Showing papers in "Proceedings of SPIE in 1997"
TL;DR: This paper proposes a new scheme based on fractal coding and decoding that exploits the spatial redundancy within the image by establishing a relationship between its different parts and describes a way to use this relationship as a means of embedding a watermark.
Abstract: With the increase in the number of digital networks and recording devices, digital images appear to be amaterial, especially still images, whose ownership is widely threatened due to the availability of simple,rapid and perfect duplication and distribution means. It is in this context that several European projects aredevoted to finding a technical solution which, as it applies to still images, introduces a code or Watermarkinto the image data itself. This Watermark should not only allow one to determine the owner of the image,but also respect its quality and be difficult to remove. An additional requirement is that the code should beretrievable by the only mean of the protected information. In this paper, we propose a new scheme basedon fractal coding and decoding. In general terms, a fractal coder exploits the spatial redundancy within theimage by establishing a relationship between its different parts. We describe a way to use this relationshipas a means of embedding a Watermark. Tests have been performed in order to measure the robustness ofthe technique against JPEG conversion and low pass filtering. In both cases, very promising results havebeen obtained.Keywords: digital signature, watermarking, image, copyright protection, security, fractal compression, IFS(Iterated Function Systems), FVT (Fractal Vector
141 citations
TL;DR: In this paper, a method to pattern self assembled monolayer films of n-octadecyltrichlorosilane on silicon and glass substrates using a simple lift-off procedure was developed.
Abstract: We have developed a method to pattern self assembled monolayer films of n-octadecyltrichlorosilane on silicon and glass substrates using a simple lift-off procedure. By defining hydrophobic regions at definite locations in microchannels and using an external pressure source, we can split off precise nanoliter volume liquid drops and control the motion of those drops through the microchannels. We have also constructed an on-chip pressure source for drop splitting and motion by heating air trapped in a micromachined chamber. Both techniques can produce and move drops on the order of 50 nl.
84 citations
TL;DR: In this article, the authors report on the design, construction, and initial testing of surface micromachined devices for measuring friction and wear on both horizontal and vertical etched polysilicon surfaces.
Abstract: We report on the design, construction, and initial testing of surface micromachined devices for measuring friction and wear. The devices measure friction coefficients on both horizontal deposited polysilicon surfaces and vertical etched polysilicon surfaces. The contact geometry of the rubbing surfaces is well-defined, and a method is presented for the determination of the normal and frictional forces. Initial observations on test devices which have been dried with supercritical CO{sub 2} and devices coated with octadecyltrichlorosilane suggest that the coatings increase the lifetime of the devices and the repeatability of the results.
70 citations
TL;DR: In this paper, the authors describe how nonlinear force flexures can be used to increase the stable deflection distance of an electrostatically operated micromirror, and present a theoretical simulation of traditional and higher order flexures.
Abstract: This paper describes how nonlinear force flexures can be used to increase the stable deflection distance of an electrostatically operated micromirror. Traditional micromirrors have flexures that provide linear force as a function of deflection. Electrostatic attraction is a nonlinear force, so after a traditional micromirror has deflected one-third of the initial separation distance between the top and bottom electrode, the mirror's position becomes unstable, and the mirror quickly jumps down to the bottom electrode. This phenomenon is called 'snap-through,' and it has been well-documented. A nonlinear second order flexure has a restorative force that is proportional to the square of the deflection distance. A second order flexure does not exhibit snap-through until the micromirror is deflected one-half the initial separation between the top and bottom electrode. Higher order flexures are capable of traveling a larger distance before snap-through. This paper presents a theoretical simulation of traditional and higher order flexures. Specific nonlinear flexure designs have been constructed and demonstrated.
59 citations
TL;DR: In this article, the authors proposed a new polysilicon actuator design that eliminates the parasitic electrical resistance of the cold arm through the use of an additional hot arm, which results in an improvement in electrical efficiency by providing an active return current pass.
Abstract: This paper presents a new polysilicon actuator design. In a typical thermally-driven actuator, the hot arm is thinner than the cold arm, so the electrical resistance of the hot arm is higher. When electric current passes through the device (both the hot and cold arms), the hot arm is heated to a higher temperature than the cold arm. This temperature increase causes the hot arm to expand in length, thus forcing the tip of the device to rotate about a flexure. The new thermal actuator design eliminates the parasitic electrical resistance of the cold arm through the use of an additional hot arm. The second hot arm results in an improvement in electrical efficiency by providing an active return current pass. Also, the rotating cold arm can have a thinner flexure than the flexure in a traditional device because it does not have to pass an electric current. The thinner flexure results in an improvement in mechanical efficiency. This paper compares single and double hot arm thermallydriven actuator designs, and demonstrates various devices constructed with the new thermal actuator design. Deflection and force measurements of both actuators as a function of applied electrical current are presented. Keywords: MEMS, Polysilicon, Actuator, Motor, Mirror.
57 citations
TL;DR: In this paper, the authors describe the synchronized mask scanning and mask dragging techniques and illustrate their application by presenting details of novel micromachined structures and devices so produced, including rapid prototyping of bioprocessor chips, fabrication of mechanical anti-reflection structures in CsI infra-red optical material, patterning films as frequency selective reflecting structures, laser-LIGA and high aspect ratio machining using lamination techniques to produce an optical methane detector.
Abstract: New techniques for 3D micromachining by direct laser ablation of materials using excimer lasers have been developed. Basic to all of these techniques is the use of image projection in which the laser is used to illuminate an appropriate pattern on a chrome-on-quartz mask. The mask is then imaged by a high- resolution lens onto the sample. Non-repeating patterns with areas of up to 150 multiplied by 150 mm can be machined with sub-micron resolution and total accuracies of the order of a few microns by using synchronized scanning of the mask and workpiece. A combination of synchronized mask scanning and mask dragging techniques (in which the mask is held stationary and the workpiece moved during laser firing) enables patterns of up to 400 multiplied by 400 mm to be produced; the limiting feature being the travel and accuracy of the recision air- bearing stages used to support the workpiece. This talk describes the synchronized mask scanning and mask dragging techniques and illustrates their application by presenting details of novel micromachined structures and devices so produced. These include rapid prototyping of bioprocessor chips, fabrication of mechanical anti-reflection structures in CsI infra-red optical material, patterning films as frequency selective reflecting structures, laser-LIGA and high aspect ratio machining using lamination techniques to produce an optical methane detector.
55 citations
TL;DR: The first-ever reliability stress test on surface micromachined microengines developed at Sandia National Laboratories (SNL) has been completed and the reliability data are presented and interpreted using standard reliability methods.
Abstract: The first-ever reliability stress test on surface micromachined microengines developed at Sandia National Laboratories (SNL) has been completed. We stressed 41 microengines at 36,000 RPM and inspected the functionality at 60 RPM. We have observed an infant mortality region, a region of low failure rate (useful life), and no signs of wearout in the data. The reliability data are presented and interpreted using standard reliability methods. Failure analysis results on the stressed microengines are presented. In our effort to study the reliability of MEMS, we need to observe the failures of large numbers of parts to determine the failure modes. To facilitate testing of large numbers of micromachines. The Sandia High Volume Measurement of Micromachine Reliability (SHiMMeR) system has computer controlled positioning and the capability to inspect moving parts. The development of this parallel testing system is discussed in detail.
52 citations
TL;DR: In this article, the authors present a micro-opto-electro-mechanical (MOEM) application employing vertical thermal actuators, where the actuators are comprised of a polysilicon cantilever bar mechanically coupled to two expansion arms.
Abstract: This paper presents novel micro-opto-electro-mechanical (MOEM) applications employing vertical thermal actuators. The high force and large deflection of backbent vertical thermal actuators are useful in many applications, particularly when a single large deflection is required for device setup. For example, backbending two actuators driven in parallel flips a 250 micrometer square mirror to 45 degrees off the substrate. The actuators can then be driven to permit scanning over 45 degrees. In another example, 3 backbent actuators are used to position an electrostatically actuated optical beam steering mirror 10 micrometer off the substrate thereby increasing the maximum steering angle by a factor of 5. Critical to applications like these is predictable and repeatable operation of the actuators. The actuators are comprised of a polysilicon cantilever bar mechanically coupled to two expansion arms. If sufficient current is driven through the expansion arms they deform, bowing upward. Upon removal of the drive current the expansion arms shrink, backbending the actuator by pulling the tip of the actuator upward. Test actuators of three different sizes were carefully backbent. After backbending, the deflection of each actuator was measured on an interferometric microscope with plus or minus 5 nm precision. Although nonlinear, the relationship of backbending deflection to drive power is well behaved, and repeatable.
44 citations
TL;DR: In this paper, Sandia's micro-engine was used as the actuation device in gear systems rotating on hubs to prevent failure due to sticking of structures that are in sliding contact.
Abstract: Gear systems rotating on hubs have been operated to failure using Sandia`s microengine as the actuation device. Conventional failure modes such as fatigue induced fracture did not occur, indicating that the devices are mechanically extremely robust. The generic route to failure observed for all rotating devices involves sticking of structures that are in sliding contact. This sticking evidently results from microscopic changes in the sliding surfaces during operation. The rate at which these changes occur is accelerated by excessive applied forces, which originate from non-optimized designs or inappropriate drive voltages. Precursors to failure are observed, enabling further understanding of the microscopic changes that occur in the sliding surfaces that ultimately lead to failure.
40 citations
TL;DR: This work describes a machine vision based traffic sensor under development that uses sophisticated color signatures as a key component for point-to-point traffic variables like travel time.
Abstract: In order to support intelligent traffic management systems, future traffic sensors will need to provide more traffic variables, and more accurate data than provided by the commonly used sensors today. In particular, future systems will need to recognize vehicles from sensor to sensor in order to measure point-to-point traffic variables like travel time. One characteristic that may be used to match vehicles between sensors is color. This work describes a machine vision based traffic sensor under development that uses sophisticated color signatures as a key component.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
38 citations
TL;DR: In this article, a backlight for LCDs that creates autostereoscopic 3D with no sacrifice in quality to conventional 2D images is presented, which is comparable in size and cost to standard 2D backlights and can be manufactured using similar processes.
Abstract: DTI has demonstrated a backlight for LCDs that creates autostereoscopic 3D with no sacrifice in quality to conventional 2D images. The new backlight is comparable in size and cost to standard 2D backlights and can be manufactured using similar processes. Prototypes have been used in amusement games, LCD desk top monitors, and PC Notebooks. An acrylic light guide accepts light from a miniature fluorescent lamp. Linear structures on one side of the guide reflect light traveling through it toward the LCD. A lenticular lens images the light from the structures into a much larger number of thin light lines within the LCD glass. These lines are spaced in a precise relationship with the pixels of the LCD so that an observer sitting in front of the display sees all the light lines through the odd columns of pixels with the left eye and through the even columns of pixels with the right eye. An electronic shutter is placed between the light guide and the lenticular lens. In the off state the shutter will diffuse the light from the light lines for 2D mode viewing. In the clear state (power on), the light lines are visible for 3D mode viewing.
TL;DR: In this paper, a micromanipulator is used to measure force and displacement with high resolution, and a tensile test of the beam is performed by an arm actuated by a piezoelectric element and equipped with a probe.
Abstract: The mechanical properties of thin film microstructures depend on size and shape and on the film manufacturing process. Hence, the test structures that are used to measure mechanical properties should have dimensions of the same order of magnitude as an application structure. The microstructures are easily monitored in a scanning electron microscope (SEM), but to be handled and tested in situ a micromanipulator was developed. The parts of the micromanipulator essential to the tests are two independently moveable tables driven by electric motors. The test structures and a testing unit are mounted on the tables. A testing unit was designed to measure force and displacement with high resolution. The testing unit consists of an arm actuated by a piezoelectric element and equipped with a probe. An optical encoder measures the movement of the arm, while strain gauges measure the force in the arm. Test structures consist typically of a released beam fixed at one end with a ring at the other. The micromanipulator is used to position the probe of the testing unit in the ring. The testing unit then executed a tensile test of the beam. Test structures of polysilicon films produced under various process conditions were used to verify the possibility of measuring Young's modulus with an accuracy of +/- 5 percent, as well as fracture strength.Young's modulus is calculated using the difference in elongation for different beam lengths. The fracture strength of the beams was evaluated with Weibull statistics.
TL;DR: In this paper, the authors used the levitation effect of comb fingers to design a vertical-to-the-substrate actuation for phase shifting interferometric applications, where the capacitance of the fingers was used to control the vertical movement of the microactuator.
Abstract: The electrostatic comb finger drive has become an integral design for microsensor and microactuator applications. This paper reports on utilizing the levitation effect of comb fingers to design vertical-to-the-substrate actuation for interferometric applications. For typical polysilicon comb drives with 2 {micro}m gaps between the stationary and moving fingers, as well as between the microstructures and the substrate, the equilibrium position is nominally 1-2 {micro}m above the stationary comb fingers. This distance is ideal for many phase shifting interferometric applications. Theoretical calculations of the vertical actuation characteristics are compared with the experimental results, and a general design guideline is derived from these results. The suspension flexure stiffnesses, gravity forces, squeeze film damping, and comb finger thicknesses are parameters investigated which affect the displacement curve of the vertical microactuator. By designing a parallel plate capacitor between the suspended mass and the substrate, in situ position sensing can be used to control the vertical movement, providing a total feedback-controlled system. Fundamentals of various capacitive position sensing techniques are discussed. Experimental verification is carried out by a Zygo distance measurement interferometer.
TL;DR: A fast algorithm for the generation of a symmetry histogram is presented, whose (sufficiently strong) peaks indicate the likely presence and approximate location of a vehicle.
Abstract: Video systems can locate, identify and track vehicles. A video-based vehicle detection and location method is presented, which exploits the symmetry of vehicles seen from behind. The method can account for a range of symmetry types. These include (1) simple pixel presence in a binary edge image, (2) gray level of the edge pixel, (3) color value of the edge pixel, and (4) connectedness structure of the (binary) pixels around an edge pixel. A fast algorithm for the generation of a symmetry histogram is presented, whose (sufficiently strong) peaks indicate the likely presence and approximate location of a vehicle. The speed of the algorithm results from its data driven nature. Typical results for this algorithm in dense urban traffic are presented, using symmetry type (1). The generalization of the algorithm to skew symmetric images is shown. A potential application of the algorithm to automated roadways and fatigue detection is sketched out. Robustifying extensions in the spirit of (2), (3) and (4) are proposed.
TL;DR: In this article, a new methodology to fabricate the above discussed arbitrarily shaped structures using a one-level gray-tone lithography process is presented. But this technique is common to standard IC manufacturing processes, supplemented by some processes like spincoating and developing of a thick resist layer, electroplating of thick metal layers and dry etching.
Abstract: To fabricate arbitrarily shaped microrelief surfaces you should be able to design and control beside the X- and Y- direction also the Z-direction. With common micromachining technologies this could not be obtained. The surface micro machining technology, with sacrificial layer etching as a key process, is a planar technology, which offers no degree of freedom to design the surface in Z-direction. The bulk micro machining technology, with anisotropic KOH etching of silicon as a key process, offers only restricted possibilities for 3D design. To overcome this limitation binary optical elements have been fabricated using multi-mask processes or multidose e-beam or laser writing. For refractive optical lenses resist melting is a good compromise. This paper reports on a new methodology to fabricate the above discussed arbitrarily shaped structures using a one step lithography process. This technique is called one-level gray-tone lithography, which is common to standard IC manufacturing processes, supplemented by some processes like spincoating and developing of thick resist layer, electroplating of thick metal layers and dry etching. This group of processes has been collected into a new technology category with free design capabilities in Z- direction up to 20 micrometer: relief micro machining. Particular emphasis is put on the design of the halftone transmission masks. The algorithms to transfer an initial height profile into a design representation in the common data format GDSII are discussed. The great data amount of a reticle layout is reduced significantly by a first order data compaction. The specific parameters for the mask making and the resist process are determined. Several components like shaped gratings or lenses are shown in resist up to 15 micrometers thick. In the field of transferring the pattern into a substrate material like silicon or glass, a dry etching process is evaluated.
TL;DR: The mechanical design aspects of these latest micromachines will be discussed with particular emphasis on a number of design modifications that improve the power, reliability, and smoothness of operation of the microengine.
Abstract: Quad-level polysilicon surface micromachining technology, comprising three mechanical levels plus an electrical interconnect layer, is giving rise to a new generation of micro-electromechanical devices and assemblies. Enhanced components can not be produced through greater flexibility in fabrication and design. New levels of design complexity that include multi-level gears, single-attempt locks, and optical elements have recently been realized. Extensive utilization of the fourth layer of polysilicon differentiates these latter generation devices from their predecessors. This level of poly enables the fabrication of pin joints, linkage arms, hinges on moveable plates, and multi-level gear assemblies. The mechanical design aspects of these latest micromachines will be discussed with particular emphasis on a number of design aspects of these latest micromachines will be discussed with particular emphasis on a number of design modifications that improve the power, reliability, and smoothness of operation of the microengine. The microengine is the primary actuation mechanism that is being used to drive mirrors out of plane and rotate 1600-{mu}m diameter gears. Also discussed is the authors most advanced micromechanical system to date, a complex proof-of-concept batch-fabricated assembly that, upon transmitting the proper electrical code to a mechanical lock, permits the operation of a micro-optical shutter.
TL;DR: A general description of the overall ROBART III system is presented, with focus on sensor-assisted reflexive teleoperation of both navigation and weapon firing, and various issues related to non-lethal response capabilities.
Abstract: ROBART III is an advanced demonstration platform for non- lethal security response measures, incorporating reflexive teleoperated control concepts developed on the earlier ROBART II system. The addition of threat-response capability to the detection and assessment features developed on previous systems has been motivated by increased military interest in Law Enforcement and Operations Other Than War. Like the MDARS robotic security system being developed at NCCOSC RDTE DIV, ROBART III will be capable of autonomously navigating in semi-structured environments such as office buildings and warehouses. Reflexive teleoperation mode employs the vehicle's extensive onboard sensor suite to prevent collisions with obstacles when the human operator assumes control and remotely drives the vehicle to investigate a situation of interest. The non-lethal-response weapon incorporated in the ROBART III system is a pneumatically-powered dart gun capable of firing a variety of 3/16-inch-diameter projectiles, including tranquilizer darts. A Gatling-gun style rotating barrel arrangement allows size shots with minimal mechanical complexity. All six darts can be fired individually or in rapid succession, and a visible-red laser sight is provided to facilitate manual operation under joystick control using video relayed to the operator from the robot's head-mounted camera. This paper presents a general description of the overall ROBART III system, with focus on sensor-assisted reflexive teleoperation of both navigation and weapon firing, and various issues related to non-lethal response capabilities.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: In this paper, the authors describe the design, the function and the application of mechanical grippers for automated micro assembly, which can be equipped with sensors for the detection of gripping force and have been designed especially for use in a large-chamber scanning electron microscope (LC-SEM).
Abstract: The assembly of hybrid micro systems is usually done by hand with the help of tweezers and optical microscopes. It is obvious, however, that only the automation will lead to an efficient and precise assembly process. This paper describes the design, the function and the application of mechanical grippers for automated micro assembly. These grippers are powered by piezo systems and are able to move their arms in sub-micrometer steps in order to grip micro parts very precisely. They can be equipped with sensors for the detection of gripping force and have been designed especially for use in a large-chamber scanning electron microscope (LC-SEM). Process observation is a main problem in all aspects of micro technology. The LC-SEM allows on-line process observation with a very high depth of focus and a large lateral resolution. It has a 2 m3 vacuum chamber in which complete assembly units can be installed. Furthermore the electron gun is freely movable, so that a sample can be observed from all directions. An additional advantage of this microscope is the clean production environment (vacuum).© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: The Micrion MicroMill as discussed by the authors is a focused ion beam (FIB) system for automated MEMS processing that has been successfully used in production and prototype milling of over three million thin film heads (TFH) used in hard disk drives.
Abstract: We have developed a focused ion beam (FIB) system for automated MEMS processing. This product, the Micrion MicroMill, has been successfully used in production and prototype milling of over three million thin film heads (TFH) used in hard disk drives. The FIB column consists of a liquid gallium (Ga+) ion source, running at 50 kV, producing beam currents up to 50 nA. The milling rates achieved in the TFH application have been 0.5 - 4 micrometer3/sec with spot sizes ranging from 150 - 800 nm. This tool is designed to easily integrate into current FAB facilities and supports a wide range of navigational requirements. Different milling scenarios can be easily created or modified using the integrate CAD-like design tools, allowing for quick production line design modifications or rapid prototyping of new designs. The milling strategy can 'adapt' to dimensional changes caused by upstream process variations. On a real-time basis, the FIB system's pattern recognition/inspection software measures the individual part and precisely places the desired milling pattern. The flexible vector scan beam control can position the FIB, within sub-tenth micron dimensional control, to generate an endless variety of geometric milling patterns. This presentation will discuss the work currently done on inductive and magnetoresistive TFH devices as well as other potential MEMS processing applications.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: In this paper, the etch rate and the morphology of the etched surface as a function of etch parameters (current density, applied voltage and HF concentration) are investigated, and a new technique of micromachining using macro porous silicon is presented.
Abstract: This paper presents a new technique of micromachining using macro porous silicon. Macro porous silicon is made by electrochemical etching in hydrofluoric acid. The etch rate and the morphology of the etched surface as a function of etch parameters, (current density, applied voltage and HF concentration) are investigated. Optimization of these parameters makes it possible to fabricate a micromechanical structures such as 45 micrometer deep, 3 micrometer wide and 8 micrometer pitch trenches. Furthermore the diameter of the pore is easy to control by adjusting the current density. During the pore formation an increase in the current density leads to an increase in the pore diameter. This does not effect the diameter of existing pores. This connection of the pores under the structure can be achieved. In this way, various kinds of single crystal silicon micromachined structures can be fabricated.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: The design, modeling, and verification of a MEMS silicon torsion mirror for applications in laser printing is presented and sensitivity analysis for translation versus rotation is performed in order to optimize the mirror design for a raster output scanner (ROS) optical system.
Abstract: This paper presents the design, modeling, and verification of a MEMS silicon torsion mirror for applications in laser printing. It begins with a description of the torsion mirror design, followed by detailed discussions of modeling and verification of the design. A coupled electro-mechanical computer-aided-design software package MEMCAD is used to perform both electrical and mechanical analysis of the mirror under different applied voltages. The MEMCAD modeling results are then post-processed through a program, which retrieves the displacement components of nodes from MEMCAD output and fits a quadratic surface to the deformed reflecting mirror surface. This approximated surface is to be used later in an optical modeling package to analyze the optical performance of the device. The post-processed results are verified by experiential measurements. The first six natural modes of the mirror are determined and are given to help understand the mechanical response of the mirror to different excitation frequencies, Finally, with the aid of MEMCAD, sensitivity analysis for translation versus rotation is performed in order to optimize the mirror design for a raster output scanner (ROS) optical system.
TL;DR: In this paper, the authors compared measured to modeled stress-induced curvature of simple piston micromirrors using IntelliCAD, a commercial CAD system for MEMS.
Abstract: This paper compares measured to modeled stress-induced curvature of simple piston micromirrors. Two similar flexure-beam micromirror designs were fabricate using the 11th DARPA-supported multi-user MEMS processes (MUMPs) run. The test devices vary only in the MUMPs layers used for fabrication. In one case the mirror plate is the 1.5 micrometers thick Poly2 layer. The other mirror design employs stacked Poly1 and Poly2 layers for a total thickness of 3.5 micrometers . Both mirror structures are covered with the standard MUMPs metallization of approximately 200 angstrom of chromium and 0.5 micrometers of gold. Curvature of these devices was measured to within +/- 5 nm with a computer controlled microscope laser interferometer system. As intended, the increased thickness of the stacked polysilicon layers reduces the mirror curvature by a factor of 4. The two micromirror designs were modeled using IntelliCAD, a commercial CAD system for MEMS. The basis of analysis was the finite element method. Simulated results using MUMPs 11 film parameters showed qualitative agreement with measured data, but obvious quantitative differences. Subsequent remeasurement of the metal stress and use of the new value significantly improved model agreement with the measured data. The paper explores the effect of several film parameters on the modeled structures. Implications for MEMS film metrology, and test structures are considered.
NEC1
TL;DR: In this article, a monolithic 256 X 256 bolometer-type uncooled IR detector array is presented that utilizes surface micromachining technology, which is composed of two parts, a silicon readout integrated circuit in the lower part and suspended microbridge structures in the upper part.
Abstract: A process for fabricating a monolithic 256 X 256 bolometer-type uncooled IR detector array is presented that utilizes surface micromachining technology. Each pixel of the device is composed of two parts, a silicon readout integrated circuit in the lower part and suspended microbridge structures in the upper part. The device is based on vanadium oxide bolometer films, which typically exhibit a temperature coefficient of resistance of -2 percent K. The vanadium oxide film is subject to damage, especially during wet etching of the sacrificial layer. Hence, the material and deposition process of the passivation layer for vanadium oxide film were investigated toward attaining a damage-free and flat microbridge structure. This was achieved by adjusting both the thickness of the passivation layer and the stresses in the electrode and passivation layers. The stiction problem of the microbridge structure was solved, by investigating drying conditions after etching of the sacrificial layer. Since each pixel has a cavity structure of (lambda) /4 to absorb IR radiation of the wavelength (lambda) , the spectral response of the pixel was measured in the wavelength range of 2 to 12 micrometers . The interference characteristics can clearly be seen. From responsivity measurements both in vacuum and at one atmosphere, the thermal time constant, thermal mass, and thermal conductance were estimated.
TL;DR: In this article, the authors describe the fabrication and testing of plastic fluidic connectors suitable for the assembly of multichip microfluidic systems, which are inherently planar for ease of connection to flat substrates and are constructed using conventional batch lithographic techniques.
Abstract: This paper describes the fabrication and testing of plastic fluidic connectors suitable for the assembly of multichip microfluidic systems. The connectors basically consist of a series of 50-200 X 20 micrometers 2 capillaries embedded in a 70 micrometers -thick flexible polyimide substrate with large access holes ion both ends. The capillary walls and the connector exterior are coated with a thin layer of p- xylylene providing a high degree of chemical inertness and biocompatibility. These flexible connectors are inherently planar for ease of connection to flat substrates and are constructed using conventional batch lithographic techniques. The connector flow characteristics were tested in nitrogen gas and water. Multiple channel connectors with 3 and 5 capillaries 1.3-4.0 cm-long were constructed successfully.
TL;DR: The third generation of the optical correlator (MROCTM III) includes a ferro-electric liquid crystal (FLC) spatial light modulator (SLM) device in both the input plane and the filter plane, and an improved block design that results in both high light efficiency and very fast operational speed.
Abstract: The military has a requirement for small, low-power, low- cost pattern recognition systems that are capable of locating and identifying high value hostile targets. Miniature optical correlators can perform 2D pattern recognition at greater rates than digital platforms of equivalent size, power and/or weight. The patented miniature ruggedized optical correlator (MROC) can be built to meet the environmental, size, power, and weight requirements of military and rugged commercial applications, and at a cost that will permit wide deployment of the capability. The second version of the MROC correlator consists of a ferroelectric liquid crystal device in the input plane for high light efficiency and incorporates a reflective magneto optic spatial light modulator device in the filter pane for very high speed operation. The correlator has a volume of approximately 20 cubic inches. The MROC module, which includes all drive electronics and interfaces, is a 6U VME module that occupies 5 VME card slots. In this paper we will provide a brief review of the MROC construction and present sample results obtained from the MROC II breadboard. Initial tests demonstrated very high correlation levels, i.e. excellent discrimination, at pattern matching rates of 1920 per second on visible and simulated LADAR images of military vehicles and digital images of fingerprints.
TL;DR: In this article, the authors have demonstrated micromachined microphones with hybrid JFET amplifier circuitry with frequency response extending to 100 KHz, and voltage sensitivity of approximately 2.0 pF.
Abstract: Small, low cost microphones with high sensitivity at frequencies greater than 20 KHz are desired for applications such as ultrasonic imaging and communication links. To minimize stray capacitance between the microphone and its amplifier circuit, process compatibility between the microphone and on-chip circuitry is also desired to facilitate integration. In this work, we have demonstrated micromachined microphones packaged with hybrid JFET amplifier circuitry with frequency response extending to 100 KHz, and voltage sensitivity of approximately 2.0 mV/Pa from 100 Hz to 10 KHz, and 16.5 mV/Pa at 30 KHz with a bias voltage of 8.0 V. The microphones are fabricated with membranes and fixed backplates made of low temperature plasma-enhanced chemical vapor deposited (PECVD) silicon nitride. Because the maximum temperature of the fabrication process is 300 degrees Celsius, microphones may be built on silicon wafers from any commercial CMOS foundry without affecting transistor characteristics, allowing integration with sophisticated amplifier circuitry. Low stress silicon nitride deposition was used to produce membranes up to 2.0 mm diameter and 0.5 micrometer thickness with plus or minus 0.10 micrometer flatness. The excellent planarity of both the diaphragm and the backplate, combined with a narrow sense gap (approximately 2 micrometers) results in high output capacitance (up to 6.0 pF). The high output capacitance results in noise spectral density which is approximately 3x lower than silicon diaphragms microphones previously fabricated by the authors. Diaphragms with corrugations were fabricated to relive tensile stress, to increase deflection per unit pressure and to increase deflection linearity with pressure.
TL;DR: In this article, a tensile tensile test was performed on micro-fabricated samples of single crystal silicon, nickel or nickel-iron alloys using newly developed testing devices.
Abstract: Micromaterial's parameters, such as stiffness constants, critical values and fatigue limits are determined with mechanical tests on microfabricated samples Single crystal silicon, nickel or nickel-iron alloys are investigated using newly developed testing devices In the microsample tensile test, force and elongations are measured independently with high accuracy 10-5 N is the resolution of the force measurement with a precise balance, Elongations down to 10 nm are resolved by analyzing light optical microscope images of the testing region with the least square template matching algorithm The stiffness constants obtained from the tensile test are in excellent agreement with the results of the vibration tests In addition, Q-factor measurements are performed, using a phase-locked loop for precise frequency stabilization The same technique is applied for fatigue experiments, in which rack growth is measured with a resolution of 15 nm Using a new apparatus, torsion tests are performed: a microfabricated sensor is used to quantify the applied torque and the twist angle is determined from the reflection of a laser beam, measured with a photodiode The theoretical analysis presented in this paper concerns two typical problems of microstructure design: the stress concentration at sharp notches in single crystal silicon microstructures and the process induced anisotropy in LIGA structures© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering Downloading of the abstract is permitted for personal use only
TL;DR: In this article, a multi-level micro-electrode structure was produced using excimer laser ablation techniques to obtain devices for the electro-manipulation of bioparticles using traveling electric field dielectrophoresis effects.
Abstract: Multi-level micro-electrode structures have been produced using excimer laser ablation techniques to obtain devices for the electro-manipulation of bioparticles using traveling electric field dielectrophoresis effects. The system sued to make these devices operates with a krypton fluoride excimer laser at a wavelength of 248 nm and with a repetition rate of 100Hz. The laser illuminates a chrome-on-quartz laser at a wavelength of 248nm and with a repetition rate of 100Hz. The laser illuminates a chrome-on-quartz mask which contains the patterns for the particular electrode structure being made. The masks then imaged by a high-resolution lens onto the sample. Large areas of the mask pattern are transferred to the sample by using synchronized scanning of the mask and workpiece with sub-micron precision. Electrode structures with typical sizes of approximately 10 micrometers are produced and a multi-level device is built up by ablation of electrode patterns and layering insulators. To produce a traveling electric field suitable for the manipulation of bioparticles, a linear array of 10 micrometers by 200 micrometers micro- electrodes, placed at 20 micrometers intervals, is used. The electric field is created by energizing each electrode with a sinusoidal voltage 90 degrees out of phase with that applied to the adjacent electrode. On exposure to the traveling electric field, bioparticles become electrically polarized and experience a linear force and so move along the length of the linear electrode array. The speed and direction of the particles is controlled by the magnitude and frequency of the energizing signals. Such electromanipulation devices have potential uses in a wide range of biotechnological diagnostic and processing applications.
TL;DR: Comparison of imagery collected during night driving including: low-light CCD visible imagery, intensified-CCDvisible imagery, uncooled long-wave IR imagery, cryogenically cooled mid-waveIR imagery, and visible/IR dual-band imagery fused for gray and color display is compared.
Abstract: MIT Lincoln Laboratory is developing new electronic night vision technologies for defense applications which can be adapted for civilian applications such as night driving aids. These technologies include (1) low-light CCD imagers capable of operating under starlight illumination conditions at video rates, (2) realtime processing of wide dynamic range imagery (visible and IR) to enhance contrast and adaptively compress dynamic range, and (3) realtime fusion of low-light visible and thermal IR imagery to provide color display of the night scene to the operator in order to enhance situational awareness. This paper compares imagery collected during night driving including: low-light CCD visible imagery, intensified-CCD visible imagery, uncooled long-wave IR imagery, cryogenically cooled mid-wave IR imagery, and visible/IR dual-band imagery fused for gray and color display.
TL;DR: In this article, an electrothermal model of an electrically heated polysilicon microbridges was used to simulate the behavior of a device and its control/sensing electronics.
Abstract: Fully CMOS-compatible, surface-micromachined polysilicon microbridges have been designed, fabricated, and tested for use in catalytic, calorimetric gas sensing. To improve sensor behavior, extensive electro-thermal modeling efforts were undertaken using SPICE. The validity of the SPICE model was verified comparing its simulated behavior with experiment. Temperature distribution of an electrically heated microbridges was measured using an infrared microscope. Comparisons among the measured distribution, the SPICE simulation, and distributions obtained by analytical methods show that heating at the ends of a microbridges has important implications for device response. Additional comparisons between measured and simulated current-voltage characteristics, as well as transient response, further support the accuracy of the model. A major benefit of electro- thermal modeling with SPICE is the ability to simultaneously simulate the behavior of a device and its control/sensing electronics. Results for the combination of a unique constant-resistance control circuit and microbridges gas sensor are given. Models of in situ techniques for monitoring catalyst deposition are shown to be in agreement with experiment. Finally, simulated chemical response of the detector is compared with the data, and methods of improving response through modifications in bridge geometry are predicted.