Modeling for the Piezoelectric Valve Free Pump

The operating principle of the piezoelectric valve-free (PEVF) pump is based on the unique diffuser nozzles, which provide preferred directions for the liquid flow as shown in Figure 7.3. This pump consists of a cylinder with piezoelectric membrane, which acts like a movable piston. The piezoelectric membrane is made of a piezoelectric element and a support disk. The movement of the piezoelectric Figure 7.3 Piezoelectric MP. (a) Schematic diagram of the piezoelectric MP and (b) structural...

Insulation and Passivation Layer Materials

Silicon nitride is a special form ofnitride ceramic and is widely used as an insulation layer or passivation layer in the design and fabrication ofRF-MEMS devices such as switches and phase shifters. This material has low value of CTE as well as low thermal conductivity. Silicon nitride has a dielectric constant of 6.7, which remains pretty constant over the 10-60 GHz frequency range. This material has very high resistively greater than 1012 V from room temperature to 200 C, and thus can be...

Design Parameters and Fabrications Techniques for a VBand MEMSFilter

The tuning of the mm-wave MEMS-based tunable filters can be achieved using the MIM tuning capacitors and by changing the gap between the MIM elements. Two types of topologies are widely used, namely, the distributed-element type using CPW transmission-line sections and lumped-element type using elements as resonators. Variable MIM capacitors attached at the end of CPW transmission-line segments and fixed spiral type inductors as lumped elements can be used in mm-wave tunable filters. Note...

Piezoelectric Actuation Mechanism

It is important to mention that the piezoelectric actuation is based on inverse piezoelectric effect, although the piezoelectric detection is based on direct piezoelectric effect. Note a piezoelectric material provides its own internal biasing requirement, either due to absence of a center of symmetry in the case of single-crystal materials such as aluminum nitride (AIN) or zinc oxide (ZnO) or due to a permanent polarization present in ferroelectric materials such lead-zirconate-titanate (PZT)....

Para Electronic Ceramic Substrates for MEMS Applications

Para-electronic ceramic (PEC) substrates may play a critical role in future generations of MEMS devices. These substrates have relatively high dielectric constants, extremely low values of CTE, and exceptionally high unloaded Q's (Qun) and are best suited for lower microwave frequency operations. Dielectric properties ofthese substrates are mainly determined by the ionic polarization and the complex dielectric constant can be computed from the classical dielectric dispersion equations. Their...

Introduction

This chapter deals with the packaging, and processing requirements essential for the design and development of MEMS (microelectromechanical systems) devices incorporating nanotechnology (NT) or smart materials. Structural materials most desirable for fabrication of actuator beams are identified. Important properties of materials best suited for MEMS devices for aerospace and space applications are summarized. Critical properties for passivation layers widely used in MEMS switches are described....

Effects of Nonlinearity Generated by MEMS Capacitors

Nonlinearity effects are generated by the movable MEMS membrane of the MEMS variable capacitor, which can introduce very low-level phase noise close to the carrier. The electrostatic (ES) force produced by the applied voltage between the MEMS bridge and the bottom electrode provides the tuning capability of the MEMS varactor. Note the intermodulation (IM) effects are extremely low as compared to other switching elements. The studies further reveal that a two-tone third-order (TTTO)...

Expression for Phase Shift

The phase shift can be written in terms of loaded and unloaded impedances as where c is the velocity of light (meter per second), and Zul and ZL1 are the DMTL characteristic impedances for the low and high bridge capacitance states, respectively 1 . Note that the characteristic impedance of the center conductor as the line width decreases (Figure 6.2), which means larger phase shifts are possible with narrow center conductor width. It is evident from Equation 6.18 that large loading capacitance...

Acoustic Sensors Using Nanotechnology for Underwater Detection Applications

The development and packaging of an underwater acoustic sensor is more difficult than typical microelectronic sensors because of the simultaneous need to protect the sensor or device from external environments, while performing its intended mission. The bio-inspired acoustic sensor must be modeled after the hearing mechanisms in fish and other underwater animals. The sound waves are transferred from the water through the tissues of the aquatic animals. The underwater acoustic sensor will allow...

Nanomaterials for External Support Muscles and Artificial Muscles for Injured Soldiers on the Battlefield

Materials developed using nanotubes are called nanomaterials that have unique thermal, mechanical, and biomedical properties. MIT scientists have been working to develop nanomaterials that can act like exterior support muscles. These support muscles would boost the energy level of a soldier, which would help the soldier to run faster, to jump higher, to lift more weight, and to maintain physical stamina over extended durations. Even the demonstration of these unique capabilities may be several...

Computations of DMTL Parameters

Sample calculations are performed to provide readers rough estimates of magnitudes for Bragg frequency, phase shift, phase delay, loaded line impedance, and various losses associated with phase shifters. Because characteristic impedance of CPW transmission lines is the most important parameter, relevant derivations for various parameters involved will be first discussed in great detail. DMTL can use a varactor diode as a variable capacitance instead of a MEMS bridge structure, if higher losses...

Summary

RF microwave phased shifters can be classified into two distinct categories, namely, absorption type and reflection type. Absorption-type phase shifters are widely used at RF microwave frequencies. But reflection-type phase shifters are best suited for mm-wave applications. A phase shifter is the most critical element in electronically steerable-phased arrays for missile tracking radar, covert communications systems, reconnaissance satellites, missile seeker receivers, and unmanned aerial...

Electrical Properties of Soft and Hard Substrates

Electrical properties of substrates are of critical importance, regardless whether the substrate is soft or hard. The most important properties of microwave substrates are dielectric constant or permittivity, and loss tangent or dissipation loss as a function of frequency and temperature. In addition, surface wave and dispersion losses at mm-wave frequencies must be taken into account. Finally, anisotropy property must be considered, if dimensional stability in the dielectric medium is of...

MEMSBased Gyros and Applications

Precision navigation aids are extremely important for safe navigation, smart munitions, land vehicles used in military operations, robotic applications, airborne radar, and personnel locators. The highest precision inertial measurement units (imu) such as ring-laser gyros and fiber-optic gyros have been in use for several years. These gyros provide a good overall performance, but at the expense of high cost, large size, and excessive power consumption. MEMS designers have developed MEMS-based...

MEMS Technology for Military Systems Applications

RF-MEMS and optical-MEMS devices can play key roles in the design and development of military sensors to meet specific mission requirements. Because of their low-power consumption, compact size, and ultrahigh reliability, MEMS are most suitable in development of sensors for battlefield tanks, surveillance for hostile territory, drone electronics, covert communications, unmanned air vehicles (UAVs), and missiles to shoot down hostile targets. The success of future battlefield conflicts is...

Potential Comb Finger Shapes

Comb drive actuation is the major building block for MEMS devices requiring vertical, lateral, or rectangular displacement. Its operating principle is based on the ES force, which is generated between the interdigital conducting comb fingers of specific shapes as illustrated in Figure 3.20. Potential applications of shaped comb fingers include polysilicon microgrippers, sensing probe devices, forced-balanced accelerometers, actuation mechanism for rotating devices, and RF filters. The most...

MEMS for Wireless Base Stations Satellites and Nanosatellites

MEMS devices and components incorporating NT have revolutionized the wireless, commercial communications, and satellite communications sectors. MEMS-based RF switches, phase shifters, power amplifiers, and printed circuit antennas are best suited for wireless and space communications systems because NT conserves energy and minimum power consumption. Therefore, as a technology that conserves energy and minimizes electrical power consumption, RF-MEMS switches and phase shifters are critical to...

Rfmems Technology for Base Station Requirements

An infrastructure vendor is fully equipped to provide a variety of base station configurations (Figure 1.5) to meet network operator needs. In addition to various air interface standards, such as global system for mobile (GSM) communications, universal mobile telecommunications system (UMTS), and code division multiple access (CDMA), there are also different frequency bands of operations and various RF power levels as illustrated in Figure 1.6. It is important to mention that weight, size, and...

Clamped Clamped Beam Micro Resonator

Important components of this micro-resonator such as the electrode, resonator beam, coupling beam, and the anchors are shown in Figure 8.5b. Critical device parameters include the resonator beam dimensions (length, width, and thickness), electrode width, initial gap, Young's modulus (E), resonator stiffness and mass, bias voltage, and catastrophic voltage. This particular CCB device uses PP capacitive transducers with small gap spacing, which make these resonators to retain high mechanical...

Design Aspects Operating Principle and Description of Critical Elements

A 3-bit distributed MEMS phase shifter consists of three 1-bit phase shifters designated for 180 , 90 , and 45 phase shift, respectively. It is important to mention that each one-bit phase shifter comprises of a CPW transmission-line loaded periodically using several shunt MEMS capacitors. The estimated length of the phase shifter circuit is 11 mm and the device can be fabricated on a glass substrate with dielectric constant of 5.7 to keep the fabrication cost to minimum. The phase shift of the...

Digital Version of the DMTL Phase Shifter with 360 Phase Capability

This particular digital-distributed MEMS phase shifter consists of a high-impedance CPW line capacitive loaded by the periodic installations of discrete varactors, which are formed by the cascaded MEMS bridge sections. This phase shifter design offers significant change in the distributed capacitance with application of small bias voltage (about 12 V) leading to a compact phase shifter with 360 phase capability. The high-capacitance ratio Schottky diode varactor is fabricated using a series of...

Digital MEMS Distributed XBand Phase Shifter

Before embarking on mm-wave distributed MEMS phase shifters, it will be very helpful to get familiarized with the design concept for the X-band distributed MEMS phase shifter. The design is based on the distributed MEMS transmission line (DMTL) cascaded with high-capacitance ratio varactors. These high-capacitance varactors are fabricated using a series combination of MEMS bridge variable capacitors and fixed-value MIM capacitors, as depicted in Figure 6.6. The phase shifter design involves a...

Design Concepts and Performance Parameters of the 165 kHz Oscillator

As stated earlier, the design resonance frequency is 16.5 kHz. A folded-beam comb-transduced MM resonator is selected for the design of this oscillator due to its high-frequency stability against supply voltage fluctuations. It is important to mention that the MM resonator can be switched in and out just by application and removal of the dc bias voltage. Such switching capability can be important in transceiver architectures. The two ports are embedded in a positive feedback loop in series with...

Computations of CPW Line Parameters

The characteristic impedance of the CPW transmission line can be written as where eeff is the effective dielectric constant of the substrate and K(k) and K(k') are the complete elliptic integrals of first kind. Figure 6.2 Plots of elliptic integral of first kind (k less than 0.707 and x less than 1.0). er is the relative dielectric constant of the substrate t is the conductor thickness h is the substrate height or thickness G is the gap on either side of the center conductor as shown in Figure...

MEMS Technology for Medical Applications

Recent design and development of MEMS-based chips by medical research scientists have demonstrated their potential applications for detection and treatment of neurological disorders, epilepsy, seizures, and Parkinson's disease. Neurosurgeons have been successful in quelling epileptic seizures by electrically jolting the vagus verve, one of the twelve pairs of nerves that emerge from the brain instead of spinal cord 9 . Magnetic seizure therapy uses a powerful electromagnet instead of repetitive...

MEMS Technology for Satellite Communications and Space Systems Applications

Wireless satellite communications and space-based sensors are the major beneficiaries of the MEMS technology. Minimum size, power consumption, and high reliability are the critical requirements for both the applications, which can be satisfied by deploying MEMS-based devices and sensors. MEMS technology conserves energy and minimizes power consumption, weight, and size. RF-MEMS devices such as switches, phase shifters, switched antennas, filters, and amplifiers have become critical to...

Free Free Beam HighQ Micro Resonators

As stated earlier that the FFB micro-resonators incorporating the basic flexural-mode beam design offer several benefits such as high stiffness, lower anchor losses, large dynamic range, and high power-handling capability 3 . These performance parameters are most desirable for covert communications applications, where large suppression of interference in adjacent channels is of critical importance. Critical components of an FFB micro-resonator are shown in Figure 8.5a. FFB micro-resonators with...

Fabrication and Material Requirements for the Actuator

Test tower requires the use of structural materials with high values of Young's modulus, which can offer wide displacements ofthe electrochemical actuators needed for fast actuator response. The overall performance ofthe actuator is contingent upon the strain uniformity along the length of the beam and the actuator outer surface of the nanotubes. If all the shells of the MWCNT array could be made to actuate at the same time, the force generated by the electrochemical actuator will be maximum....

Bending Moment of the Cantilever Beam

The bending moment expression can be written as d31 is the piezoelectric material coefficient C N or m V EP is Young's modulus of the piezoelectric material b is the beam width hC is the carrier material thickness V is the actuation or applied voltage Note Equation 2.9 yields excellent results, when the piezoelectric layer thickness is much thinner than the carrier layer thickness. Computed values of tip deflection and bending moment as a function of various parameters for three distinct...

MEMS Varactor Design Aspects and Fabrication Requirements

MEMS technology has the potential of realizing RF variable capacitors with a performance that is superior to conventional solid-state aviator diodes in terms of nonlinearity, flicker noise, and losses. An electrostatically actuated MEMS bridge offers a MEMS parallel-plate PP variable capacitor that can be achieved with simple fabrication, higher yield, and minimum cost. It has built-in capability for tuning over bandwidths exceeding 100 percent at microwave and mm-wave frequencies. A MEMS...

Gauge Factor Computation

As stated earlier that the strain sensors are fabricated from the piezoresistive materials such as silicon or zinc oxide or aluminum nitride. However, silicon is widely used because of its unique properties and availability at minimum cost. There is a fundamental relationship between the resistance change and the mechanical strain developed in the piezoresistive materials. It is important to mention that the resistance change is contingent on the changes in the geometry of the strain gauge. The...

AR Jha PhD

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