ground structure (DGS). Using the DGS in the proposed structure not only decreases the lateral size of the filter but also increases the quality factor. The tuning range of the proposed filter is 29.8–35.6 GHz with a maximum actuation voltage of 44.5 V and a band rejection between 37 and 45 dB. The quality factors of the designed filter in the up and down states of the MEMS varactors are 162 and 292, respectively. The equivalent circuit model of the filter is exactly extracted, and DGS dimensions are optimized. Based on the frequency simulation using ANSOFT HFSS 14, the insertion loss of the designed filter is about 0.51 dB in the 0–20 GHz range and 2 dB in the 0–15 GHz range in, respectively, up and down state of the bridge. The return losses are 0.51 and 0.33 dB at the center frequency for the up‐ and down‐state configuration of the bridge. A step‐by‐step fabrication process is also proposed for designing the band‐stop filter. High quality factor, small size, and improved structure are the advantages of the proposed design.

Hybrid vibration control of a flexible composite box cross-sectional manipulator with piezoelectric actuators

Robotic arms can be produced from composite materials with different cross-sections due to their lightness and high strength properties. The flexibility of robotic arms affects the vibration behavior of robots in engineering applications. The suppression of vibrations increases the dynamic performance of flexible robots. In this study, hybrid vibration control of a smart composite box manipulator (SCBM) is investigated numerically and experimentally. Hybrid vibration control is achieved using passive control (PC) and active control (AC) techniques. The single-axis epoxy glass SCBM has a layer orientation of [0/90/0/90]. The PC is achieved with a trapezoidal velocity profile. Experiments are conducted to verify the simulation results. For AC, the PID control with displacement and strain feedbacks is applied to the SCBM, which is driven with the cases in the PC for further reducing residual vibrations. Simulations are performed by embedding the hybrid control method into the finite element solutions in ANSYS. Controller gains are initially found by the tuning methods and then optimized according to the maximum actuation voltage. The residual vibrations of the composite manipulator have been successfully suppressed for different payloads. The effectiveness of the hybrid control technique on residual vibration results is investigated.

A Compliant MEMS Device for Out-of-Plane Displacements With Thermo-Electric Actuation

A MEMS actuator for micrometric displacements in the out-of-plane direction is proposed in this paper. The device is based on a compliant micromechanism composed of a thick layer of nickel and two thin layers of silicon nitride ensuring displacements in the out-of-plane direction. Its actuation is thermo-electrically performed, the polysilicon resistor encapsulated between the two thin silicon nitride layers is heated by Joule effect; the obtained thermo-mechanical deformation is therefore converted into an out of plane displacement thanks to the compliant mechanism realized in the device structure. The behavior of the device has been analytically modeled through the pseudo-rigid body model methodology and simulated with finite elements models in order to study and optimize its performance. The results coming from the presented models and the device operation have been experimentally validated by characterizing a prototype of this device micro-fabricated in the MetalMUMPs process from MEMSCAP. The maximum displacement of the device is ~16 μm with a maximum actuation voltage of 90 V and the maximum exerted force is ~17 mN.

Intelligent Bipolar Control of MEMS Capacitive Switches

Closed-loop control of microelectromechanical systems (MEMS) capacitive switches was demonstrated by using an intelligent CMOS circuit. The control was based on fine tuning the bias magnitude of the switches according to the difference between sensed and targeted capacitances. Innovative designs were used to allow the CMOS circuit to sense low capacitance and to handle high voltage. The CMOS die of 3 × 1.5 mm2 was dominated by input/output and voltage regulation/protection circuits; the actual capacitance sense/control circuit was smaller than 0.1 mm . The entire circuit consumed 0.7 mW of power during active sense/control, which could be significantly reduced with less frequent sense/control and advanced CMOS technology. With a maximum actuation voltage of ±40 V and a target capacitance of 0.5 pF, a control accuracy of ±2.5% was demonstrated, which could be improved to ±1% with reduced parasitics through monolithic integration. Intelligence was programmed to alternate the bias sign when its magnitude required to maintain the targeted capacitance drifted significantly due to charging of the switch dielectric. Such intelligent control could also be used to compensate for process variation, material creep, ambient temperature change, and RF power loading, which would make MEMS capacitive switches not only more reliable, but also more robust.

Tuneable IR Photodetectors for Spectroscopic Applications

The concept and realisation of infrared micro-spectrometers using MEMS based Fabry-Pérot micro-filters integrated with IR photo-detectors are presented. By using five layer mirror structures, and stress optimisation in mirrors and actuators the tuning range from 1700 nm to 2300 nm has been achieved with maximum actuation voltage of only 18 V RMS. The average FWHM of the transmission peak was measured to be 35 nm, predominantly limited by thickness nonuniformity of individual mirror layers.

Design and fabrication of a single membrane push-pull SPDT RF MEMS switch operated by electromagnetic actuation and electrostatic hold

In this paper, we report a new push-pull-type SPDT (single pole double throw) switch actuated by the combination of electromagnetic and electrostatic forces for low power and low voltage operation. The switch is initially actuated by large electromagnetic force to change its state and is held to maintain its state by applying electrostatic force to reduce static power consumption. The electromagnetic force can be easily generated at low voltage. The maximum actuation voltage is below 4.3 V and the required energy is 15.4 µJ per switching. It achieves signal isolation of −54 dB and insertion loss of −0.16 dB at 2 GHz, respectively. For 20 GHz operation, isolation and insertion loss were measured as −36 dB and −0.52 dB, respectively. The proposed SPDT switch combines two switching elements in a single structure, simplifying the overall structure and control signals and eliminating mismatches between the two switching elements. The dimension of the switch has been optimized using FEM simulation and analytical calculations. We have successfully carried out a lifetime test over more than 166 million cycles with the maximum actuation voltage below 4.3 V.

Actuation potentials and capillary forces in electrowetting based microsystems

The minimum and maximum actuation voltages in electrowetting actuated microsystems are investigated in this paper. The minimum actuation voltage corresponds to the electric potential required to obtain motion of a droplet between two electrodes. Below this threshold, a droplet cannot be displaced due to contact angle hysteresis. The maximum actuation voltage corresponds to the electric potential above which there is no more gain in capillary forces because of the saturation effect. Based on the calculation of the electrocapillary forces on a drop in an EWOD system, and taking into account the contact angle hysteresis, an analytical relation is derived for the minimum actuation potential. On the other hand, the Peykov–Quinn–Ralston–Sedev model produces an approximate value of the maximum actuation voltage. Thus, a range of actuation potentials can be predicted depending on the liquid of the droplet, the surrounding gas or fluid and the nature of the solid substrate. The results of the two models are favorably compared with experimental results obtained using different liquids and substrates.

Design and characterization of adaptive microbolometers

We report the first practical results on design and characterization of adaptive microbolometers with a thermally tuned responsivity. Such devices are needed to simultaneously image scenes that contain objects at ambient and extremely hot temperatures. In the high detectivity state, the microbolometers are operated similar to standard commercial devices. In the low detectivity state, portions of the support beams are brought in contact with the substrate, which thermally shorts the devices on a pixel-by-pixel basis. This is the first time this concept has been practically implemented in a microbolometer device architecture as opposed to simple cantilever beams and plates. The maximum actuation voltage is set to 17 V, and the thermal conductances, responsivities and detectivities of a typical device can be switched more than an order of magnitude between 1.65 × 10−5 W K−1 and 2.99 × 10−4 W K−1, between 1.5 V W−1 and 0.2 V W−1 and between 1.8 × 106 cm Hz1/2 W−1 and 1.5 × 105 cm Hz1/2 W−1, respectively. This extends the dynamic range of the device more than an order of magnitude. The device pixel size is 100 µm ×100 µm.

Design and nonlinear servo control of MEMS mirrors and their performance in a large port-count optical switch

In this paper, we demonstrate full closed-loop control of electrostatically actuated double-gimbaled MEMS mirrors and use them in an optical cross-connect. We show switching times of less than 10 ms and optical power stability of better than 0.2 dB. The mirrors, made from 10-/spl mu/m-thick single-crystal silicon and with a radius of 400-450 /spl mu/m, are able to tilt to 8/spl deg/ corresponding to 80% of touchdown angle. This is achieved using a nonlinear closed-loop control algorithm, which also results in a maximum actuation voltage of 85 V, and a pointing accuracy of less than 150 /spl mu/rad. This paper will describe the MEMS mirror and actuator design, modeling, servo design, and measurement results.

Use of polymer and ceramic thin film materials to reduce the actuation voltage of adistributed micro-electromechanical system phase shifter

An improved design for a distributed micro-electromechanical system phase shifter,periodically loaded with polymer bridges, is presented in this note. The phase shifter,fabricated on a quartz substrate, is capable of continuous change in phase up to about90° (at 15 GHz) with a maximum actuation voltage of 20 V. Modifications in the present designinclude the use of a dielectric layer to prevent breakdown as well as to reduce the actuationvoltage requirement, and a reduction in the bridge height and thickness. It has been shownthat polymer materials by themselves can reduce the actuation voltage due to their lowYoung’s modulus.