We present various examples for man-made and biological nano-scale actuators based on oscillations. The basic idea of all such actuators is introducing an asymmetry into the oscillations, which causes a net directed movement of the system over one period of oscillation. In addition to discussing general principles and several examples, we introduce a new concept for a high precision actuator which is based on oscillating rolling. The actuator consists of a sphere that is pushed on a movable substrate. The sphere acts as the drive and the substrate acts as the runner. A varying normal force leads to varying indentation depth and contact area. Together with the inertia of the runner this asymmetry enables accurate control of its displacement. In theory, the actuator works wear less as slip is completely omitted.
This paper presents the design and analysis of a high-speed XYZ nanopositioning stage. The developed stage is composed of a parallel-kinematic XY stage and a Z stage which is nested within the end-effector of the XY stage. To achieve high resonance frequencies, four special flexure modules with large stiffness are employed for the XY stage. These modules are arranged symmetrically to reduce cross-coupling between X- and Y-axis. For the Z stage, a symmetrical leaf flexure parallelogram mechanism is adopted, which has high resonance frequencies and no cross-coupling. Static and dynamic analysis are performed respectively to establish analytical models for the developed XYZ stage. Based on these models, the dimensions of the stage are optimized to maximize the first resonance frequency of the X-and Y-axis. Then, finite-element analysis (FEA) is conducted to validate the performance of the developed XYZ nanopositioning stage. The FEA results reveal that the workspace of the stage is 9.2 μm × 9.2 μm × 3.1 pm and the first resonance frequencies of the stage in three axes are 7.3 kHz, 7.3 kHz and 46.2 kHz, respectively, which agrees with the analytical results.
This paper presents a new method of microfluidic chip fabrication using 3D design and 3D printing techniques. The printed materials are flexible and inexpensive. The fabrication procedure is time-saving and less complex. The water leakage and hydrophilic test are performed to prove the advantages over traditional methods. The flow rates of the printed pump chip have been tested under varied applied pneumatic pressures and pumping frequencies. A maximal flow rate of 16.08 μL/min is achieved at the driving frequency of about 10 Hz at pressure of 30 psi. And a maximal flow rate of 38.60 μL/min is achieved at the driving frequency of about 10 Hz at pressure of 40 psi.
In this paper, an electromechanical energy harvester with resonant frequency of 55.5Hz and ability of scavenging the AC current energy by magnetic field coupling is designed and characterized. The energy harvester consists of a piezoelectric cantilever and a permanent magnet bias. An iron mass is mounted on the free end of the cantilever with the permanent magnet set proximity to it. This structure greatly simplifies the fabrication and installation of the energy harvester. The device is placed close to a wire carrying AC current to couple its alternative magnetic field. The alternative magnetic force on iron mass is enhanced due to the static magnetic field from the permanent magnet. Thus the piezoelectric cantilever is deflected and generates an output power. Experiment results show that the open circuit output voltage reaches 0.66V with respect to an alternative magnetic field produced by a 40-turn coil with 10mA AC current. The tested maximum output power is 0.4μW with optimal impedance of 500kOhms.
The need for manipulating matter at its smallest scale has been a hot topic in research for the last decades. As the final goal of arranging single atoms has been achieved, research focuses on two targets: firstly, improving the capabilities of existing technologies towards nanometer resolution and secondly, finding new methods for producing nanostructures in a fast and easy way. Here, we present a new maskless method for sub-micro-patterning of poly(methyl methacrylate) (PMMA) thin films. By applying atomic-force-microscope (AFM) assisted nano-xerography, electric charges were locally injected with an AFM-tip into PMMA. The resulting electrostatic patterns attracted charged gold-nanoparticles, which were selectively deposited onto the PMMA layers with lateral dimensions below 200 nm. In a second step, heat treatment at 275 °C initiated a selective decomposition of the PMMA layer, only observed in PMMA-areas covered with nanoparticles, whereas uncovered areas were not modified by the heat treatment. Analyzing the grooves with the AFM, we found that lines with a width in the sub-micrometer range to several micrometers have successfully been realized. We propose this new and promising method to manufacture nano-grooves used as masking for lift-off processes, for functionalization of underlying areas, or for micro-contact-printing.
Finite element method ( FEM) was used for the design of a piezoelectric rotary actuator by means of inchworm motion. This piezoelectric actuator can achieve large-stroke rotary with a high resolution. The common used cylinder rotor was replaced by one new designed rotor with a regular corrugated surface. The effect of the corrugated contact surface between the rotor and the stator was analyzed by finite element method. The contrastive simulations by the finite element method indicate that the stepping rotary angle can be improved by almost 4 times than the original one. This study will have some significance to the design and application of the inchworm type piezoelectric actuators.
Topographic and wetting properties of Ti-6Al-4V were modified by nanosecond laser irradiation. Three types of microstructures were created after the laser processing, the irradiated samples initially showed hydrophilic behavior, however, over time, these surfaces became hydrophobic with contact angles above 90°, and the maximum contact angle could reach 137°. The change from hydrophilicity to hydrophobicity was related to surface morphology, but it was not completely determined by surface morphology, because directly after laser treatment, the surface morphology was already formed and would not change by time. Through surface chemistry analysis, the explanation for the time dependency of the surface wettability was the modification of surface chemical composition, the increased carbon content on Ti-6Al-4V was proposed to be responsible for the hydrophobic behavior observed on the surface.
The paper describes an automated Particle Image Velocimetry (PIV) system designed for synchronised combined 2- and 3-component velocity measurements. The system has been designed to make measurements of velocity in the exhaust region of a scaled version of a gas turbine engine operating at high subsonic velocities and high temperatures (typically 800°C) for various configurations. For the PIV camera light detection the flow was seeded with 0.3μm aluminium oxide and 0.2-0.3μm oil mist particles. Tests were performed to determine optimum camera positions based upon Mie scatter calculations for the particles. An evaluation is presented discussing the design and accuracy of the system.
The special structural and mechanical characteristics of beetle elytral cuticle will be instructive in bionic for designing composites materials. Because the microscale or nanoscale thickness of the beetle cuticle, it was difficult to determine the cuticle's mechanical characteristics until nanoindentation techniques were developed. The nanomechanical characteristics ( reduced modulus Er and hardness H) of dung beetle Copris ochus Motschulsky cuticle were investigated by nanoindenter. To understand water's effect, samples were tested immediately or after different amounts of time. The nanoindentation results showed that the mechanical characteristics were strongly influenced by sample aging and that Er and H increased with a decrease in water content. The results were discussed in following about relationship of the mechanical characteristics of the cuticle and its behaviors.
Mesoporous anatase-brookite heterojunction TiO2 photocatalysts with tunable brookite/anatase ratios controlled by glycine assistant were successfully synthesized by facile hydrothermal process. In addition, pure brookite phase was prepared in the absence of glycine. The obtained TiO2 catalysts have been characterized by X-ray diffraction, Brunauer-Emmett-Teller analysis, transmission electron microscope and field emission-scanning electron microscopy. The X-ray diffraction revealed the formation of brookite-phase either in pure form in the absence of glycine or in mixing with anatase in the presence of glycine. The field emission-scanning electron microscopy micrograph of pure brookite indicated the formation of spindle-like structures with particle size ∼ 25 nm. The transmission electron microscope image of the optimum sample indicated the formation of small quasi-spherical particles and rod-like particles. N2 isotherm measurements confirmed that anatase/brookite TiO2 materials have mesoporous structure. The photocatalytic degradation of ibuprofen with low concentration was investigated using these novel TiO2 materials under UV irradiation light for water treatment. The anatase/brookite TiO2 samples showed a superior photocatalytic activity compared to pure brookite TiO2 sample. Sample containing 74.4% anatase/25.6 brookite displayed the highest photocatalytic activity for ibuprofen degradation (98.9 %) under UV light for 120 min due to the synergistic effect between anatase and brookite phases, high surface area (72.4 m2 g−1) and mesoporous structure.
This study presented a new way of extracting the altitude curves along the chromosomes by atomic force microscopy. Based on the correspondence between the altitude distribution from chromosomes surface and the band structure along the stained chromosomes, topography analysis of chromosomes using atomic force microscopy has the potential of karyotyping without complex chemical banding process. In the experiment, chromosomes prepared in air condition were imaged by atomic force microscopy and altitude curves extracted in conventional way and proposed way were compared to see the differences, which demonstrates that this new extracting method based on contour line has the advantage of taking the deformation caused by chromosomes contraction into consideration.
Nanowires (NWs), nano rods, nano whiskers are an important class of materials with the great potential for applied and fundamental basic research. The cross section of NWs is typically cylindrical, hexagonal, square, or triangular and is uniform with a high aspect ratio. Recently the new technology of 3D-nanomanipulation is proposed based on composite bimetallic structures with shape memory effect (SME). The present paper reports application of the new nano-tweezers system for experimental investigation of the individual nanowires of ZnxMg1-xO, which is the example of submicron-sized objects whose individual properties are difficult to study by standard methods. We describe the technology of preparation of ZnxMg1-xO NWs, the process of the selection of individual NWs by composite nano-tweezers with SME in vacuum chamber of FIB device and experimental study of their structure and morphology by TEM.
As cells are injected with micro-pipettes which operated by micro manipulator under powerful microscopes, the accuracy rate and success rate of micro-injection are determined by the pipette tip location and the depth down to the surface of petri dish. In this paper, the dynamic tip detection was realized by setting regions of interest in the images, handling the regions' images with Gaussian filter, binarizing the images with OTSU algorithm, selecting tip contour in the binarized images and traversaling all the points of the contour to get the most right point's coordinates. Then, lower the height in the Z direction with slow and uniform speed. The tip coordinates in the X direction were compared in time to judge whether the tip was down to the surface of petri dish. The location where the tip just contacted the dish surface was defined as the depth origin which the depth location was based on. The experiment results show that using the contour recognition method could obtain accurate tip location and depth location, and the success rate is more than 80%.
The piezo-driven technology with the aid of mercury is effective for performing the introcytoplamic sperm injection. However, the toxicity of mercury may cause damage to the operators and oocytes which call for the elimination of the mercury. Although the substitutes are developed, they don't work as well as the mercury. To obtain a better result without mercury, a piezo-driven technology based on the friction force is proposed for the piercing of mouse oocytes. A series of experiments are conducted which demonstrate the efficiency of this modified technology. Furthermore, the lateral vibration of the injection pipette is tiny as fine as 1μm which is physically invisible at 400 magnifications. This tiny lateral vibration contributes to the cellular piercing. According to the great cleavage rate of the mouse oocytes and gained tiny lateral vibration without the assistance of the mercury, this modified technology will have a tremendous potential in many fields.
Recently, new technology in 3D-nanomanipulation has been proposed based on the properties of Ni based functional alloys that exhibit thermoelastic martensitic transition and shape memory effects (SME) at micro and sub-micrometer dimensions. This report gives a survey of the current state of nanomanipulation and concludes that this new system can be applied to numerous problems, which require the manipulation and processing of nano and micro objects of different materials and structures. The report describes the application of the new technology of 3D-manipulation to the experimental study of individual CdSe nanowires, which are currently utilized in photovoltaic solar and hydrogen production renewable energy based applications.
There are many micro stomata and nanowires on the surface of Berberis thunbergii leaf (BTL). Water contact angle (CA) of fresh BTL is 150°, and rolling angle (RA) is above 10°, which shows good super-hydrophobic. In this paper, we introduce a simple method to fabricate super-hydrophobic surface using fresh BTL as template. CA of the as-prepared surface is 155°, and its corresponding RA is only 2°, demonstrating excellent super-hydrophobicity. Additionally, the as-prepared surface shows a certain extent of acid and alkali resistance, which superior to fresh BTL.
The biggest challenge of the practical applications of metamaterial-based perfect absorbers remains on the architectural design structure to engineer a system capable to achieve a near unity absorption, large absorption bandwidth and tunable resonance frequency and absorption strength. We propose and demonstrate an active visible and near-infrared metamaterial absorber formed by a sandwich of gold square metallic patch-vanadium dioxide thin film-gold layer. It shows a high absorptance up to 86% at the external temperature stimuli of 30°C, and about 30% at 85°C in the wide wavelength range from 0.9 μm to 1.5 μm. The proposed absorber has potential applications in active thermal control of electronic, optical and thermal devices.
Compared with the conventional flexure hinges, the motion range of superelastic flexure hinges can be significantly increased, due to the material's superelasticity effect. In this paper, the deformation of superelastic elliptic flexure hinges is investigated by using finite element method (FEM). The superelastic behavior of the material is described by a bilinear one-dimensional constitutive model based on the experimental data. A Bernoulli beam element considering the variation of cross section, and the geometry and material nonlinearities is presented by using co-rotational approach. Equilibrium equations of the structure are constructed by beam elements and solved by the Newton-Raphson iterative method. Numerical results show that the proposed method agrees well with the results calculated by ANSYS, and also reduces the element number and the computation cost greatly. The maximum rotation angles and rotation errors of flexure hinges are also investigated by the co-rotational beam element with the variety of notch length and minimum thickness.
A novel 6-DOF precision positioning system is designed in this paper, which is assembled by two type 3-DOF precision positioning stages. Each stage is driven by three piezoelectric actuators (PEAs), and guided by three symmetric T-shape hinges and three elliptical flexible hinges, respectively. The kinematics of this 6-DOF system are investigated. According to an effective kinematic model, the transformation matrix are obtained, which provides a useful tool to predict an output displacement. In addition, the dynamic model of the 6-DOF system is established. The PEAs can be treated as a force generator with a built-in spring-damper component. Furthermore, the characteristics of the 6-DOF system are evaluated in this paper by the FEM simulation. The design structure provides the high dynamic bandwidth. Meanwhile, the experiment is performed to verify the 6-DOF stage has a good characteristic.
This paper presents the identification of a novel micro-positioning stage driven by voice coil motors (VCM) with hysteresis phenomenon, which is described by Bouc-Wen model. Real-coded genetic algorithm (RGA) method with adaptive crossover and mutation is implemented to identify the parameters simultaneously. In comparison of the experiment and simulations results, it can be found that the adopting Bouc-Wen model to the positioning system is feasible and the method utilized in this paper ensures the simulation results in good agreement with experiment.
