Piezo Actuator Research Articles

The Design and Development of Inch Worm Type Micro Positioning Stage with X-Z Moving Mechanism including Piezo Actuators

The Design and Development of Inch Worm Type Micro Positioning Stage with X-Z Moving Mechanism including Piezo Actuators

A highly stable monolithic enhancement cavity for second harmonic generation in the ultraviolet.

We present a highly stable bow-tie power enhancement cavity for critical second harmonic generation (SHG) into the UV using a Brewster-cut β-BaB2O4 (BBO) nonlinear crystal. The cavity geometry is suitable for all UV wavelengths reachable with BBO and can be modified to accommodate anti-reflection coated crystals, extending its applicability to the entire wavelength range accessible with non-linear frequency conversion. The cavity is length-stabilized using a fast general purpose digital PI controller based on the open source STEMlab 125-14 (formerly Red Pitaya) system acting on a mirror mounted on a fast piezo actuator. We observe 130 h uninterrupted operation without decay in output power at 313 nm. The robustness of the system has been confirmed by exposing it to accelerations of up to 1 g with less than 10% in-lock output power variations. Furthermore, the cavity can withstand 30 min of acceleration exposure at a level of 3 grms without substantial change in the SHG output power, demonstrating that the design is suitable for transportable setups.

Kinematic characteristics of hollow ball under different braking conditions

The purpose of this article is to evaluate smart fluids influence on braking properties for spherical piezo actuator and to determine the functions for rheological experimental graphs of chosen smart fluids. Braking action and motion are modeled using numerical method, which can also be called a stepped approximation. It can be done using Excel program, which can be found in typical Microsoft Office suite.

DMD 빔 투과 광학계 개선을 위한 서브 마이크론급 압전 정렬 기술 개발

Except for the exposure optical system (optical imaging system + light irradiation optical system), the other field technology has secured the base and some core technologies, but it has a high precision positioning alignment technique of the optical imaging optical system that directly affects the result of fine pattern processing of actual products. There is an urgent need to secure. We have studied the alignment method of aperture array of optical imaging system using piezo element. We developed a jig that can align an aperture array using a piezo actuator, and the exposure results were confirmed by aligning the aperture array with the developed imaging optical system. The conclusion is that the alignment method of the aperture array of the optical imaging system using the piezo element led to good results.

Combining Measurement and Control Functions in the Structure of a Multilayer Piezoelectric Actuator of Nano- and Micro-Motions

The principles of creating precision positioning devices based on the piezoelectric effect were studied. A promising scientific direction in the development of piezo actuators is distinguished – the creation of self-sensing devices simultaneously performing functions of an actuating mechanism (actuator) and primary measuring transducer (feedback sensor). An original structure of an adaptive multilayer piezoelectric actuator of nano- and micro-motions was developed. Its structural scheme is given and its advantages are shown.

Geometric tuning: spectroscopy using whispering-gallery resonator frequency-synthesizers

Continuous fine-tuning of nonlinear processes in whispering-gallery resonators is still in its infancy. We demonstrate an innovative, fast, and compact tuning-method by enlarging a ring-like whispering-gallery resonator made out of lithium niobate with the help of a piezo actuator disk embedded inside the resonator. The radial expansion of the actuator forces the resonator to change its size and shape. This process is much faster than thermal tuning and has the additional benefit of a smaller dispersion. Using just this method to tune the resonator, a second-harmonic process pumped at around 1 μm wavelength can be tuned mode-hop-free over a range of 28 GHz, and an optical parametric oscillator pumped at the same wavelength achieved 4.5 GHz continuous tuning. In addition to presenting and demonstrating this novel concept, the influence of the elasto-optic effect and the refractive-index dispersion are discussed, and an analytic model to predict the wavelength dependent tuning efficiency is presented.

Minimizing open-loop piezoactuator nonlinearity artifacts in atomic force microscope measurements.

Atomic force microscopes (AFMs) are widely used to study molecular interactions with piconewton force sensitivity. In an AFM, interaction forces are measured by reflecting a laser beam off a cantilever onto a position sensitive detector and monitoring cantilever deflection. Precise measurements of interaction forces rely on accurately determining the optical lever sensitivity, i.e., the relationship between cantilever deflection and changes in detector voltage. The optical lever sensitivity is measured by pressing the cantilever against a hard substrate using a piezoactuator and recording the resulting change in detector voltage. However, nonlinearities in the motion of commonly used open-loop piezo actuators introduce significant errors in measured optical lever sensitivities. Here, the authors systematically characterize the effect of piezo actuator hysteresis and creep on errors in optical lever sensitivity and identify measurement conditions that minimize these errors.

In-Situ Electron Microscopy of Cu Movement in MoOx/Al2O3 Bilayer CBRAM during Cyclic Switching Process

Resistive random access memories (ReRAMs) and the conductive bridging RAMs (CBRAMs) are expected as the non-volatile memories of next generation. The switching operation of CBRAM is understood to occur with formation and rupture of the conductive filament of Cu or Ag based on the electrochemical reactions [1]. This was experimentally confirmed by in-situ transmission electron microscopy (in-situ TEM) [2]. The previous in-situ TEM works investigated mainly filament formation in the SET process giving the low resistance state (LRS), and few works have examined the RESET process achieving the high resistance state (HRS) [3-4]. Considering the realistic ReRAM operation, repetitive SET/RESET switching operations are important to be investigated by in-situ TEM, since the results contain information for switching reliability. In practical CBRAM test devices, the bilayer structure of solid-electrolyte and oxide layers has been adopted for good retention, speed and stability [5]. In this study, in-situ TEM was applied to the bilayer CBRAM, and the change of the Cu microstructure were observed during cyclic SET/RESET switching. The origin of device degradation will be briefly discussed. The CBRAM of Pt/Mo/Cu(30 nm)/MoOx(20 nm)/Al2O3(5 nm)/TiN was prepared on a Si wafer. All layers were deposited by conventional sputtering or reactive sputtering using Ar-O2. It was processed to be small devices (less than some hundreds of nanometers) using the focused ion beam (FIB) technique. Samples were set in a special TEM holder with a piezo actuator, and in-situTEM experiments were performed during the SET/RESET switching cycles. An example is shown in Fig. 1, where 47 SET/RESET operations were repeated. In the left panel of Fig. 1(a), I–V switching curves in the 1st and 42th cycles, where the formation and rupture of Cu filament was clearly observed in the TEM images, are compared. Though the resistance in HRS was relatively low, clear hysteretic switching curves are identified in the characteristics. This low HRS resistance may be caused by the redeposits of electrode materials formed during the FIB process. In the right panel of Fig. 1(a), in-situ TEM images extracted from a video of the 42th cycle are shown. Corresponding states are marked in the I–V graph; state-1 of HRS before SET, state-2 of LRS after SET, and state-3 of HRS after RESET. In the region marked with red circle, dark contrast corresponding to the Cu filament appeared/disappeared in the Al2O3 layer after SET/RESET while a little of dark contrast exists in the Al2O3layer both before SET and after RESET. This result means that the resistance change occurred based on the filament model. Comparing two I–V graphs in Fig. 1(a), decreased resistive switching ratio was obtained in the 42nd switching. This gives important information on the endurance failure. The resistance values (@−1 V) in cyclic switching operation are summarized in the left panel of Fig. 1(b), where data in accidental switching-less cycles were omitted. The resistance in the both HRS and LRS gradually decreased and the on/off window became narrow. In the right panel of Fig.1 (b), TEM images of the initial state and after the 37th RESET are compared. The contrast of the central part of the Cu layer gradually turned brighter during 37 switching cycles. On the other hand, the center of the Al2O3 became darker. This indicates that Cu moved into the MoOx/Al2O3layer at SET did not return to the Cu electrode completely even after RESET. This can induce formation of Cu deposit in the switching layer and holes in the Cu electrode. As the result, resistance decreased with the switching cycle, and endurance failure should occur. This suggests power balance of the SET/RESET process should be kept adequately to achieve high endurance in CBRAMs. Acknowledgement This work is supported by JSPS KAKENHI (15H01706, 16H0433906 and 16K18073) and Nanotechnology Platform Program (Hokkaido Univ. and Kyushu Univ.) organized by MEXT Japan.

Using refraction in thick glass plates for optical path length modulation in low coherence interferometry.

In Michelson interferometer setups the standard way to generate different optical path lengths between a measurement arm and a reference arm relies on expensive high precision linear stages such as piezo actuators. We present an alternative approach based on the refraction of light at optical interfaces using a cheap stepper motor with high gearing ratio to control the rotation of a glass plate. The beam path is examined and a relation between angle of rotation and change in optical path length is devised. As verification, an experimental setup is presented, and reconstruction results from a measurement standard are shown. The reconstructed step height from this setup lies within 1.25% of the expected value.

Discrimination of three types of homopolymers in single-stranded DNA with solid-state nanopores through external control of the DNA motion

To achieve DNA sequencing with solid-state nanopores, the speed of the DNA in the nanopore must be controlled to obtain sequence-specific signals. In this study, we fabricated a nanopore-sensing system equipped with a DNA motion controller. DNA strands were immobilized on a Si probe, and approach of this probe to the nanopore vicinity could be controlled using a piezo actuator and stepper motor. The area of the Si probe was larger than the area of the membrane, which meant that the immobilized DNA could enter the nanopore without the need for the probe to scan to determine the location of the nanopore in the membrane. We demonstrated that a single-stranded DNA could be inserted into and removed from a nanopore in our experimental system. The number of different ionic-current levels observed while DNA remained in the nanopore corresponded to the number of different types of homopolymers in the DNA.

Stabilization of infinite dimensional port-Hamiltonian systems by nonlinear dynamic boundary control

The conditions for existence of solutions and stability, asymptotic and exponential, of a large class of boundary controlled systems on a 1D spatial domain subject to nonlinear dynamic boundary actuation are given. The consideration of such class of control systems is motivated by the use of actuators and sensors with nonlinear behavior in many engineering applications. These nonlinearities are usually associated to large deformations or the use of smart materials such as piezo actuators and memory shape alloys. Including them in the controller model results in passive dynamic controllers with nonlinear potential energy function and/or nonlinear damping forces. First it is shown that under very natural assumptions the solutions of the partial differential equation with the nonlinear dynamic boundary conditions exist globally. Secondly, when energy dissipation is present in the controller, then it globally asymptotically stabilizes the partial differential equation. Finally, it is shown that assuming some additional conditions on the interconnection and on the passivity properties of the controller (consistent with physical applications) global exponential stability of the closed-loop system is achieved.

FNN Approximation-Based Active Dynamic Surface Control for Suppressing Chatter in Micro-Milling With Piezo-Actuators

In this paper, an active dynamic surface control (DSC) to suppress regenerative chatter in micro-milling with nonlinear piezo-actuators (PZTAs) as active elements has been developed, where the hysteresis effects of two PZTAs are considered. The main features of the proposed approach are: 1) fuzzy neural networks (FNNs) are applied to approximate the unknown functions, including the uncertain dynamics of the high speed cutting system, the unknown bounding functions related to the time-delayed states, and the control errors introduced during the control design procedure; 2) to avoid the development of the adaptation law for each individual weight of the FNNs, the squared 2-norms of the weight vectors are constructed; 3) the utilization of two decreasing smooth performance functions ensures the boundedness of the tracking errors with the prescribed performance; 4) the Prandtl-Ishlinskii (PI) model is employed to depict the hysteresis effect of the active PZTAs and its inverse construction is adopted to mitigate the nonlinear influence; and 5) the Lyapunov-Krasovskii functional is used to cope with the time-delayed effect of chatter in micro-milling, which plays a pivotal role in developing the active control laws. The developed controller with the employments of Lyapunov-Krasovskii functionals, DSC and the adaptive FNN backstepping design can successfully suppress the chatter in micro-milling, guaranteeing all the signals of the closed-loop system are bounded. Simulation results are provided to verify the effectiveness of the proposed control approach.

Actuators of active tribotechnical systems of the rotor-bearing type

The article describes the perspectives of using active bearings in rotor-bearing systems. The principal scheme of a mechatronic tribotechnical system anв classification of actuators used in such system are shown. Piezo actuators are considered from the point of view of use as actuators in active bearings. The comparative characteristics of different types of actuators

Parabolic matching of hyperbolic system using Control by Interconnection

The structural difference between one-dimensional (1D) hyperbolic and parabolic port Hamiltonian system (PHS) is discussed. Then, using a Control by Interconnection (CbI) approach, a distributed state feedback is designed in order to transform an hyperbolic PHS into a parabolic one, the latter being asymptotically stable and even purely dissipative (with no oscillating modes). Distributed wave damping in 1D vibro-acoustic pipes, using piezo actuators, is considered as an illustration example for the proposed control design.

Application of Extremum Seeking for Time-Varying Systems to Resonance Control of RF Cavities

A recently developed form of extremum seeking for time-varying systems is implemented in hardware for the resonance control of radio-frequency cavities without phase measurements. Normal conducting RF cavity resonance control is performed via a slug tuner, while superconducting TESLA-type cavity resonance control is performed via piezo actuators. The controller maintains resonance by minimizing reflected power by utilizing model-independent adaptive feedback. Unlike standard phase-measurement-based resonance control, the presented approach is not sensitive to arbitrary phase shifts of the RF signals due to temperature-dependent cable length or phasemeasurement hardware changes. The phase independence of this method removes common slowly varying drifts and required periodic recalibration of phase-based methods. A general overview of the adaptive controller is presented along with the proof of principle experimental results at room temperature. This method allows us to both maintain a cavity at a desired resonance frequency and also to dynamically modify its resonance frequency to track the unknown time-varying frequency of an RF source, thereby maintaining maximal cavity field strength, based only on power-level measurements.

Hardware solutions for ITER divertor Thomson scattering

The ITER divertor Thomson scattering (TS) system has been significantly upgraded in the last few years in terms of equipment and experimental setup design. In this paper, we are focusing on lasers, digital filter polychromator and piezo actuators, which could be also useful for other diagnostics. Capabilities of the probing and calibration lasers are specified and compared against ITER requirements. Key features of the digital polychromator design for TS applications are presented and obtained signal-to-noise ratios are discussed. The main reason to use piezo actuators for in-vessel remotely controlled devices is high radiation and magnetic resistance of piezo elements. Piezo actuators of inertial and ultrasonic types were produced and their promising performance for fusion devices was demonstrated.

Traveling wave control of stringed musical instruments

Traveling wave control is a technique in which the energy propagating around a structure in the form of waves can be manipulated directly in order to change the overall dynamic behaviour of the structure. In this research, traveling wave control is applied to a musical instrument string with a view to affecting the timbre of the sounds produced by the string when vibrating. A highly linear custom optical sensor is built which is capable of detecting a wave traveling on a string in a single direction, and a piezo stack actuator is situated under the termination point of the string allowing the reflection of the wave to be manipulated directly. Various controllers are analyzed theoretically in terms of their performance, stability, and musical usefulness. They are then implemented and evaluated in terms of their relevance to the design of new musical instruments.

Analysis of asymmetric resonance response of thermally excited silicon micro-cantilevers for mass-sensitive nanoparticle detection

In this paper, the asymmetric resonance frequency (f0) responses of thermally in-plane excited silicon cantilevers for a pocket-sized, cantilever-based airborne nanoparticle detector (Cantor) are analysed. By measuring the shift of f0 caused by the deposition of nanoparticles (NPs), the cantilevers are used as a microbalance. The cantilever sensors are low cost manufactured from silicon by bulk-micromachining techniques and contain an integrated p-type heating actuator and a sensing piezoresistive Wheatstone bridge. f0 is tracked by a homemade phase-locked loop (PPL) for real-time measurements. To optimize the sensor performance, a new cantilever geometry was designed, fabricated and characterized by its frequency responses. The most significant characterisation parameters of our application are f0 and the quality factor (Q), which have high influences on sensitivity and efficiency of the NP detector. Regarding the asymmetric resonance signal, a novel fitting function based on the Fano resonance replacing the conventionally used function of the simple harmonic oscillator and a method to calculate Q by its fitting parameters were developed for a quantitative evaluation. To obtain a better understanding of the resonance behaviours, we analysed the origin of the asymmetric line shapes. Therefore, we compared the frequency response of the on-chip thermal excitation with an external excitation using an in-plane piezo actuator. In correspondence to the Fano effect, we could reconstruct the measured resonance curves by coupling two signals with constant amplitude and the expected signal of the cantilever, respectively. Moreover, the phase of the measurement signal can be analysed by this method, which is important to understand the locking process of the PLL circuit. Besides the frequency analysis, experimental results and calibration measurements with different particle types are presented. Using the described analysis method, decent results to optimize a next generation of Cantor are expected.

Less-invasive non-embedded cell cutting by nanomanipulation and vibrating nanoknife

The less-invasive non-embedded cell cutting or slicing technique provides opportunities for a bio-study at subcellular scale, but there are few effective solutions available at the current stage. This paper reports a robot-aided vibrating system for less-invasive non-embedded cell cutting and investigates the role of key vibrating parameters in the cell cutting process. First, a nanoknife with sharp angle 5° is fabricated from a commercial atomic force microscope cantilever by focused ion beam etching and a vibrating system is constructed from a piezo actuator. Then, they are integrated with a self-developed nanorobotic manipulation system inside an environment scanning electron microscope. After that, we choose yeast cells as the sample to implement the vibrating cutting and investigate the effect of vibrating parameters (frequency and amplitude) on cell cutting quality. The results clearly indicate that the vibrating nanoknife is able to reduce the cutting force and improve the cutting quality. It is also suggested that the repeated load-unload (impact) cycle is the main reason for the better performance of vibrating cutting. The effect of vibrating parameters at small scale benefits our fundamental understanding on cell mechanics, and this research paves a way for the low-destructive non-embedded cell cutting and promotes the practical cell cutting techniques.

Experimental performance evaluation of smart bimorph piezoelectric actuator and its application in micro robotics

Piezoelectric actuator is one of the most versatile types of smart material based actuators which can be utilized for different industrial applications like robotics, MEMS, micro assembly, biological cell handling, self-assembly and optical component handling in photonics. By applying a potential to piezoelectric based smart actuator, it can produce micro level deflection with large force generation, very fast response and long term actuation as compared to other actuators. The characterization and performance evaluation of the bimorph piezoelectric cantilever beam using novel fuzzy logic controller (FLC) tuned proportional-integral-derivative (PID) system has been carried out where the smart bimorph piezo actuator is used as an active actuator for providing the dexterous behavior during robotic assembly. Fuzzy is introduced for fast tuning of PID and it provides the steady state characteristics. Experimentally, it is verified that the actuator produces steady state behavior of deflection for handling the object. A prototype is developed which shows the potential of handling the light weight objects for assembly.