A tuning fork vibration stand

Summary The described tuning fork vibration stand provides the possibility of dynamic calibrations of accelerometer transducers and indicators, and also of checking the operational capabilities of components and their combinations of small weight under vibrational accelerations reaching 500 g's at fixed, predetermined frequencies.     

A traveling-wave, modified ring linear piezoelectric microactuator with enclosed piezoelectric elements--the "scream" actuator

A 1.8 cc silent bidirectional traveling-wave, self-moving linear microactuator is shown to be capable of generating a sliding velocity of 0.22 m/s and sliding force of 1.1 N. Through the use of computational analysis in the actuator's design, the vibration characteristics were improved in order to obtain a better actuator. The generation of a radial traveling wave about the circumference of the actuator, akin to a ring, is shown to exist despite the unusual shape, and the presence of traveling wave motion along the output face also is shown to exist. By using short-time sinusoidal signals, slider displacements as small as 82 nm were obtained from the actuator, and by using direct current (DC) input, displacements of up to /spl plusmn/107 nm were obtained, suggesting a way to obtain subnanometer positioning accuracy over arbitrary sliding distances. By reversing the phase between the paired driving signals, the direction of motion was reversed at up to 300 Hz; the slider displacement and velocity was found to be inversely proportional to the phase-reversal rate, and the slider's peak velocity and maximum thrust force were directly proportional to the phase between the driving signals. The output force and velocity of the actuator was fairly insensitive to the input frequency, giving measurable motion between 132.5 and 141.5 kHz, but was sensitive to the input voltage, requiring at least 38 V input for operation, and was approximately quadratically dependent on the applied preload centered about 2.25 N.     

Analysis of shaking beam actuator for piezoelectric linear ultrasonic motor

In this paper, piezoelectric linear ultrasonic motors (PLUM) have been investigated on the elliptic trajectory of a contact point in shaking beam, which has been accomplished by two resonance vibration modes of the actuators. The actuators have generated the vibration modes, longitudinal and flexural, by two longitudinal mechanical vibrations with phase difference of pi/2. Modal and harmonic analysis of the shaking beam actuator were performed by the finite element method (FEM) to calculate a resonance frequency and a modal shape and to perform harmonic response. Experimental results proved that a contact point of the PLUM tends to move with an elliptic trajectory.     

A single active nanoelectromechanical tuning fork front-end radio-frequency receiver

Nanoelectromechanical systems (NEMS) offer the potential to revolutionize fundamental methods employed for signal processing in today's telecommunication systems, owing to their spectral purity and the prospect of integration with existing technology. In this work we present a novel, front-end receiver topology based on a single device silicon nanoelectromechanical mixer-filter. The operation is demonstrated by using the signal amplification in a field effect transistor (FET) merged into a tuning fork resonator. The combination of both a transistor and a mechanical element into a hybrid unit enables on-chip functionality and performance previously unachievable in silicon. Signal mixing, filtering and demodulation are experimentally demonstrated at very high frequencies (?>?100?MHz), maintaining a high quality factor of Q?=?800 and stable operation at near ambient pressure (0.1?atm) and room temperature (T?=?300?K). The results show that, ultimately miniaturized, silicon NEMS can be utilized to realize multi-band, single-chip receiver systems based on NEMS mixer-filter arrays with reduced system complexity and power consumption.     

Microengineered silicon double-ended tuning fork resonators

Micromachined silicon sensors employing resonant sensing offer many potential performance benefits over alternative piezoresistive and capacitive techniques. Resonant devices are, however inherently more complicated to design and fabricate. This article provides a brief overview of the principles of resonant sensing and describes a design study involving double-ended tuning-fork (DETF) resonant structures that overcome many practical difficulties due to their dynamically balanced design and mode of operation. The optimum mode is a lateral vibration in the plane of the wafer and this paper also reports a simple method for exciting and detecting lateral vibrations without compromising the degree of dynamic balance of the structure. Test devices have been fabricated in single-crystal silicon     

A flexure-based electromagnetic linear actuator

This paper introduces a novel nano-positioning actuator with large displacement and driving force, termed a flexure-based electromagnetic linear actuator (FELA). It mainly comprises an electromagnetic driving scheme and flexure-supporting bearings that provide infinite positioning resolution and highly repeatable motion. In this work, analytical modeling of the proposed electromagnetic scheme and flexure mechanism is presented. Solutions obtained from each model are evaluated by the experimental studies conducted on a FELA prototype. This prototype achieves a stroke of 4?mm with a positioning accuracy of ± 10?nm. With direct force control, it generates various force profiles with a force-current ratio of 60?N?A(-1) and an accuracy of ± 0.3?N. Such capabilities make FELA a promising solution for realizing ultra-high precision layer-over-layer fabrication in the nano-imprinting process.     

A hysteresis model for a stacked-type piezoelectric actuator

The hysteresis nonlinearity in piezoelectric materials brings difficulties in controlling the systems. In order to mitigate the effect of hysteresis, such nonlinearity needs to be characterized and modeled under different load circumstances. For this purpose, the actuator is modeled in terms of a mass-spring-damper system utilizing the stop operator as one of the operators of the Prandtl-Ishlinskii (PI) model. Merging the structural model with the nonlinear hysteresis model, we observe that the results demonstrate better correspondence to the measured output compared to that of the classical PI model for a wide range of working conditions, i.e., different input frequency and amplitude.     

A study of quartz tuning fork resonators in the second flexuralmode

Quartz tuning fork resonators in the second flexural mode have been studied in less detail than those in the fundamental mode. It is necessary for quartz tuning fork resonators in the second flexural mode to be carefully designed from the viewpoint of total vibrational system design including the mounting leads and capsules, since vibration in the base portion of quartz tuning forks is more readily transmitted to the mounting leads and the capsules as a result of the larger amplitude in the base portion in the second flexural mode than in the fundamental mode. We will discuss here the characteristics in detail on the basis of experimental data and theoretical analysis. Considerations are presented in order to achieve optimal design     

音叉振动式微机械陀螺弹性梁的研究

以一种音叉振动式微机械陀螺为研究对象,建立了四自由度微机械陀螺动力学模型,重点分析了驱动微弹性梁和检测微弹性梁刚度较大方向的微弹性系数对微机械陀螺动力学性能的影响.设计了三段检测梁和两段驱动梁并推导出其微弹性系数公式,建立了微弹性梁的评价函数,通过实例解析对微机械陀螺动力学性能进行了优化.结果表明:优化后的微机械陀螺具有较好的健壮性和较高的灵敏度.此研究结果适用于音叉式微机械陀螺,而且对其它MEMS器件的设计具有重要的参考价值.     

Longitudinal-bending mode micromotor using multilayer piezoelectric actuator

Longitudinal-bending mode ultrasonic motors with a diameter of 3 mm were fabricated using stacked multilayer piezoelectric actuators, which were self-developed from hard lead zirconate titanate (PZT) ceramic. A bending vibration was converted from a longitudinal vibration with a longitudinal-bending coupler. The motors could be bidirectionally operated by changing driving frequency. Their starting and braking torque were analyzed based on the transient velocity response. With a load of moment of inertia 2.5 x 10(-7) kgm2, the motor showed a maximum starting torque of 127.5 microNm. The braking torque proved to be a constant independent on the motor's driving conditions and was roughly equivalent to the maximum starting torque achievable with our micromotors.     

Vibration analysis of cubic rotary-linear piezoelectric actuator

Cubic design of a stator in a rotary-linear piezoelectric actuator is sophisticated and interesting, but the vibration theory of the cubic stator remains unclear when using the finite element method (FEM). In this paper, we analyze the vibration behavior of the cubic stator by applying the energy method, which distinguishes the component of mechanical energy. By changing the design of the stator (especially the length in the direction of the through-hole axis), we clarify how the vibration modes are in accordance at one equal frequency in cubic shape. The behavior of the vibration modes is discussed using conventional vibration theory of a beam and a plate.     

A multilayer inplane bending piezoelectric actuator for dual-stage head-positioning control system

A novel multilayer in-plane bending piezoelectric actuator, called a multilayer split-morph, was designed and fabricated by thick-film screen-printing technology for a dual-stage head-positioning actuator system in a hard disk drive. The design, operation and theoretical principles have been described. The electromechanical performance of the fabricated actuators has been evaluated. The actuation stroke of the actuator is in inverse proportion to the thickness of the piezoelectric layer. The highest displacement/voltage sensitivity of 0.154µmV^-1 is achieved in a trapezoidal multilayer split-morph with a thickness of 35 m in each piezoelectric layer. The corresponding fundamental resonance frequency of the sway mode is high at 47 kHz in the trapezoid actuator with dimensions of 10.14 mm length, 3.08 mm and 1.54 mm widths of the two parallel sides of the trapezoid. The multilayer split-morph was designed to integrate directly onto a modified suspension load beam. With the combined attractive performances indicated above, the batch fabricated multilayer split-morph can provide a low-cost but promising solution for achieving very high track densities in a hard disk drive by implementing a high performance dual-stage head-positioning actuator system.     

A smooth impact rotation motor using a multi-layered torsional piezoelectric actuator

A smooth impact rotation motor was fabricated and successfully operated using a torsional piezo actuator. Yoshida et al. reported a linear type smooth impact motor in 1997. This linear motor demonstrated a high output force and a long stroke. A superior feature of the smooth impact drive is a high positioning resolution compared with an impact drive. The positioning resolution of SIDM (smooth impact drive mechanism) is equal to the piezo displacement. The reported positioning resolution of the linear type was 5 nm. Our rotation motor utilized a torsional actuator containing multi-layered piezoelectric material. The torsional actuator was cylindrical in shape with an outer diameter of 15 mm, an inner diameter of 10 mm, and a length of 11 mm. Torsional vibration performance was measured with a laser Doppler vibrometer. The obtained torsional displacement agreed with the calculated values and was sufficient to drive a rotor. The rotor was operated with a saw-shaped input voltage (180 V; 8 kHz). The revolution direction was reversible. The maximum revolution speed was 27 rpm, and the maximum output torque was 56 gfcm. In general, smooth-impact drives do not show high efficiency; however, the level of efficiency of our results (max., 0.045%) could be increased by improving the contact surface material. In addition, we are studying quantitative consideration, for example, about the optimum pre-load or frictional force.     

Compensation of parasitic effects for a silicon tuning fork gyroscope

This paper refers to a silicon micromachined tuning fork gyroscope, which is driven via two piezoelectric thin film actuators. The device responds to an external angular rate by a torsional motion about its sensitive axis due to the Coriolis effect. The shear stress in the upper torsional stem, which is proportional to the angular rate, is detected via a piezoresistive readout structure. In addition to the wanted signal corresponding to the angular rate, there are unwanted contributions from the drive motion, e.g., from mechanical unbalances and from asymmetries of the piezoelectric excitation induced by fabrication tolerances. These effects, which disturb the sensor signal with varying contributions in amplitude and phase, have already been examined for capacitive surface micromachined sensors. In this paper, they are identified for a piezoelectrically driven, bulk-micromachined gyro and compared to results of FEM simulations. System-level simulations are performed and show possibilities to compensate the main parasitic effects. Results of eliminating the mechanical unbalance by femtosecond laser trimming are presented and compared with the simulations.     

A transparent polymeric flexure-hinge nanopositioner, actuated by a piezoelectric stack actuator

Nanopositioning using piezoelectric actuation and a flexure mechanism is one of most common methods for nanometre-scale positioning. Generally, flexure mechanism nanopositioners have been made from metal. Thus, their application to various environments needs careful consideration with regard to corrosion and circumference interference. In this study, we propose the concept of a chip-like polymeric flexure-based nanopositioner equipped with piezoelectric actuation. In its design, motion performance was predicted using finite element analysis of deformation and stress, and injection mouldability was considered through an injection moulding simulation to allow for fabrication by injection moulding. A cyclic olefin copolymer nanopositioner was fabricated using a mesoscale injection moulding process. Experiments demonstrated that the developed nanopositioner had a travel range of 15?μm with high linearity and it could be successfully controlled by a proportional-integral-derivative (PID) algorithm including a low-pass filter with a root mean square control error of 3?nm.     

Development of piezoelectric monomorph actuator using electrophoretic deposition

In the present work, investigation of the functional property of piezoelectric graded monomorph actuator systems is presented. The functional graded actuators were fabricated by electrophoretic deposition (EPD) using pure PZT and doped PZT materials. Actuators developed have shown gradual gradient variation in microstructure. It is noted that the trend in microstructural gradient does not represent similar trend in piezoelectric property gradient. The displacement of microstructural graded and both piezoelectric and microstructural graded actuators were measured in the static condition. The latter was also measured under dynamic condition. The results show that the proper gradient distribution of the piezoelectric properties is important to improve the electromechanical performance of the actuator.     

A generalized linear thermoelasticity theory for piezoelectric media

Summary A theory of thermoelasticity for piezoelectric materials which includes heat-flux among the independent constitutive variables is formulated. It is found that the linearized version of the theory admits a finite speed for thermal signals. An equation of energy balance and a theorem on the uniqueness of solution are obtained.     

Electrode design for multimode suppression of aluminum nitride tuning fork resonators

This paper is focused on electrode design for piezoelectric tuning fork resonators.The relationship between the performance and electrode pattern of aluminum nitride piezoelectric tuning fork resonators vibrating in the in-plane flexural mode is investigated based on a set of resonators with different electrode lengths,widths,and ratios.Experimental and simulation results show that the electrode design impacts greatly the multimode effect induced from torsional modes but has little influence on ...     

A single-element thermographic system with laser scanning

A new operating principle for apparatus for the qualitative two-dimensional remote analysis of thermal phenomena is considered. The apparatus enables the thermal distribution of objects to be visualized in the medium infrared frequency spectrum and possesses spatial resolving power when detecting a point object approximately two orders of magnitude higher compared with the classical case. Translated from Izmeritel'naya Tekhnika, No. 11, pp. 46–50, November, 2008.