Maximum Resonance Frequency Research Articles

Vibrational and thermoelastic behavior of punched-beam micro resonators containing odd-number of slots

Thermoelastic quality factor is an important mechanism for determining quality factor of a microelectromechanical system resonator, which works in near vacuum, and the resonant frequency is an important characteristic of a resonator. This paper studies variations of the thermoelastic quality factor and the resonant frequency of three- and five-slotted clamped-clamped beam microelectromechanical system resonators. The study has been done by using three-dimensional simulations based on finite element method by COMSOL Multiphysics. Resonant frequency is a function of stiffness and mass of the beam, therefore punching slots in the beam changes the resonant frequency. In addition, slots usually decrease the amount of coupling between mechanical resonant mode and thermal modes, thus improve the thermoelastic quality factor. The C–C beam lengths are considered to be 30.5 µm, 100 µm, and 400 µm. The results show the resonant frequency and corresponding thermoelastic quality factor of the three-slotted beams are greater than five-slotted beams, and a maximum resonant frequency of the three-slotted beams is achieved when the length of inner slot is about 32%–36% of the beam length.

Wireless passive RFID sensor for pipeline integrity monitoring

This work presents a chipless RFID-based sensor for pipeline integrity monitoring in real-time fashion. The sensor monitors the coating lift-off from the pipeline, which is the initial step in external corrosion of a metal pipe. The sensor has a readout coil and an LC resonator on the passive tag with an interdigitated capacitor. The resonant frequency of the sensor demonstrates a strong relation to the gap between the coating and the metal pipe. The tag is built on a flexible substrate for wrapping around the pipe and to represent the pipe coating. The sensor is conformal, battery-free, and low cost which makes it suitable for pipeline monitoring in harsh environments. The resonator was tuned to 105MHz with a Q factor of ∼115. The sensor demonstrates the maximum resonant frequency change of 11.7%, when 2 Standard Cubic Centimeter per Minute (SCCM) of air lifts the coating; and 7.46% when 4mL of water ingress happens in between the coating and the pipe. This sensor has advantages of inexpensiveness, simplicity, and long lifetime with potential capability of prediction prior to failure in pipeline systems.

C-axis tilted ScAlN shear wave acoustic Bragg reflect resonator for gigahertz viscosity measurement

c-axis tilted ScAlN film is attractive for resonators exciting shear wave ultrasonic. Shear mode resonators are suitable for biomarker sensing and viscosity sensing because shear mode resonators can operate without energy leakage to liquid. These sensors are well known as a QCM (Quartz Crystal Microbalance) consisting of AT-cut quartz crystal which excites shear wave ultrasonic. When the resonator is immersed in liquid, resonant frequency decreases due to the viscosity perturbation layer between the resonator and liquid interface. The rate of resonant frequency decrease depend on the mass ratio of viscosity perturbation layer and the resonator layer. Therefore, thinner high frequency resonator allows high sensitivity viscosity measurement. The maximum resonant frequency of the standard QCM plate is about 30 MHz. On the other hand, c-axis tilted ScAlN film can operates over 1 GHz. The sensitivity of the piezoelectric film sensors are much higher thanthat of the QCM sensors. In this study, we deposited shea...

Active membrane-based silencer and its acoustic characteristics

Abstract A membrane-based silencer using dielectric elastomer absorbers (DEAs) was developed and explored in the present study. Dielectric elastomer, a soft smart material, was used to fabricate this actuator. It has the characteristic of lightweight, high elastic energy density and large deformation under external direct current (DC) or alternating current (AC) voltages. The typical acoustic performances of this membrane-based silencer were experimentally identified using a transmission loss (TL) duct acoustic measurement system. It was found that the resonance peaks of this membrane-based silencer could be controlled by applying different external voltages, a maximum resonance frequency shift of 59.5 Hz for the resonance peaks was achieved which indicated that this membrane-based silencer could be adjusted to absorb the target noise without any addition mechanical part. Furthermore, the resonance shift and multiple resonances mechanisms using DEAs were proposed and discussed which was aiming to achieve multi-peaks noise reduction. The present results also provide insight into the appropriateness of the absorber for possible use as an acoustic treatment to replace the traditional acoustic treatment in the noise reduction technology.

Integrative Performance Analysis of a Novel Bone Level Tapered Implant.

Primary mechanical stability, as measured by maximum insertion torque and resonance frequency analysis, is generally considered to be positively associated with successful secondary stability and implant success. Primary implant stability can be affected by several factors, including the quality and quantity of available bone, the implant design, and the surgical procedure. The use of a tapered implant design, for instance, has been shown to result in good primary stability even in clinical scenarios where primary stability is otherwise difficult to achieve with traditional cylindrical implants-for example, in soft bone and for immediate placement in extraction sockets. In this study, bone-type specific drill procedures are presented for a novel Straumann bone level tapered implant that ensure maximum insertion torque values are kept within the range of 15 to 80 Ncm. The drill procedures are tested in vitro using polyurethane foam blocks of variable density, ex vivo on explanted porcine ribs (bone type 3), and finally in vivo on porcine mandibles (bone type 1). In each test site, adapted drill procedures are found to achieve a good primary stability. These results are further translated into a finite element analysis model capable of predicting primary stability of tapered implants. In conclusion, we have assessed the biomechanical behavior of a novel taper-walled implant in combination with a bone-type specific drill procedure in both synthetic and natural bone of various types, and we have developed an in silico model for predicting primary stability upon implantation.

Design of Reliable Analog DMTL Phase Shifter with Improved Performance for Ku Band Applications

<p>An analog phase shifter based on distributed MEMS transmission line (DMTL) is designed for Ku band applications. Traditional RF MEMS phase shifter comprising 6 switches has limited phase shift of 37.75° due to instability region. A new concept of stopper is incorporated to achieve high phase shift. In the present paper, optimisation of the analog phase shifter is done to increase its phase shift upto 88.63°. Phase shift is a strong function of capacitance ratio which is increased from 1.75 to 2.95. The maximum operating voltage and mechanical resonant frequency for the phase shifter are 16 V and 8.3 KHz, respectively. The switching time is calculated to 56 μs. The simulated insertion loss of the phase shifter is -1.75 dB with return loss of -20.49 dB at 17 GHz. The simulated results are verified with analytical modelling which are in close match.</p>

An investigation into resonant frequency of trapezoidal V-shaped cantilever piezoelectric energy harvester

Power supply is a bottle-neck problem of wireless micro-sensors, especially where the replacement of batteries is impossible or inconvenient. Now piezoelectric material is being used as an additional layer in cantilever beams to harvest vibration energy for self-powered sensors. However, the geometry of a piezoelectric cantilever beam will greatly affects its vibration energy harvesting ability. This paper deduces a remarkably precise analytical formula for calculating the fundamental resonant frequency of trapezoidal V-shaped cantilevers using Rayleigh---Ritz method. This analytical formula, which is very convenient for mechanical energy harvester design based on Piezoelectric effect, is then analyzed using MATLAB as well as finite element methods and validated by ABAQUS simulation. This formula raises a new perspective that, among all the trapezoidal V-shaped cantilevers with uniform thickness, the simplest triangular tapered cantilever, can lead to maximum resonant frequency and highest sensitivity and by increasing the ratio of the trapezoidal bases, the sensitivity decreases.

Analysis for microstructure of MEMS bionic vector hydrophone

The MEMS bionic vector hydrophone, which has advantages of high sensitivity, broad frequency band, vector and high Signal to Noise Ratio(SNR), is one kind of underwater acoustic signal detection device integrating piezoelectricity and MEMS technology. However, to make a further step in improving the predictive accuracy and the resonant frequency of underwater acoustic signal, optimization design of the MEMS hydrophone bionic microstructure is performed with finite element method in this paper. Firstly, it can be learned from theoretical formulas of natural frequency and stress that the natural frequency of bionic microstructure is inversely-proportional to the height of bionic cilia and the beam length, at the same time, is proportional to the beam width and thickness; Instead, the sensitivity is proportional to the bionic cilia height and beam length, and is inversely-proportional to the beam width and thickness. Based on the theoretical analysis, maximum stress curves and resonance frequency curves of sensor under different structural parameters are drawn. Secondly, a static analysis was done with ANSYS software and a response curve of natural frequency and stress was drawn. Finally, the simulation results show that a better performance of high sensitivity and broad frequency band for MEMS hydrophones can be obtained by designing beam length, width, thickness and bionic cilia height and radius as 400, 80, 50, 1000 and 80 m respectively. The simulation results and the theoretical analysis are compared, and the differences between them are analyzed.

Residual stress and electromagnetic characteristics in loop type frequency selective surface embedded hybrid structures

Residual stresses occur in frequency-selective surface (FSS)-embedded composite structures after co-curing due to differences between the coefficients of thermal expansion between composite skins and FSSs. Furthermore, the electromagnetic characteristics may be affected by the deformation of the FSS pattern by residual stresses. Therefore, we studied the changes in electromagnetic characteristics due to the deformation of FSS, using residual stresses to deform loop-type FSS-embedded hybrid composites. We considered the effects of loop-type FSS patterns of equal dimension as well as the stacking sequences of composite laminates on the electromagnetic characteristics of FSSs: Square loop, triangular loop and circular loop. The stacking sequences of composite laminates considered in this study were [0]8, [0/90]4, [±45]4 and [0/±45/90]2. The FSS was located between composite laminates in the middle plane. To determine the residual stresses and deformations in the FSS embedded laminate structures, the thermal loading condition in the finite element analysis was induced by cooling the hybrid structures from 125°C to 20°C based on the cure cycle of the composite. Also, the electromagnetic reflection characteristics of the hybrid structures were predicted using deformed models by residual stresses, considering the effects of stacking sequence of composite laminates. The results showed that the maximum residual stresses and deformations were produced in the [0]8 composites with all three loop-types of FSS pattern. However, the maximum resonance frequency shifts occurred in the square and triangle loop-types with stacking sequence of [0]8, while the maximum resonance frequency shift occurred in the circular loop-type with stacking sequence of [0/±45/90]2.

Tuning the resonant frequency of resonators using molecular surface self-assembly approach.

In this work, a new method to tune the resonant frequency of microfabricated resonator using molecular layer-by-layer (LbL) self-assembly approach is demonstrated. By simply controlling the polymer concentration and the number of layers deposited, precisely tuning the frequency of microfabricated resonators is realized. Due to its selective deposition through specific molecular recognitions, such technique avoids the high-cost and complex steps of conventional semiconductor fabrications and is able to tune individual diced device. Briefly, film bulk acoustic resonator (FBAR) is used to demonstrate the tuning process and two types of LbL deposition methods are compared. The film thickness and morphology have been characterized by UV-vis reflection spectra, ellipsometer and AFM. As a result, the maximum resonant frequency shift of FBAR reaches more than 20 MHz, meaning 1.4% tunability at least. The minimum frequency shift is nearly 10 kHZ per bilayer, indicating 7 ppm tuning resolution. Pressure cooker test (PCT) is performed to evaluate the reliability of LbL coated FBAR. Furthermore, applications for wireless broadband communication and chemical sensors of LbL coated FBAR have been demonstrated.

Resonant-frequency tuning of angular vertical comb-driven microscanner

Abstract The resonant-frequency tuning of a self-aligned angular vertical comb-driven electrostatic microscanner is demonstrated by the electromechanical spring effect. The microscanner is fabricated on a silicon-on-insulator wafer using the plastic deformation of silicon. A tuning electrode is fabricated to be electrically separated from the actuation electrode to tune the resonant frequency by adjusting the applied direct-current voltage bias. The experimentally obtained maximum resonant-frequency shift was 3.2% when the resonant frequency of 3167 Hz is reduced to 3066 Hz when a tuning voltage of 30 V was applied while maintaining the actuation voltage. The method enables facile frequency tuning without any permanent geometrical modification to the microscanner.

Estimation of Steel Rebar Position and Thickness in Concrete Members Using Impact Echo Method

Non-destructive testing methods, unlike typical destructive testing methods that deconstruct or cut the building in case of issues such as pores, heterogeneous material, cracks or any such equivalent issues inside/outside the building. And refer to the testing methods for pores, heterogeneous material, or defectiveness occurring in the specimen without changes or destruction of internal structure using ultrasound, radiation, electromagnetism, fluid, heat, or light. In this study, among such non-destructive testing methods, the impact echo method was used for an experiment to estimate the steel rebar location and thickness in the concrete mock member. The mix was made with design standard strength of 30MPa, and for the steel rebar, diameter 22mm was used on the specimen of 300×370×200 to install spacer on the ground surface, and after separating by 40mm, it was arranged with 130mm and 150mm from the top of the specimen to the top of the rebar in 1 column and 3 rows. The specimen for thickness estimation was manufactured with total length of 1800×300 and 6 varying thicknesses of 150mm, 180mm, 210mm, 240mm, 270mm, and 300mm. As the result of rebar location estimation, the maximum resonant frequency was found to be 11269Hz, 9453Hz,and the rebar location estimates were 127.8mm and 151.8mm, which was relatively accurate with error rate of 1.72% and 1.19% from the actual value. In case of thickness estimation specimen, the error rates comparing actually measured thickness and the average value were 2.2%, 2.2%, 4.6%, 0.9%, 3.8%, and 4.7%, which were relatively accurate with average of 3.1%. Through this study, the applicability of steel rebar location and thickness estimation in concrete members using impact echo method could be confirmed.

Design of a Long Distance Unidirectional Piezoelectric Motor Based on Non-Resonant Inchworm Principle

The advantages of linear piezoelectric motor which has low velocity, large output force, non-electromagnetic disturbance and high response speed are concerned wildly in astronautic industry and manufactural industry. A unidirectional and linear piezoelectric motor has been designed based on these advantages. The stiffness and resonant frequencies of the clamping structure and driving structure are calculated by mathematic model. The characteristics of long distance, slow velocity and large output force are realized. This motor can be used in the equipment which needs long distance, small inertia, large driving force and disposable movement. The stiffness and resonant frequencies of clamping structure and driving structure, no-load characteristic and motion characteristics under different loads are tested in the experiment. The results of the stiffness satisfy the theoretical design. The no-load resonant frequencies are high and the maximum resonant frequency dwindles with increasing load.

Design of a Piezoelectric-Driven Tilt Mirror for a Fast Laser Scanner

Recently, laser scanners have been used for laser processing such as cutting, welding, and grooving, especially in the automotive industry. The laser scanners need a high-speed driving to minimize cracks caused by thermal shock of brittle materials. Therefore, a novel laser processing system that is composed of a laser source and a piezoelectric-driven tilt mirror to control the reflection angle of the laser beam, and a stage equipped with the tilt mirror has been investigated. In this study, a piezoelectric-driven tilt mirror is designed and analyzed for scanning performance to achieve a beam spot of 30 µm, a pattern width of 1 mm, an overlap ratio of 70% of the circle area, and a scanning speed of 1 m/s. Then, structural analysis of the tilt mirror with three piezoelectric actuators is performed to determine the maximum reflection angle and resonance frequency. Finally, a prototype tilt mirror is fabricated and its basic characteristics are experimentally investigated and discussed.

Voltage dependence of subthreshold resonance frequency in layer II of medial entorhinal cortex.

The resonance properties of individual neurons in entorhinal cortex (EC) may contribute to their functional properties in awake, behaving rats. Models propose that entorhinal grid cells could arise from shifts in the intrinsic frequency of neurons caused by changes in membrane potential owing to depolarizing input from neurons coding velocity. To test for potential changes in intrinsic frequency, we measured the resonance properties of neurons at different membrane potentials in neurons in medial and lateral EC. In medial entorhinal neurons, the resonant frequency of individual neurons decreased in a linear manner as the membrane potential was depolarized between -70 and -55 mV. At more hyperpolarized membrane potentials, cells asymptotically approached a maximum resonance frequency. Consistent with the previous studies, near resting potential, the cells of the medial EC possessed a decreasing gradient of resonance frequency along the dorsal to ventral axis, and cells of the lateral EC lacked resonant properties, regardless of membrane potential or position along the medial to lateral axis within lateral EC. Application of 10 μM ZD7288, the H-channel blocker, abolished all resonant properties in MEC cells, and resulted in physiological properties very similar to lateral EC cells. These results on resonant properties show a clear change in frequency response with depolarization that could contribute to the generation of grid cell firing properties in the medial EC.

Nanoliter Droplet Characterization using Vibrating Crystal Sensor with Surface-attached Polymer Hydrogel Coating

This paper presents a novel method for nanoliter droplet characterization using a polymer coated sensor of a low-cost quartz crystal microbalance (QCM). The gold electrode of the crystal sensor was coated by a surface-attached polymer hydrogel film of about 2µm thickness using simple spin casting and photocrosslinking procedure [1,2]. The resonance frequency of the coated crystal sensor was continuously recorded at the sample rate of 2 Hz over 90 seconds before and after loading a micro droplet of filtered double-distilled water. Good repeatability (max. CV = 3.8%) and good linearity (r(x,y)= 0.995) of the maximum resonance frequency shift have been observed during 144 dispenses for 6 different droplet volumes in the range from 3 nl to 13 nl. A calibration line for the measured domain of the maximum frequency shift in relation to droplet mass was established according to the gravimetric calibration of the used dispenser with an ultra-microbalance. © 2012 Published by Elsevier Ltd.

Study of Effect of Geometry Parameters on Piezoelectric Cantilever by Modal and Harmonic Analysis

In this study a Finite Element Analysis for cantilever plate structure excited by proof mass is presented. To investigate the influence of different geometry parameters like thickness, length and width on the maximum deflection and resonance frequency. Configuration of piezoelectric actuators attached to the plate structure in order to identify the optimal configuration of the actuators for selective excitation of the mode shapes of the cantilever plate structure. The Finite Element Modeling based on ANSYS12.0 package using modal analysis and harmonic analysis is used in this study for cantilever plate structure excited by patch type of piezoelectric plates of PZT-5H4E of different geometrical parameters like thickness, length & width on the cantilever beam. To study the maximum deflection , the readings are taken by varying different geometry parameters . With this different geometrical parameters first modal analysis is done to know the different modes shapes and their natural frequencies and the frequency of particular mode shape at which the deflection is maximum. Then in the second stapes Harmonic Analysis is carried out near same frequency and the deflection amplitude is found out. Thus simulation of a cantilever beam is done by varying different thickness of piezoelectric plates and the substrate material. The same simulation is carried for different lengths’ & width. Finally the results are combine presented on graph , which clearly shows the effect of variation of geometry parameters on the beam deflections and accordingly change in natural frequency.

Undersized Implant Site Preparation to Enhance Primary Implant Stability in Poor Bone Density: A Prospective Clinical Study

Achieving primary implant stability in areas with poor bone density is often challenging to the clinician. Previous research has suggested that modified surgical protocols might be beneficial in such situations. The objective of the present clinical study was to evaluate the survival rate of implants placed using undersized implant site preparation in areas with poor bone density. A total of 52 implants were placed in 29 patients. Of the 52 implants, 26 were surgically placed according to the standard drilling protocol (control group) and 26 were placed in low-density bone using an adapted bone drilling method (test group). The maximum insertion torque values and resonance frequency analysis measurements were also recorded. All implants were examined clinically and radiographically at follow-up visits during the study period. Oral hygiene status, bleeding on probing, peri-implant probing depth, and implant survival rate were assessed. According to the survival criteria used in the present study, no failure was recorded, and the overall survival rate was 100% for both groups after 12 months. The mean probing depth was 2.75 ± 0.75 mm in the test group and 2.87 ± 0.79 mm in the control group. The mean insertion torque value was 35.19 ± 4.79 Ncm in the test group and 34.62 ± 5.82 Ncm in the control group. The resonance frequency analysis value was 68.58 ± 4.81 implant stability quotient and 66.69 ± 5.41 implant stability quotient in the test and control groups, respectively. The observed differences were not statistically significant (P > .05). The results of the present study suggest that placement of implants by an adapted drilling technique in sites with poor bone density is beneficial in enhancing primary implant stability and improving the implant survival rate.

Dielectric properties and crystal structure of Mg 2TiO 4 ceramics substituting Mg 2+ with Zn 2+ and Co 2+

Solid solutions of [(Mg, Zn)] 2TiO 4–Co 2TiO 4 were used to prepare [(Mg 1− x Zn x ) 0.95Co 0.05] 2TiO 4 have been fabricated using solid-state synthesis for mobile communications. The effect of Zn 2+ and Co 2+ substitution were to enhance Q × f value and densification sintering at lower temperature compared to Mg 2TiO 4 which sintered at 1450 °C. As an optimal compose, [(Mg 0.5Zn 0.5) 0.95Co 0.05] 2TiO 4 successfully demonstrated a dielectric constant of 18.18, a Q × f of 206,000 GHz and a τ f value of −20.8 ppm/°C sintered at 1225 °C. The maximum quality factor multiples resonant frequency ( Q × f) value of around 2100,000 GHz was obtained for the [(Mg 0.6Zn 0.4) 0.95Co 0.05] 2TiO 4, and added more Zn 2+, the Q × f decrease [(Mg 0.5Zn 0.5) 0.95Co 0.05] 2TiO 4.

Sacrificial bridges for MEMS fabrication

This study discusses sacrificial bridges that are used to release MEMS devices. Before being released, sacrificial bridges connect all the component structures into an integral structure. Solder bump bonding is used to mount the MEMS chip on another chip or a printed circuit board (PCB) and to maintain the alignment among all component structures after removal of the sacrificial bridges. Two types of sacrificial bridges were designed, analyzed and fabricated. The fabrication process—which used low resistivity single crystal silicon (SCS) wafers as the device material—was developed to implement the sacrificial bridges. Novel SCS through silicon vias (TSVs), which interconnect stacked chips, was made using the same process. An electrostatic comb drive actuator was fabricated and mounted onto a PCB. The fabricated actuator was tested to demonstrate the feasibility of the fabrication process, sacrificial bridges and SCS TSVs. The results show that the actuator worked well. Its maximum displacement and resonant frequency were 69.9 µm and 406 Hz, respectively. This method is promising for the delivery of a novel 3D system in package for MEMS devices.