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Measurements of voltage and current transients of a scaled model of an electrostatic microactuator have been performed. Experiments were made at a variety of values of the actuation source resistance, and the effects on the pull-in time and on the energy consumed in a switching event were analysed. It is concluded that the pull-in time remains sensibly constant until source resistance values are reached corresponding more closely to current-controlled than to voltage-controlled actuation. Furthermore, the energy consumed per switching event monotonically decreases with increasing source resistance. There is an optimum source resistance at which a minimum can be found for the product of pull-in time and energy in agreement with earlier theoretical predictions. The experimental results are quantitatively compared with Saber simulations incorporating an analog hardware description language model for the actuator.

10 years ago, the concept of special CAD systems for microsensors and microactuators was proposed at Transducers '87. We now look back over this 10-year period, and examine major trends and accomplishments. Modeling at the system level has grown dramatically, and major advances have been made in the design and simulation of electrostatic actuators and in coupled fluid/structure modeling. Of the many challenges that remain, two appear most significant. The first is the critical step of connecting the behavior of the continuum, as expressed in highly meshed simulations, to equivalent lumped models that can be used efficiently for system-level design and modeling. The second is the incorporation of non-steady-state dissipative behavior into this modeling environment, without having to make unacceptably inaccurate simplifications.

Technologies for fabricating a variety of MEMS devices have developed rapidly, but computational tools that allow engineers to quickly design and optimize these micromachines have not kept pace. Inadequate simulation tools force MEMS designers to resort to physical prototyping. To realistically simulate the behavior of complete micromachines, algorithmic innovation is necessary in several areas.

The response of polymer-coated surface acoustic wave (SAW) devices to temperature changes and polymer vapor absorption is examined. A perturbational approach is used to relate velocity and attenuation responses to film translational and strain modes generated by the SAW. Two distinct regimes of film behavior arise, causing different SAW responses. For glassy films, displacement is nearly uniform across the film thickness, varying only in the direction of propagation. A model developed to predict velocity and attenuation in this regime (model 1), reduces to the familiar Tiersten (Wohltjen) equation for purely elastic films. For elastomeric (rubbery) films, inertial effects cause a phase lag to occur across the film for shear displacements. A model to account for these cross-film displacement gradients (model 2) predicts a characteristic resonant response when the film phase shift reaches n[pi]/2, where n is an odd integer. These model predictions are compared with measured responses from polyisobutylene-coated SAW devices as temperature is varied and during exposure to high vapor concentrations. 48 refs., 15 figs., 6 tabs.

The effect of film thickness on in-plane molecular orientation and stress in polyimide films prepared from pyromellitic dianhydride with 4,4′-oxydianline was investigated using a prism coupling technique to measure the refractive index. Film thickness was controlled by varying both solution concentration and spinning conditions. Birefringence, the difference between the in-plane and out-of-plane refractive indices, was used to characterize the in-plane molecular orientation. The observed birefringence is a combination of the birefringence resulting from molecular orientation and the birefringence induced by the residual stress present in the films. The birefringence decreases with increasing film thickness over the range of thicknesses studied (3–20 μm) indicating that the molecular orientation decreases with increasing film thickness. The in-plane coefficient of linear thermal expansion (CTE), controlled by the level of orientation in the film, increases from 18 to 32 × 10−6/°C over the same thickness range. The birefringence of free-standing films was lower than that of adhered films due to the release of residual stress in the film once the film is removed from the substrate. The residual film stress arises primarily from the mismatch in CTEs between the polyimide film and the substrate to which the film is adhered. Thus, since the film anisotropy decreases with increasing thickness, the film stress increases with increasing thickness. Residual stress calculated by integrating the product of the film modulus and the CTE mismatch assuming temperature-dependent properties is comparable to experimentally measured film stress. Ignoring the temperature dependence of the film properties leads to an overestimation of stress. Moisture uptake was used to study the stress dependence of the optical properties. Moisture uptake increases both the in-plane and out-of-plane refractive indices by equal amounts in free-standing films due to an isotropic increase in the polarizability. In adhered films, an increase in moisture uptake leads to a decrease in the birefringence due to a swelling-induced decrease in the residual film stress. © 1994 John Wiley & Sons, Inc.

The effect of surface microstructure on the response of thickness-shear mode resonators in contact with liquids has been examined. Resonators were fabricated with different degrees of random surface roughness by polishing AT-cut quartz crystals with various abrasive particle sizes and then depositing conformal Cr/Au electrodes. The electrical response of liquid-contacted resonators was measured over a range of frequencies near resonance and fit to an equivalent-circuit model. A method is described for determining the complex shear mechanical impedance (the ratio of shear stress to particle velocity at the solid/liquid interface) from the equivalent-circuit elements. This impedance is sensitive to the influence of surface microstructure on the solid/liquid interaction. The surface mechanical impedance was measured while surface roughness, contacting liquid properties, device operating frequency, and liquid contact angle were varied. Results show that, for roughness features much less than the liquid decay length, the surface may be considered hydrodynamically smooth and the responses depend only on the density-viscosity product. As features become comparable to or larger than the decay length, new mechanisms, including liquid trapping and compressional wave generation, arise for energy storage and power dissipation. 53 refs., 14 figs., 3 tabs.

Integrated optics techniques (i.e., guiding light through a thin film) have been used to study the effects of extended cure and moisture exposure on polyimide films as manifested in changes in the TE (in-plane) and TM (out-of-plane) refractive indices and in their difference (birefringence). Mechanical testing of these films has been done using the load-deflection technique. Du Pont polyimide Pyralin 2555 and 2556 (benzophenone tetracarboxylic dianhydride-oxydianiline/metaphenylene diamine), cured repeatedly at 400°C and 375°C respectively, show an increase in refractive index as a function of cure (possibly due to densification), as well as an increase in birefringence (due to increased residual stress). Upon exposure to moisture, the TM and TE refractive indices both increase (absorption of the polar water molecule), but the TE index does not increase as much. Mechanical testing has shown that the residual stress in the polyimide film increases with extended cure and decreases with moisture exposure due to moisture-induced swelling of the film. A model is proposed which relates the optical results to the mechanical measurements. Based on our data, a preliminary stress-optic coefficient is reported.

The signal, power, and communications provisions for the distributed con trol processing, sensing, and actuation of an intelligent structure could benefit from a method of physically embedding some electronic components. The preliminary feasibility of embedding electronic components in load-bearing intelligent composite structures is addressed. A technique for embedding integrated circuits on silicon chips within graphite/ epoxy composite structures is presented which addresses the problems of electrical, mechanical, and chemical isolation. The mechanical isolation of test articles manufac tured by this technique is tested by subjecting them to static and cyclic mechanical loads; chemical isolation is tested by subjecting them to electrical bias in a high temperature, high humidity environment. The likely failure modes under these conditions are iden tified, and suggestions for further improvements in the technique are discussed.

Two polysilicon variable-capacitance rotary side-drive micromotor types, including harmonic and salient-pole, are described. Voltages as low as 26 and 35 V across 1.5- mu m gaps are sufficient for operating the harmonic and salient-pole side-drive micromotors, respectively. Extended operation of the harmonic micromotors to near 100 million wobble cycles is studied at excitation frequencies of 10000 and 25000 r/min for operational durations of 150 and 71 h, respectively. The results of in situ quantitative studies indicate that, with micromotor operation, the rotor inner radius asperities wear out and the bearing clearance increases. This bearing wear is significant and results in changes in the gear ratio of the harmonic micromotors by as much as 22%. Typical gear ratios are near 90 at the start of harmonic micromotor operation and decrease to near 70 as the bearings wear out. For the salient-pole micromotors, wear particles are observed to form in the bearing and at the bushings. These wear particles adhere to the bushing surfaces and the area near the edge of the rotor inner radius. >

The dynamometry technique uses a strobe flash which is triggered from a phase excitation signal after a known time delay. This acts essentially as a video shutter allowing the position of the rotor as a function of the time delay to be recorded and measured. A dynamic model is developed that includes an electrostatic drive term, a velocity-dependent viscous drag term, and a Coulomb friction term that is dependent on the square of the drive voltage and the sign of the velocity. From the position-versus-time data, coefficients for this model are estimated using nonlinear least square error estimation. It is shown that both viscous drag and Coulomb friction terms are required if the model is to closely fit all the experimental data. The motor dynamics are shown to have a weak, if any, dependence on the rotor-bushing apparent area of contact. >

This paper presents a detailed discussion of the critical issues it the design and fabrication of polysilicon, rotary, variable‐capacitance, side‐drive, electric micromotors. Three different side‐drive motor architectures with stator pole number to rotor pole number ratios of 3:1; 3:2, and 2:1 are considered. For each architecture, output torque characteristics of typical microfabricated motors are simulated using two‐dimensional finite‐element solutions in the plane of the substrate. The 3:2 design is shown to provide superior torque coverage with higher minimum torque values as compared to the other two designs. An examination of the contribution of the axial fringing fields shows that, for typical micromotors, the rotor–stator capacitance is more directly a function of the rotor–stator thickness and not of the vertical rotor–stator pole‐face overlap. Furthermore, since the rotor–stator capacitance is not very sensitive to a vertical offset between the rotor and the stator, electric forces tending to vertically align the rotor to the stator are significantly smaller than would be predicted from a simple parallel‐plate capacitance calculation. A standard and a localized oxidation of silicon (LOCOS)‐based side‐drive micromotor fabrication process are described. The standard process is used as a case study to provide a detailed discussion of practical issues that need to be considered in the development of a polysilicon surface‐micromachined motor fabrication process. Specific motor design examples are described and a brief history of our experimental findings is presented. Typical 3:2 micromotors have been operated with bipolar excitations as low as 37 V across 1.5 μm gaps and at speeds as high as 15 000 rpm.

Heavily boron doped membranes are shown to be under tensile intrinsic stress with a negative intrinsic bending moment. However, the use of an oxide etc

This paper discusses the design, microfabrication, operating principles and experimental testing of three types of rotary variable-capacitance micromotors. The advantages and disadvantages of these motors are discussed. The three motor types are top-drive, side-drive and harmonic side-drive. In this work, the micromotors are surface micromachined using heavily-phosphorus-doped polysilicon for the structural material, deposited oxide for the sacrificial layers and LPCVD nitride for electrical isolation. Frictional forces associated with electric pull-down forces on the rotor are dominant in the side-drive and harmonic side-drive motors fabricated and tested to date. Air drive and electric excitation have been used in studying these effects. Side-drive micromotors have been successfully operated by a three-phase electrical signal with the rotors air-levitated. With air levitation, successful operation is achieved at bipolar excitations greater than 80 V across 4 μm air-gap motors having eight rotor and twelve stator poles, with only half of the stator poles excited. Motor operation is sustained indefinitely.

The objective of this work was to develop methods which would allow the electromechanical analysis of a Microelectromechanical System (MEMS) structure with the level of complexity of a practical, high-volume manufacturable sensor while avoiding computationally impractical models. Two methods were developed. One was a simple analysis method in which the ideal structure was assumed. This allowed prediction of the stability and the effects of structure misalignment on a surface-micromachined ac,:elerometer. However, the simple method is limited bccause the actual structure has fabrication induced non-idealities, such as warpage, which can cause the simple method to be significantly in error. The second method discarded the ideal structure assumption and analyzed the non-ideal structure via a self-consistent analysis. This method is based on the calculation of an intermediate look-up table from which the electrostatic forces are obtained directly from the position of the moving mass, greatly reducing computation time and memory requirements in comparison to a standard self-consistent electromechanical analysis scheme. Using this lumped-model self-consistent scheme, we analyzed an Analog Devices, Inc. ADXL50 accelerometer including fabrication non-idealities (warpage, overetching, residual stress, etc.). For this structure the lumped-model self-consistent analysis method reduced the required number of electrostatic analysis discretization panels by a factor of about 100. Computation times were typically 5-7 hours instead of a predicted time of more than a month for a standard self-consistent electromechanical analysis scheme. Further, memory requirements for the standard method would have significant,ly exceeded practical limitations. The electromechanical resonant frequency was measured for several ADXL50 accelerometers and compared to t,he simulat,ion results showing good agreement.

We have demonstrated that wafer-level probing of electrostatic pull-in test structures provides a means to monitor MEMS process uniformity and integrity. Test structures, which have proved to be useful in determining MEMS material properties, are used here to identify and quantify a non-uniform plasma over-etch used in the final release of silicon wafer-bonded microstructures. MEMCAD simulations confirm that the changes in test structure geometry do indeed account for the behavior seen experimentally.

While there have been diverse and astonishing advances in the development of technologies and device concepts for microsensors and microactuators, it is still largely true that the creation of a new device is a research and development project instead of a design project. This paper examines the future of microsensors and microactuators from the perspective of the designer — someone who seeks to take an idea and, with the aid of suitable modeling and simulation tools, create a design for building the device in a specified process which can be expected to work successfully after the first fabrication run.

There has been no shortage of bright ideas in the area of microsensors, microactuators, and microelectromechanical devices of all sorts. However, the track record on converting those ideas into commercially successful products has seemed uneven to some, both inside and outside the field. It has taken as much as 15 to 20 years (or more) between early research prototypes and full commercialization for such devices as silicon pressure sensors, accelerometers, ion sensors, and optical displays, somewhat less for some of the passive components such as microfluidic cells for biological application. This paper looks back to the gathering at the Materials Research Society in Boston in 1981 out of which the sequence of Transducers conferences was born, illustrates how far the field has progressed since, and then examines some of the real hurdles that must be overcome during the process of creating products from ideas.

Based on his many years of experience, a JMEMS editor provides guidelines for authors that will, if followed, greatly reduce the risk of a devastatingly negative result from the review process. The premise is that there are certain things that rightfully anger reviewers, and, once angered, the reviewers become both negative and aggressive in their judgments--hence, the imagery of "the reviewer's axe" and how to avoid it.

Microelectromechanical Systems (MEMS) and optics are a natural match. There are several reasons: MEMS devices have dimensions and achievable actuation distances comparable to the wavelength of light; smooth-surfaced dielectrics, semiconductors, and metals can be used in various combinations; and, photons don't weigh anything, so relatively feeble MEMS actuators can easily manipulate them. Many optical MEMS devices are based on mirror arrays that can be tilted using electrostatic actuation. This paper, however, focuses on programmable diffraction gratings and their uses for projection displays, spectroscopy, and wavelength management in modern optical telecommunication systems.

We describe the development of a MEMS-based correlation radiometer for remote detection of chemical species. The radiometer utilizes a new type of MEMS programmable diffraction grating called the Polychromator. The Polychromator contains an array of 1024 electrostatically actuated reflective beams that are 10 microns wide by 1 cm long, and have a vertical travel of approximately 2 - 4 microns. The Polychromator grating is used to replace the reference cell of conventional correlation radiometry. Appropriate programming of the deflection profile of the grating array enables the production of any spectral transfer function desired for the correlation measurement. Advantages of this approach to correlation radiometry include the ability to detect multiple chemical species with a compact instrument, the ability to optimize the reference spectra to eliminate chemical interferences, and the ability to produce reference spectra for hazardous and transient species.

A simple quantitative model for the metal-PI-metal system was used to calculate space-charge modified conduction transients in PI (polyimide). Experimental data from PI samples containing controlled ion content are compared with numerically computed current-time transients. The calculated transients model the gross trends observed in experimental data. The effect of mobile ions is to change the shape of the current transient, but the steady current is not strongly dependent on ionic concentration. It is concluded that a detailed analysis of the formation of space-charge during electrical measurements is critical to the understanding of transient phenomena in insulating polymers. >

A thermally isolated microstructure for use in metal-oxide gas sensing applications was fabricated and tested. Using the techniques of bulk micromachining, a thin silicon membrane 5 mu m thick was fabricated and then used as a structural support during subsequent device processing. The mechanical stability of the thin silicon membrane was found to be dependent on the compressive surface-oxide thickness which induced membrane buckling. A study of the buckling criteria was examined in detail by performing etch-back experiments on a series of sequentially sized membranes and observing the transition for buckling. A linear relationship between oxide thickness and membrane edge length squared was found. The device is fabricated over the membrane on the wafer surface and consists of a sandwich of LPCVD Si/sub 3/N/sub 4/, LPCVD poly-Si and LPCVD Si/sub 3/N/sub 4/. After device fabrication, the support membranes is etched away leaving the device completely isolated from the substrate. The measured values of power consumption and thermal time constant are compared with a simple model. >

Calibration of the suspended square membrane method using both finite-element methods (FEM) and comparison with conventional tensile tests is discussed. The use of suspended circular membranes to measure the elastic limit of thin films is reported. The techniques can be adapted to other thin films from which microfabricated specimens can be made. The Instron test results provided useful information about the material behavior, including Young's modulus, whereas the membranes were used to determine quantitative values for residual stress and elastic modulus. The axisymmetric state of circular membranes under pressure were utilized effectively in determining the elastic limit of thin polymer films. >

A twin-interferometer fiber-optic readout scheme has been developed to monitor the deflection of pressure transducer diaphragms. This technique has a potential advantage at high temperatures, since the circuitry is kept at room temperature and is coupled to the sensor head via optical fibers. The interference scheme used differs from conventional interferometry in that: light is carried forward to the diaphragm and backwards to the photodetectors using a single fiber; and the cleaved fiber end-face itself acts as the reference plane for the interference cavity. A single interferometer cannot uniquely determine the direction of motion, but two such interferometers in parallel, i.e. the twin-interferometer, do provide the necessary information to measure both the magnitude and direction of deflection. Prototype sensor assemblies and detection circuitry have been developed and tested in an industrial setting. Limiting factors on sensor performance have been identified. This technique should also be applicable to other mechanical sensors in which deflections must be monitored. >

The fabrication and initial testing of silicon micromachined flow chambers for applications in flow cytometry are reported. The flow chambers consist of a hexagonal flow duct with inlet and outlet ports, thin-film windows on the top and bottom of the duct, and integrated optical waveguides positioned to intercept the center of the duct within the visible area defined by the windows. An opening for a hypodermic needle allows injection of a suspension of microscopic particles into a liquid stream flowing through the duct. Each component of the device was tested individually, and good agreement between the experimental data and theoretical models was observed. Laminar flow was observed in several prototypes up to mean flow speeds of 3 m/s. No leaks were detected for inlet pressures as high as 30 psi. >

The development of a first implementation of the MEMCAD system (version 1.0) is reported. The system is composed of three commercial mechanical CAD software packages integrated with specialized structure generation and electrostatic analysis programs. The authors describe the system and demonstrate its capabilities using a comb drive example constructed directly from a CIH description of its mask set. The analysis of the comb drive, all the way from generating a full 3-D model from mask descriptions to calculating comb levitation forces, takes just a few hours. >

This paper discusses the modeling of electromechanical hysteresis in devices which exhibit contact between components. We make use of a recently developed tool, CoSolve-EM, in order to solve quasistatic 3D contact electro-mechanics for a clamped-clamped beam, calculating full displacement, capacitance and contact force vs. voltage. We then extend the simulations to two design variations of the beam which permit engineering of its hysteresis characteristics.

Design of MEMS devices which apply electrostatic forces to deformable structures is complicated by the fact that as the structure deforms, the charges redistribute, thereby modifying the mechanical loads. This paper reports three different levels of model used to simulate such structures: a very simple lumped parallel-plate-capacitor-plus-spring model, a one-dimensional numerical model based on beam and/or plate theory with loads derived from an incrementally parallel-plate capacitor, and a fully self-consistent three-dimensional numerical simulation combining finite-element structural modeling with multipole-accelerated boundary element capacitance analysis. The relative merits of each model are described, and several specific examples are examined. The lumped model has the advantage of simplicity plus a full analytic description, which permits assessment of stability of solutions. The one-dimensional numerical model, in the specific cases examined, agrees with the full 3-D model, and is computationally far less costly However, the simple structures examined here have nearly parallel conductors which remain in the small-deflection regime up to the pull-in voltage. For non-parallel conductors, and for structures which involve large deflections, the full 3-D model will be required. Furthermore, the full 3-D model is extremely valuable in identifying the limitations of the beam-theory simulation, some of which could be critical to a design.

A Micro-ElectroMechanical Computer-Aided Design (MEMCAD) system is being developed to make it possible for microsensor designers to perform realistic simulations easily and quickly. Carefully selected commercial software packages have been linked with specialized databases and numerical programs to allow a designer to enter a three-dimensional microsensor geometry and quickly perform both mechanical and electrical analysis. The authors briefly describe the system and demonstrate its effectiveness by accurately calculating the capacitance versus pressure (or force) curve for a square diaphragm deformed by a differential pressure and for a rectangular beam deflected by a centrally applied force. The MEMCAD system has successfully implemented the following: querying a material property database for material property insertion, combining a 3-D solid model with displacement information from the finite element method, and interfacing the 3-D solid model format with a capacitance extraction program. >

A CAD architecture for microelectromechanical systems is presented in which conventional mask layout and process simulation tools are linked to three-dimensional mechanical CAD and finite-element tools for analysis and simulation. The architecture is exercised by an elementary example on the stress-induced curvature of an oxidized silicon wafer. An architecture for an object-oriented material property simulator in which material properties and their process dependence are stored and are accessed based on the specific process conditions is also presented. >

An efficient 3-D numerical tool for modeling and simulating field-emission devices (FED) is presented. This tool uses an accelerated boundary-element-method (BEM) electrostatics solver and an adaptive explicit integration method. The typical CPU time for a complete electrostatics and trajectory simulation is less than 1 hour, versus a few hours/days for 3-D finite-element-methods (FEM). The simulated results of a single-gate field emitter array (FEA) are in excellent agreement with experimental results. Simulation examples of proximity focusing FEDs and integrated-focus-electrode (IFE) focusing FEDs are also presented. The results provide good guidelines for device design and operation.

This paper analyzes the dynamics and associated sensitivity limitations of a differential capacitive sensing scheme to determine the position of an elastically supported plate. Short pulses are applied differentially to a sense capacitor and reference capacitor. The voltage that appears on their shared node during the sense pulse is proportional to the difference between the two capacitances. The pulses impart kinetic energy to the supported plate, and after the pulses are removed, the mechanical system undergoes oscillatory motion. This paper analyzes the electro-mechanical dynamics of both the sensing procedure and a proposed resistive damping method that permits effective damping even in vacuum.

When wet etches are used to release a large microstructural element, it is common practice to distribute small holes in the microstructure to promote under-etching and release, and for reduction of squeezed-film damping. In this paper, we demonstrate that while the mechanical properties are strongly affected by the presence of etch holes, because of fringing-field effects at the edges of the etched holes, the electrostatic-force behaviour of structural elements with an array of small etched holes is nearly that of an unetched element. This leads to an "effective medium" approximation for the mechanical material that can then be used with standard electrostatic actuation models to give good predictions of electromechanical behaviour. Comparison with experimental device behaviour shows the validity of this approach.

In this paper, we present a methodology for extracting macromodel parameters of compressible isothermal squeezed-film damping (CISQFD) for flexible structures of MEMS under small amplitude oscillation. The theoretical derivation, which is based on structural modal analysis and CISQFD numerical simulation, is presented. The spring and damping components of CISQFD of any oscillation mode can be extracted by this methodology, and thus the generic parameters of CISQFD can be obtained for any flexible structure with given oscillation modes. We successfully formulated an accurate and concise second order dynamics equation for a flexible MEMS devices by using the CISQFD parameters and the modal spring constant and mass. Simulation results of resonance shift and quality factor are consistent with experimental results.

MIT is developing a MEMS-based gas turbine generator. Based on high speed rotating machinery, this 1 cm diameter by 3 mm thick SiC heat engine is designed to produce 10-20 W of electric power while consuming 10 grams/hr of H/sub 2/. Later versions may produce up to 100 W using hydrocarbon fuels. The combustor is now operating and an 80 W micro-turbine has been fabricated and is being tested. This engine can be considered the first of a new class of MEMS device, power MEMS, which are heat engines operating at power densities similar to those of the best large scale devices made today.

In this paper experiments on the quasistatic and dynamic behaviour of the electrostatic polysilicon microrelay fabricated at IMT are presented together with new nonlinear dynamical models. The models simulate the pull-in voltage, the resonance frequency, the quality factor, the switching time and the electrostatic spring softening of the microrelay. Simulation of the pull-in voltage has been done with MIT's MEMCAD system, the resonance frequency has been simulated with Abaqus/sup TM/, while macro-models developed at MIT have been used to simulate the dynamics of the nonlinear actuator in the presence of squeeze-film damping.

In this paper, are describe how a few simulations of fully meshed dynamical problems can be used to construct efficient low-order models for system-level design of microstructures. We report on the use of this method to capture the measured behaviour of a pressure sensor based on the pull-in time of a beam. Results show that the reduced order model decreases simulation time by at least a factor of 37 while achieving good agreement with experimental data.

The squeezed-film damping component of the pull-in time of an electrostatically-actuated micromechanical fixed-fixed beam is shown to be a sensitive, and nearly linear function of ambient air pressure in the measured range of 0.1 mbar to 1013 mbar (1 atm or 760 Torr). Pull-in time simulations, based on a one-dimensional macromodel using a damping constant proportional to pressure, are in good agreement with measured data. The data and simulations show that pull-in type devices will make excellent microelectromechanical systems (MEMS) sensors for broad-range absolute pressure measurements and for in situ leak monitoring of hermetically scaled packages containing other sensors or IC's. The pull-in sensors are compatible with any MEMS fabrication processes that allow out-of-plane electrostatic actuation, including surface micromachining and silicon wafer-bonding, and they do not require a cavity sealed at vacuum or at a reference air pressure.

Summary form only given. Spatial holography stores the shape of an object by recording the phase profile of a monochromatic optical beam. Similarly, the spectral content of an optical beam can be recreated from a stored phase profile of a polychromatic optical beam. Such phase profiles have been created by etching silicon and also with a MEMS-based programmable, diffraction grating. This talk will describe how phase profiles are create to reproduce specific spectral profiles, the development of the programmable diffraction grating, and several potential applications of such a technology.

We present a CAD tool for automatically generating reduced-order models of mechanically dynamic, capacitive microelectromechanical devices directly from a meshed representation of the device. Our work is based on the CHURN process of Gabbay et al. Our new contributions are the extension of this methodology to devices with multiple electrodes, the automated selection of relevant modes for such problems and a set of heuristics for automating the model generation algorithm. We demonstrate use of the tool on a fabricated microelectromechanical filter.