Past and current research efforts initiated in the Government and industry for the development of gyroscopes for tactical weapon system applications are discussed in this paper. Spinning mass gyroscopes were used in the early long-range missiles for precision guidance. During the past two decades, tremendous progress has been made in advancing the performance capability of solid-state optical gyroscope for use in tactical weapon systems. A number of Army missile systems currently use ring laser gyroscopes as part of their navigation systems. A few years, ago, the Government awarded several contrasts to industry to develop small, reliable, low-cost fiber optic gyroscopes (FOG) that can operate in military environments. Recently, the Government awarded several contracts for the development of rugged, micro electromechanical systems (MEMS) gyroscopes to support emerging Army missions, which are moving toward low-cost, small diameter precision guided weapons for use against light targets. The RLG, FOG, and the MEMS-based gyroscopes are traded-off in this paper with respect to cost, size and performance for applications in current and future Army missile systems. The status of ongoing MEMS projects at the US Army Aviation and Missile Command will also be discussed.
Future advanced fixed- and rotary-wing aircraft, launch vehicles, and spacecraft will incorporate smart microsensors to monitor flight integrity and provide flight control inputs. This paper provides an overview of Honeywell's MEMS technologies for aerospace applications of sensing and control. A unique second-generation polysilicon resonant microbeam sensor design is described. It incorporates a micron-level vacuum-encapsulated microbeam to optically sense aerodynamic parameters and to optically excite the sensor pick off: optically excited self-resonant microbeams form the basis for a new class of versatile, high- performance, low-cost MEMS sensors that uniquely combine silicon microfabrication technology with optoelectronic technology that can sense dynamic pressure, acceleration forces, acoustic emission, and many other aerospace parameters of interest. Honeywell's recent work in MEMS tuning fork gyros for inertial sensing and a MEMS free- piston engine are also described.
A novel device to directly integrate mechanical motion with electronics on a chip for system integration is designed and fabricated. The device is a laterally movable gate field effect transistor. Here the gate moves parallel to the substrate surface rather than perpendicular to its as in the moving gate transistors reported earlier. Lateral motion results in linear response of device drain current with gate motion. It also makes large motion possible. The device has a variety of applications in smart sensors, actuators and integrated smart systems. A simple fabrication process is developed that is compatible with fabrication of high-aspect ratio structures. The latter give distinct performance improvement. The basic principles of operation of the LMGFET is demonstrate din initial measurements. This, to our knowledge, is the first report on the operation of such a device.
In this paper a new DEM amplifier is designed to amplify the small differential voltage signal, which CM level can be from ground to VDD, using single power supply. Using switched capacitors, the small differential voltage signal can be amplified. In order to eliminate the error caused by the mismatching, dynamic element matching technique has been applied. The simulation result shows that the error caused by mismatching of the capacitors has been significantly reduced to the second order. The DEM SC amplifier has been applied to amplify the thermocouple voltage in an interface circuit for thermocouples.
During the past decade, several new fabrication techniques have evolved which helped popularize micro-electromechanical systems (MEMS), and numerous novel devices have been reported in diverse areas of engineering and science. One such area is microwave and millimeter wave systems. MEMS technology for microwave applications should solve many intriguing problems of high frequency technology for wireless communications. The recent and dramatic developments of personal communication devices forced the market to acquire miniaturized efficient devices, which is possible only by the development of RF MEMS. Semiconductor- polymer based sensor use silicon use silicon or compound semiconductors as inorganic parts with sensitive polymers as insulating, semiconducting or conductive materials. Organic thin film transistor has also been fabricated using this concept. These devices may allow control circuitry to be integrated with 2D or 3D MEMS. Interdigital type RF-MEMS can be designed and fabricated with Interdigital Electrodes (IDE) deposited on either polymer or an inorganic material such as Barium Strontium Titanate (BST). In the case of polymer-based device, we study the capacitance change and calibrate it for desired sensing application. In the inorganic case, we make use of the change in dielectric properties of BST as a function of DC bias. IDE will act like a RF filter and oscillator just like the comb-type RF MEMS devices. These polymeric based devices can be integrated with organic thin film transistors. RF switches, tuners and filters are some of the initial applications of RF MEMS although many others are still under development. In this paper we present the design and development of few devices such as phase shifters, switches and IDT capacitors. It is observed that, dielectric constant of BST thin film changes by more than 50 percent with an applied bias voltage of 25 V dc, which could therefore be easily implemented in RF switch.
Integrated optical components formed by sol-gel process and MEMS devices created on silicon substrate can be used to realize different types of sensing elements for smart structure applications. In this paper we report the fabrication of Ce, Ge and (Ce + Er) doped sol-gel based waveguides on silicon substrates and their optical characterization in terms of light amplification and photosensitivity. We also report results of fabrication and characterization of Bragg gratings in sol-gel based waveguides. The number of layers required for waveguidance and single mode operation has been calculated using the dispersion equations for asymmetric planar waveguides.
This investigation fabricates a laminated-suspension microelectromechanical filter by a fully compatible CMOS process. Experimentally, due to the top metal layer begin used as the etch-resistant mask during the subsequent dry etching. Therefore, this study performs maskless etching with plasma and obtains excellent result including high selectivity and full release of the structure. Additionally, the MEMS filter can be driven by applying low-voltage of around 5 volts and a measured center frequency of around 13.1kHz and a quality factor of around 1871 were obtained for a single-comb resonator operate din air. The filter proposed herein has a monolithic integration capability with the relative electric circuits.
The work reported in this paper is focused on an effective and efficient solution, namely Smart Isolation Mount for Army Guns (SIMAG), to the weapon stabilization and fire control issues facing US Army guns. SIMAG is composed of the optimum integration of two innovative technologies. Vibration Control by Confinement and smart senor/actuator/active control systems. The combined approach may also be applied to a gun barrel to reduce its undesired vibratory motions excited by external and internal disturbances, such as gun firing action. SIMAG reconfigures the distribution and propagation of excess vibration energy and confines vibrations to certain non-critical regions or modes within a structure. Concentrated passive, active, or smart damping elements or cancellation techniques may be applied to more effectively dissipate or cancel the trapped vibrations and to prevent build up in the assembly. As the active elements, an array of collocated, PZT-based sensor- actuator sets is recommended for incorporation in SIMAG. Part of the active elements is used for spatially managing excess vibration energy while the other part is utilized for energy dissipation and cancellation. The preliminary result of our feasibility work on the SIMAG concept is demonstrated via computer simulations. It is shown that the insertion of a preliminary version of SIMAG in a 30mm gun system onboard an attack helicopter reduces the fluctuating loads and deformations measured across the helicopter bottom shell by 40 to 50 percent. SIMAG makes significant progress towards solving the firing control problems with affordable weight and power penalties by compensating for all errors in one of the two places, the turret-aircraft interface or gun barrel. Even thought the initial target application of SIMAG is airborne guns, a modified version can be incorporated into ground armors, such as tanks and humvees.
The combination of Integrated Optics with micro-mechanical structures on silicon offers immense potential for smart structure applications. One such application is sensing and mapping of vibration and vibrational modes. In the present proposal, a cantilever formed by bulk micro machining of (100). Silicon and optical waveguides formed by sol-gel process is considered. Among the various configurations possible, an optical directional coupler located close to foot of the cantilever is analyzed in detail. Analytical and simulation result using optical coupled mode theory to obtain the power transfer that is dependent on cantilever vibrations are presented.
Micro-electro-mechanical (MEMS) technology offers the ability to implement local and independent sensing and actuation functions through the coordinated response of discrete micro-electro-mechanical 'basis function' elements. The small size of micromechanical components coupled with the ability to reduce costs using volume manufacturing techniques opens up significant potential not only in military applications such as flight and engine monitoring and control, but in autonomous vehicle control, smart munitions, airborne reconnaissance, LADAR, missile guidance, and even in intelligent transportation systems and automotive guidance applications. In this program, Luna Innovations is developing a flexible, programmable interface which can be integrated direction with different types of MEMS sensors, and then used to multiplex many sensors ona single optical fiber to provide a unique combination of functions that will allow larger quantities of sensory input with better resolution than ever before possible.
This paper describes recent work in the field of computer vision and relates the results to the much broader class of smart sensors. The paper begins with an overview of recent work concerning the combination of chemical sensors with neural networks, Such devices allow classification of samples into distinct states, forming, to give one example, an electronic nose. These often require a broad selectivity and are formed from small arrays of sensor elements. This is followed by a description of two aspects of the authors' own work in the field of computer vision. One is an automatic control system of a micro robot-based microassembly station using computer vision. The other concerns that automatic recognition of objects regardless of the scale of the object. For the latter, we have shown that when the senor input noise is taken into consideration, a conventional CCD array is unable to provide a robust representation of an object, regardless of scale. In contrast to this, biological based retinal arrays are able to achieve this. The paper concludes with the perspective that all sensor systems are data dependent. This is of little concern if the sensor consists of a single element, but becomes more important as larger arrays are fabricated. These sensor arrays may have to emulate biological systems, in an analogous manner to a retinal camera.
This paper describes the final results of the Applied Research in Remotely-Queried Embedded Microsensors program. The program developed wireless and battery-less embedded strain/temperature gages suitable for embedding in aerospace and other composite structures. The program culminated in a working remotely queried strain rosette/temperature gage and testing of the device in several composite applications. The US Office of Naval Research funded this program to consolidate progress made in earlier programs towards self- contained microsensors.
A novel way to design, synthesize and adjust the reconfigurable dual offset contour beam reflector antenna employing an adjustable subreflector is presented. The work also presents a graphical user interface based computer code that connects the electro-magnetic effects to the mechanical surface deflections. The subreflector surface is described by using the finite element method and the far-field radiation pattern is calculated by reflector diffraction synthesis. The reflector surface shape is adjusted using a set of linear piezoelectric point actuators attached to its back surface, from which the diffraction synthesis code calculates the radiation pattern. An example of this method applied to the contiguous US is also presented. As a future work, a software package will be built where the finite element code and the diffraction synthesis code are combined, and it will be used for advanced actuator placement and reflector design problem.
The fractal antennas with multi-band and multi-functional capabilities have been very actively studied in the recent years. In contrast, the fractal antenna presented here combines properties of the dielectric substrates with the well-known characteristics of fractal patterns, to result in a wideband conformal antenna. The input characteristics of the antenna is experimentally found to be better than -10 dB for a very band of frequencies from MHz to few GHz band. Another important characteristics of the fractal antennas introduced her is the possibility of making a reconfigurable antenna with this approach. Preliminary simulation results for a fractal reconfigurable antenna are presented here.
On many situations the reduction of radar cross section (RCS) is of continued strategic interest, especially with aircraft and missiles. Once the overall RCS of the vehicle is reduced, the reflections from the antennas can dominate. The commonly known approaches to RCS reduction may not be applicable for antennas, and hence special techniques are followed. These include configuring the antennas completely conformal, and using band pass frequency selective surfaces. The use fractal patterns have shown to result in such band pass characteristics. The overall RCS of a typical target body is experimentally found to be reduced when these screens are used. The paper presents the experimental result on the transmission and backscatter characteristics of a fractal FSS screen.
An active diagnostic technique for identifying impact damage in composites is presented. A network of piezoelectric actuators and sensors were built into composites to generate and receive ultrasonic stress waves in the structures. Scattered waves were produced from the damage and were detected by sensors. A signal-processing scheme composed of smoothing filtering a joint time-frequency analysis was applied to minimize noise interference and convert sensor measurements into time-frequency spectrograms for interpretation. An identification method based on time-of- flight information obtained from the spectrograms was developed. Experiments were performed on composites with different configurations. It was demonstrated that the method was able to detect the presence of the damage and characterize the damage to a satisfactory precision. Identification results were verified with X-ray images of the structures.
Serpentine robots offer advances over traditional mobile robots and robot arms because they have enhanced flexibility and reachability, especially in convoluted environments. These mechanisms are especially well suited for search and rescue operations where making contact with surviving victims trapped in a collapsed building is essential. The same flexibility that makes serpentine robots incredibly useful also makes them difficult to design and control. This paper will describe the current status of serpentine robot design and path planning underway in our research group and point towards future directions of research.
Structural health monitoring involves automated evaluation of the condition of the structural system based on measurements acquired from the structure during natural or controlled excitation. The data acquisition and the ensuring computations involved in the health monitoring process can quickly become prohibitively expensive with the increase in size of the structure under investigation. In this paper, we propose a distributed sensing and computation architecture for health monitoring of large structures. This architecture involves a central processing unit that communicates with several data communication and processing clusters paced on the structure by wireless means. With this architecture the computation and acquisition requirements on the central processing unit can be reduced. Two different hardware implementation of this architecture one involving RF communication links and the other utilizing commercial wireless cellular phone network are developed. A simple health monitoring experiment that uses neural network based pattern classification is carried out to show effectiveness of the architecture.
MEMS are currently being applied to the structural health monitoring of critical aircraft components and composites. The approach integrates acoustic emission, strain gauges, MEMS accelerometers and vibration monitoring aircraft components with a known history of catastrophic failure due to fracture. Recently a combination of the need for safety in the air and the desire to control costs is encouraging the use of in-flight monitoring of aircraft components and systems using light-weight, wireless and cost effective microsensors and MEMS. An in-situ aircraft structural health monitoring system, with sensors embedded in the composite structure or surface-mounted on the structure, would permit the timely detection of damage in aircraft. Micromachining offers the potential for fabricating a range of microsensor and MEMS for structural applications including load, vibration and acoustics characterization and monitoring. Such microsensors are extremely small; they can be embedded into structural materials, can be mass-produced and are therefore potentially cheap. The smart sensors are being developed using the standard microelectronics and micromachining in conjunction with novel Penn State wireless communication systems suitable for condition monitoring of aircraft structures in-flight. The main application areas of this investigation include continuos monitoring of a) structural integrity of aging aircraft, b) fatigue cracking, c) corrosion, d) deflection and strain of aircraft structures, wings, and rotorblades, e) impact damage, f) delamination and g) location and propagation of cracks. In this paper we give an overview of wireless programmable microsensors and MEMS and their associated driving electronics for such applications.
We will discuss our work to build, characterize, and scale- up a metallized plastic muscle-like actuator called a Spiral Wound Transducer (SWT). Prototype SWTs have been built using microelectronics fabrication methods. The prototypes have demonstrated large amplitude motion and analog response. The prototypes, though small, have demonstrated forces equivalent to 12 grams for compressions of more than 15 percent at 30 Hz. The size of the SWTs is essentially unrestricted. Our work with commercially available metallized Mylar films to produce much larger, more powerful, and lower cost SWT devices will also be discussed.
This paper reports the results of experimental studies using a bulge tester and accompanying models. The bulge tester applies a load on the backside of the thin film and measures the resulting deflection. The load-deformation data can then be used to establish a mode that can be used to determine Young's modulus and the in-plane stress of the film. A variety of different films are tested under different conditions and the results are compared to theoretical values and to the result of a non-linear finite element model. The approach of the computer model is inverse to the tester. The determined values are used as input for the model and the load-deformation data is the output. The experimental results are found to be in excellent agreement with the numerical prediction. The applicability of using a thin piezoelectric film on top of another film in a window as an actuator is also investigated. The ultimate goal is to create a smart thin film window that can precisely sense and control stretching and/or deflection of the base film. This could be very useful in lithography procedures in order to align and control the mask or particular potions of the mask.
A novel micro-machined valveless diffuser-nozzle micropump is presented in the present paper. The micropump is designed by thermally bubble driven actuation method. This pumping mechanism requires no mechanical moving parts for actuation and control of inlet and outlet. As a result, it requires substantially simplified fabrication process in two wafers, which is compatible with IC fabrication processes. The proposed micropump will provide high actuation stroke than existing micropumps.
Micro Stereo Lithography (MSL) is a poor man's LIGA for fabricating high aspect ratio MEMS devices in UV curable semiconducting polymers using either two computer-controlled low inertia galvanometric mirrors with the aid of focusing lens or an array of optical fibers. For 3D MEMS devices, the polymers need to have conductive and possibly piezoelectric or ferroelectric properties. Such polymers are being developed at Penn State resulting in microdevices for fluid and drug delivery. Applications may include implanted medical delivery system, artificial heart valves, chemical and biological instruments, fluid delivery in engines, pump coolants and refrigerants for local cooling of electronic components. With the invention of organic thin film transistor, now it is possible to fabricate 3D polymeric MEMS devices with built-in-electronics similar to silicon based microelectronics.
Probe manipulation of fine particles has been investigated in our laboratory. The feature of our system is that wide range of voltage, 0-10kV, can be applied between the probe and the substrate. In this method, we can pick up a fine particle at the tip of the probe, carry, place and weld the particle at a predetermined point on the substrate by controlling the applied voltage to the probe. When the particle is picked up, 10-50V is applied. And 2-10kV is applied for the welding. Breaking shear stress of welded particles is measured as follows. A sheet spring, where the strain gauges are stuck, is prepared. One end of the sheet spring is held, and moved to push off the welded particle by the free end. The shear stress is calculated from the output of the strain gauges. The breaking shear stress is 44-71MPa for gold particles welded on a gold substrate. Self- sustaining characters, 'NRIM', are formed from gold particles of 40micrometers as an example of microstructure. Preliminary experiments for the application to the ball grid array are carried out. We also fabricated a slant tower of magnetostrictive particles. It will be used as a micro- actuator in the alternative magnetic field.
This paper presents the fabrication of a micro electromagnetic flow sensor for the liquid flow rate measurement. The micro electromagnetic flow sensor has some advantages such as a simple structure, no heat generation, a rapid response and no pressure loss. The principle of the micro electromagnetic flow sensor is based on Faraday's law. If conductive fluid passes through a magnetic field, the electromotive force is generated and detected by two electrodes on the wall of the flow channel. The flow sensor consists of two permanent magnets and a silicon flow channel with two electrodes. The dimension of the flow sensor is 9 mm by 9 mm by 1 mm. The micro flow channel is mainly fabricated by anisotropic etching of two silicon wafers, and the detection electrodes are fabricated by metal evaporation process. The characteristic of the fabricated flow sensor is obtained experimentally. When the flow rates of water with the conductance of 100-200 (mu) S/cm are 9.1 ml/min and 62 ml/min, the generated electromotive forces are 261 (mu) V and 7.3 mV, respectively.
This paper first presents the fabrication of an electromagnetic microactuator using an electroplated spiral copper coil on a parylene C diaphragm. The parylene is a bio-compatible material and has a very low Young's modulus less than 2.8 Gpa, which makes the large deflection for the low power consumption. The actuator consists of an electroplated coil on the parylene C diaphragm, a small-size permanent magnet and a core. The diaphragm is actuated by the Lorenz force generated by the current through the coil in the magnetic field of the magnet. The size of the actuator diaphragm is 4 by 4 mm2 and 5 micrometers thick. The resistance and inductance of the copper spiral coil are 2 (Omega) and 11 (mu) H at 100 Hz, respectively. The center deflection of the actuator diaphragm is measured with the laser vibrometer. Whenthe current through the coil is 380 mA, the peak-to-peak deflection of the actuator is 143 micrometers below the resonant frequency of 35 Hz. The mechanical sensitivity of the actuator diaphragm is 900 micrometers /A at 10 Hz and 35 Hz, respectively. An electromagnetic microactuator using the electroplated copper coil on the parylene diaphragm is expected to be useful in making a micropump for the bio-medical use.
Deicing of fixed wing aircraft and rotor craft that fly; at lower altitudes has been an area of research interest for many decades. The currently available solutions, though functional, are economically or environmentally inefficient. Some military helicopters have electrical deicing system for rotor blades that use up to 12 kW of power to achieve all weather shear horizontal waves at the ice-substrate interface is proposed. Experiments were carried out using PZT-5A and PZT-8 shear plate actuators bonded to an aluminum plate. A low-temperature chamber was constructed for this purpose. The results indicate that the PZT-8 actuators were able to deice the aluminum plate melting the ice at the interface. Results are presented in the form of tabular data and digital photographs taken of the melting process. The deicing mechanism is discussed.
Microengineering has evolved in the last decade as a subject of its own with the current research encompassing every possible area of devices from electromagnetic to optical and bio-micro electromechanical systems (MEMS). The primary advantage of the micro system technology is its small size, potential to produce high volume and low cost devices. However, the major impediments in the successful realization of many micro devices in practice are the reliability, packaging and integration with the existing microelectronics technology. Microengineering of actuators has recently grown tremendously due to its possible applicability to a wide range of devices of practical importance and the availability of a choice of materials. Selection of materials has been one of the important aspects of the design and fabrication of many micro system and actuators. This paper discusses the issues related to the selection of materials and subsequently their effect on the performance of the actuator. These will be discussed taking micro magnetic actuators and bearings, in particular, as examples. Fabrication and processing strategies and performance evaluation methods adopted will be described. Current status of the technology and projected futuristic applications in this area will be reviewed.
In this paper we describe the development of a CMOS VLSI backplane for use with micromachined silicon nitride membrane mirrors. The backplane consists of an array of 4096 pixels which are addressed by a 6-bit row decoder. Data enters the chip as a 64-bit logic word at standard CMOS 0-5V levels and is converted to 0-50V at the pixel level by an optimized cascade voltage switch logic circuit.
We have developed a novel method for simple and quick fabrication of various 2D photonic crystals consisting o polymer rods arranged regularly in air using molds made by laser light. Square- and honeycomb-lattice photonic crystals, in which the radius of a rod, the spacing between nearest-neighbor rods, and the real part of a dielectric constant of the polymer were 22 micrometers , 90-100 micrometers and 3.7, respectively, were created, and far-IR transmission spectra were measured. The experimental and calculated result agreed with each other, indicating that our samples were genuine photonic crystals. In addition to well-known opaque regions in transmission spectra due to photonic band gaps and optical branches of uncoupled mode, we have discovered that the transmission is suppressed drastically at branches with flat dispersion due to the influence of absorption of light.
This work analyzes to synchronize the phases of micromirror array and operate resonance frequency. The eigenvector, which synchronizes in-phase, can be found via a mass- damping-spring system. The device replaces conventional large area mirror, thus enhancing the working frequency and allowing micromirror arrays to reduce a smaller gap. The torsional micromirror array fabricates using three conventional masks based on bulk-micromachining technology. This work also describes the proposed design in detail. According to our result, the difference between the testing results and theoretical value is within 1 degree.
This paper presents the design, fabrication and evaluation of a conformal Radio Frequency (RF) MEMS Gyroscope, base don surface acoustic wave resonators (SAWR) and surface acoustic wave sensors (SAWS), with very high sensitivity and dynamic range. Most MEMS gyroscopes based on silicon vibratory sensors utilizes the energy transfer between the two vibratory modes suffers serious drawback in producing identical resonating modes and hence to attain a sub-degree per second is quite impractical. This 1 cm X 1 cm gyroscope is working based on the principles of surface acoustic wave (SAW) standing waves on a piezoelectric substrate. The SWAR creates standing wave inside the cavity and the particles at the anti-nodes of standing wave experience large amplitude of vibrations, which serves as the reference vibrating motion for this gyroscopes. Arrays of metallic dots are strategically positioned at the anti- node locations so that the effect of Coriolis force due to rotation will acoustically amplify the magnitude of the waves. The performance of this 74.2 MHz MEMS Gyroscope has been evaluated using geophone setup and rate table setup, which shows very high sensitivity and dynamic range, which is ideal for the conventional applications. Unlike other MEMS gyroscopes, this gyroscope has a planar configuration with no suspended resonating mechanical structures, thereby giving rise to inherent robustness and shock resistance. With its one layer planar configuration, this gyroscope can easily be implemented to the applications requiring conformal mounting on to a surface of interest.
The reports relates to a fluid based accelerometer and inclinometer and more particularly to a transducer which determines acceleration, inclination, position or velocity based on a temperature differential caused by the effect of acceleration on free or natural convection. This device includes a heater a d two temperature sensing elements mounted within a sealed enclosure containing a gas. The thermal sensors and temperature sensors were produced using a commercial CMOS process accelerometer based on above principle has been fabricated and tested.
A monolithic micromachined inertial measurement unit (IMU), which combines three-degree-of-freedom gyroscope and a three-degree-of-freedom accelerometer, is attractive for navigation and guidance. A micromachined gyroscope generally works in a vacuum package to archive a high resolution. By contraries, a package of an accelerometer should provide proper dumping to optimize dynamic response. It is very difficult to fulfill two different package demands in one chip by using conventional package technology. We developed wafer-level silicon cap package technology to solve the problem. The gyroscope is completely sealed in a vacuum silicon cavity by anodic bonding in vacuum. The accelerometer is package din another silicon cavity, but different from the gyroscope, a 'bypass hole' is fabricated in the wall of the cavity. Using this technique, the accelerometer can operate in an air ambient, the damping is controlled by optimizing structure design of accelerometer and change the size of the bypass hole. Consequently, demands of package for both accelerometer and gyroscope are fulfilled. Besides, the silicon cap can protect fragile mechanical structures during post-releasing processing, such as dicing, mounting and wire bonding. Consequently, after the silicon cap is formed, the MEMS wafer can be treated as a common IC wafer. These structures were fabricated with wafer bonding and ICP deep etching technologies, but can be also fabricated by other micromachining technologies.
A MEMS-based fiber optic grating sensor (FOGS) for improving weapon stabilization and fire control has been investigated and developed. The technique overwrites two fiber Bragg gratings (FBGs) onto a polarization-preserving optical fiber core. A MEMS diaphragm is fabricated and integrated with the overlaid FBGs to enhance the performance and reliability of the sensor. A simulation model for the MEMS-FOGS was derived, and simulation results concerning load, angle, strain, and temperature were obtained. The fabricated MEMS diaphragm and the overlaid FBGs are packaged together and mounted on a specially designed cantilever beam system. User-friendly software for sensing system design and data analysis has been developed and can be used to control other sensing systems. The combined multifunctional sensitive. The fully developed sensing system is expected to find applications in fire control, weapon stabilization, and other areas where accurately sensing strain and temperature is critical.
The objective of this paper is to focus on recent efforts to test and characterize the performance of MEMS inertial sensors and the characterization of battery-free embedded sensors in munitions. This paper will also discuss the need to implement and integrate internal wireless communications in conjunction with smart electronics and smart materials in innovative microelectronics designs with built in capability of duplex wireless communications between sensors and telemetry. Embedded wireless telemetry will eliminate wires and the stress on long wire runs between MEMS sensor and processing microelectronics in harsh environments. Further advancements in this wireless area will facilitate the integration of smart sensing, control and actuation with unprecedented capability to permanently embed telemetry as a part of the standard munition components. The embedded wireless telemetry would have built in capability for smart munitions stockpile surveillance, in-flight duplex communication and the capability to communicate to a ground station. Future telemetry links for munitions will have a significant multi-use capability, designed to measure, maintain reliability, predictive surveillance, actuation and remote control functionality.
Flow in microtubes is characterized by the formation of an electrical double layer (EDL), at the fluid-wall interface, and the creation of an electric field that has a retarding effect during pressure-driven fluid flow. Using the 3D form of the Maxwell equations and the Navier-Stokes equations as a starting point, we discuss certain consequences of the theory when applied to the study of the effects of EDL during steady state laminar flow in microtubes. Further, the effects of EDL during periodic laminar flow - caused by a periodic external electric field or a periodic pressure gradient - are considered. Such a scenario is encountered in areas as diverse as microelectronics and the mechanics of blood circulation. Analytical solution of the problem is then given.
In this paper, we present the design and fabrication of MEMS hydrophones on a silicon wafer using standard NMOS process technology. The effects of two MOSFET amplifiers with different W/L ratios on the hydrophone performance are investigated. A piezoelectric polymer, polyvinylidene difluoride, is employed as the sensing material. Acoustic impedance possessed by this piezoelectric material provides a reasonable match to that of water, which makes it very attractive for underwater applications. Measurements of the hydrophone devices were carried out in a pulse tube with a frequency range of 4-10 KHz. The results reveal that the hydrophone comprising a MOSFET with larger W/L ratio provides better sensitivity.
This work is a first step in a study that will determine whether CMOS-compatible magnetically actuated micromachined cantilevers can be used as the principle actuators for fluid pumping in a microfluidic system. In this paper, we repot on the result of a finite element study on the static tip deflections of micro-cantilevers actuated by Lorentz forces. Two different micro-cantilever designs have been studied and it is found that the presence of a folded support arm in one of the configurations increases the static tip deflection three-fold. As well, the presence of a stiff silicon nitride layer on the micro-cantilever surface significantly affects the tip deflections when the layer is 0-50 percent of its original thickness; this outcome is independent of the micro-cantilever geometries studied.
The rotary electro-static micro actuators integrating optimally curved electrodes are proposed to enhance the actuating force-generation capability. The results show that the actuating force-generation capability. The results show that the actuating force generated by the prosed design is more than 5 times greater than the conventional shape for the application of hard disk drive device. Also, the results indicate that, as the smaller gap size is allowable, the force generation capability will be dramatically enhanced. In this design the uniformity in the capacitive gap size is the additional feature to be in favor of fabrication of a micro-actuator.