Micromechanical Components Research Articles

ШЛЯХИ КОМПЛЕСНОГО ЗАБЕЗПЕЧЕННЯ ТОЧНОСТІ ТА ЗАВАДОЗАХИЩЕНОСТІ РАДІОЛОКАЦІЙНИХ СИСТЕМ АВТОНОМНОЇ НАВІГАЦІЇ ТА ПОПЕРЕДЖЕННЯ ЗІТКНЕНЬ НАЗЕМНИИХ РУХОМИХ ОБ’ЄКТІВ

Modern navigation equipment should make it possible to determine in real-time the location of a ground-moving object (NRA) and the direction of its movement. To solve such problems, the equipment of consumers (AS) of satellite radio navigation systems (SRNS) is widely used. However, a number of circumstances, such as traffic in tunnels, and forests, within dense urban areas, the presence of natural and man-made radio interference, do not provide continuous reception of information from the necessary grouping of navigation Satellites. Therefore, for continuous navigation, NRAs are supplemented with autonomous navigation tools. In recent times, inertial means of autonomous navigation have been widely developed. The introduction of MEMS technologies and devices that combine microelectronic and micromechanical components has made it possible to create a wide range of small-sized sensors, such as accelerometers, angular velocity sensors, gyroscopes, and magnetometric sensors. The development of microwave technologies has made it possible to create small-sized radar sensors, which determine the further development of odometric navigation tools. Radar sensors play a special role in collision avoidance systems for NRA movement in columns and in conditions of limited optical visibility. Creating autonomous navigation systems based on such sensors is an urgent scientific and technical task. Radar meters based on the Doppler effect are all-weather and round-the-clock tools for a comprehensive system technical solution to this problem. The Doppler sensitivity of the meters significantly depends on the frequency of operation of the receiving and transmitting equipment, the maximum of which is reached in the millimeter frequency range. Taking into account the circumstances mentioned above, as well as the relatively high price of radar equipment, an important scientific and practical problem is the maximum unification of technical solutions for the construction of meters, namely: the choice of circuitry, element base and materials; development of test methodology, composition of spare tools and devices, operational documentation. An analysis of the tasks solved by radar meters of NRA motion parameters for their autonomous navigation and for ensuring traffic safety in columns and on rough terrain, namely, the prevention of collision with obstacles in conditions of limited optical visibility, was carried out. Radar methods of autonomous navigation and collision avoidance are analyzed, their disadvantages and advantages are indicated, proposals for solving the issues of improving the accuracy and noise immunity of radar meters are formed.

Localized Induction Heating of Cu-Sn Layers for Rapid Solid-Liquid Interdiffusion Bonding Based on Miniaturized Coils.

Considering the demand for low temperature bonding in 3D integration and packaging of microelectronic or micromechanical components, this paper presents the development and application of an innovative inductive heating system using micro coils for rapid Cu-Sn solid-liquid interdiffusion (SLID) bonding at chip-level. The design and optimization of the micro coil as well as the analysis of the heating process were carried out by means of finite element method (FEM). The micro coil is a composite material of an aluminum nitride (AlN) carrier substrate and embedded metallic coil conductors. The conductive coil geometry is generated by electroplating of 500 µm thick copper into the AlN carrier. By using the aforementioned micro coil for inductive Cu-Sn SLID bonding, a complete transformation into the thermodynamic stable ε-phase Cu3Sn with an average shear strength of 45.1 N/mm2 could be achieved in 130 s by applying a bond pressure of 3 MPa. In comparison to conventional bonding methods using conduction-based global heating, the presented inductive bonding approach is characterized by combining very high heating rates of about 180 K/s as well as localized heating and efficient cooling of the bond structures. In future, the technology will open new opportunities in the field of wafer-level bonding.

A passive acceleration sensor with mechanical 6 bit memory and mechanical analog-to-digital converter

This paper presents the design, modeling, fabrication and characterization of a passive micromechanical acceleration sensor intended for condition monitoring. The sensor is composed of purely micromechanical components forming a mechanical integrated sensing circuit, which allows to measure, select, store, and digitize the peak value of an imposed acceleration without the need of electrical auxiliary energy. We present micromechanical components arranged in a mechanical integrated sensor circuit. A network model is derived describing the static mechanical properties of the system. As part of the accelerometer, a cascaded mechanical memory is presented in detail which allows to store an acceleration peak value with a resolution of 6 bits, i.e. 64 discrete states. The memory is resettable by an electrostatic actuator. For an electrical read out of the memory, e.g. by RFID, an integrated micromechanical analog-to-digital converter is used.

Micro-friction stir welding (μFSW) – A review

Micro-friction stir welding (μFSW) is a revolutionary joining process which is usually used for the welding of metallic alloys, like aluminium, magnesium, copper, lead, zinc, titanium and other softer structural alloys. Micro-friction stir welding is employed to join thin electrical components and micro-mechanical components which is primarily used in industries like; aerospace, automotive and other industrial applications. Tool rotational speed along with speed of welding and angle of tool tilting are most vital parameters for the μFSW process which affects the joint property. It gives better joint properties than the base material properties.

Additive-Manufactured Organic Interposers

Abstract The trend toward heterogeneous integration of optoelectronic, electronic, and micromechanical components favors three-dimensional (3D) integration in which the components are not arranged side-by-side but rather in vertical stacks. This presents a particular challenge due to the fact that the stacked components have different geometric dimensions, and their contact surfaces are also dissimilar. Therefore, an intermediate substrate, the so-called interposer, with different formats (i.e., flip-chip, wire-bond, and hybrid flip-chip/wire bond) comes into play. Currently, the interposers are mainly made of silicon or glass, which incur huge additional costs to the packaged components. In this study, the unique advantages of additive manufacturing (AM) are exploited to realize organic interposers. The proposed interposers provide easy signal probing and flexible die-to-board integration in lower costs without any lithography process, drilling, plating, or any waste. Accordingly, the two state-of-the-art 3D printers (i.e., a monomaterial 3D printer and a bimaterial 3D printer) were utilized for the manufacturing of the interposer parts. The complementary circuitry for vias and through-holes was facilitated by also additive technologies, i.e., 2D-inkjet printing and microdispensing. Moreover, and to manifest the unique possibilities within AM for the next generation of interposers, two examples for 3D-printed interposers with incorporated added-features, i.e., pillars for flip-chip bonding and cavities for face-up die-attachment were realized. The assemblies were consequently assessed by electrical examinations. Conclusively, the main opportunities and challenges toward the full implementation of AM technology for the fabrication of organic interposers with added-features such as integrated multipurpose vias were discussed. Based on the results obtained from this study, it was found that bimaterial 3D printer was more efficient and powerful for the construction of interposers.

Precision micro-mechanical components in single crystal diamond by deep reactive ion etching

The outstanding material properties of single crystal diamond have been at the origin of the long-standing interest in its exploitation for engineering of high-performance micro- and nanosystems. In particular, the extreme mechanical hardness, the highest elastic modulus of any bulk material, low density, and the promise for low friction have spurred interest most notably for micro-mechanical and MEMS applications. While reactive ion etching of diamond has been reported previously, precision structuring of freestanding micro-mechanical components in single crystal diamond by deep reactive ion etching has hitherto remained elusive, related to limitations in the etch processes, such as the need of thick hard masks, micromasking effects, and limited etch rates. In this work, we report on an optimized reactive ion etching process of single crystal diamond overcoming several of these shortcomings at the same time, and present a robust and reliable method to produce fully released micro-mechanical components in single crystal diamond. Using an optimized Al/SiO2 hard mask and a high-intensity oxygen plasma etch process, we obtain etch rates exceeding 30 µm/h and hard mask selectivity better than 1:50. We demonstrate fully freestanding micro-mechanical components for mechanical watches made of pure single crystal diamond. The components with a thickness of 150 µm are defined by lithography and deep reactive ion etching, and exhibit sidewall angles of 82°–93° with surface roughness better than 200 nm rms, demonstrating the potential of this powerful technique for precision microstructuring of single crystal diamond.

Design of interfaces with lithographically patterned adhesive pads for gluing at the microscale

The creation of small adhesive pads by traditional dispensing methods is technically limited. However, the miniaturisation of micromechanical components requires the parallel development of adhesive pads with sizes in the sub-50 µm range combining good geometrical confinement and mechanical strength. Therefore, a new design of interfaces with adhesive pads of 32–8 µm are presented through local deposition of a liquid adhesive by means of “top-down” or “bottom-up” patterning. Using lithography and photochemical process, the shape of the adhesive pads is first stabilized by partial cross-linking and effective adhesive bonding with a counterface subsequently takes place during full cross-linking. The parameters for photochemical cross-linking of the adhesive pads are optimised and the mechanical performance of the patterned adhesive interfaces is evaluated. For “top-down” patterned adhesive interfaces, the geometrical stabilisation of the adhesive pads requires relatively long cross-linking times consequently resulting in low mechanical strength. For “bottom-up” patterned adhesive interfaces, the formation of adhesive pads is controlled by self-organisation of the adhesive over chemically structured substrates and requires short cross-linking times for geometrical stabilization, leading to higher mechanical strength during adhesive bonding. The fabrication of adhesive pads by a “bottom-up” approach is further discussed in relation to the influences of processing parameters on dewetting of the adhesive.

Effect of pressure on nonlinear dynamics and instability of electrically actuated circular micro-plates

Characterization of nonlinear behavior of micro-mechanical components in MEMS applications plays an important role in their design process. In this paper, nonlinear dynamics, stability and pull-in mechanisms of an electrically actuated circular micro-plate subjected to a differential pressure are studied. For this purpose, a reduced-order model based on an energy approach is formulated. It has been shown that nonlinear dynamics of an electrically actuated micro-plate, in the presence of differential pressure, significantly differs from those under purely electrostatic loads. The micro-plate may lose stability upon either saddle-node or period-doubling bifurcations. It has also been found that in the presence of a differential pressure, increasing the DC or AC voltages may surprisingly help to stabilize the motion of the micro-plate.

New Approach to Increase CNT Contents in Electrodeposited Ni-CNT Composite Thin Films by Modified Current Conditions

In this paper, an electrodeposition method for nickel (Ni)-multiwalled carbon nanotubes (MWCNTs) composite thin films is presented. The composite film is deposited using an electrolyte in which MWCNTs are randomly dispersed. Two kinds of MWCNTs annealed at 1200 °C and 2600 °C were used for the electrodeposition using pulse or sine waveforms. An electrodeposition condition using CNT annealed at 1200 °C and sine waveform with maximum current 0.2 A and frequency 5.0 Hz results in a maximum CNT weight fraction of 5.4% in the composite film. The electrodeposited film with the maximum CNT content shows a microindentation hardness of 17.0 GPa, which is approximately 1.45 times greater than that of a pure Ni film. Moreover, mechanical strengthening is found in the composite films due to the addition of CNTs. This result shows that the electrodeposition for the Ni-MWCNT composite thin film with modified current condition would be applicable to microsystem, which requires micromechanical components with high mechanical strength.

Electrodeposition of dilute Ni-W alloy with enhanced thermal stability: Accessing nanotwinned to nanocrystalline microstructures

We report on the effects of W content on the microstructure, mechanical properties and thermal stability of dilute NiW electrodeposits − up to 5at% W. The microstructure of NiW is significantly affected by W content. Pure Ni films were nanocrystalline (nc), whereas NiW films with 0.5at% W showed a bimodal microstructure consisting of nanotwinned (nt) fiber-like micrometer-grains and nc-grains. Further microstructural change was observed at 4at% W and more; the growth of nt-grains was largely suppressed and nc-grains were uniformly distributed in the film. This microstructural transition with W content can be explained by two distinct and competing effects of W: the reduction of stacking fault energy and the grain growth restriction. Nc-NiW shows an enhanced hardness compared with those of nc-Ni and nt-NiW, due to the grain refinement effect of W. Moreover, it shows a grain-boundary stability significantly superior to nc-Ni, suggesting potential improvement in the time-dependent deformation properties. Because a dilute Ni-W alloy can be electrodeposited with a relatively low stress, which is essential for thick-film applications, such an alloy will be a promising alternative of nc-Ni for applications to micromechanical components where thick films with better thermal stability and creep resistance are required.

Микромеханические компоненты микроробототехнических устройств космического назначения

Микромеханические компоненты микроробототехнических устройств космического назначения

Local characterisation of variances for the planning and configuration of process chains in micro manufacturing

During the last decades, a continuous trend towards miniaturisation leads to an increasing demand of metallic micromechanical components. To achieve an economic production on an industrial scale, the planning and configuration of process chains has become a key success factor. Thereby, the occurrence of so-called size-effects renders the planning and particularly the configuration of process chains complicated. While process planners have to ensure very small tolerances, these size-effects lead to comparably strong variances within the behaviour of processes. To cope with these, this article proposes an extension to the μ-ProPlAn methodology. While μ-ProPlAn, in its current state, provides tools to characterise and utilise interdependencies between production relevant parameters, it lacks the capabilities to quantify and use variances for the prediction of process results. In this article, we propose an extension to this methodology, enabling a local estimation of variance of relevant process parameters using sample data. As a result, the planning quality can be increased as additional goals and methods for optimisation become available.

Three-Dimensional Printing of Photoresponsive Biomaterials for Control of Bacterial Microenvironments.

Advances in microscopic three-dimensional (μ3D) printing provide a means to microfabricate an almost limitless range of arbitrary geometries, offering new opportunities to rapidly prototype complex architectures for microfluidic and cellular applications. Such 3D lithographic capabilities present a tantalizing prospect for engineering micromechanical components, for example, pumps and valves, for cellular environments composed of smart materials whose size, shape, permeability, stiffness, and other attributes might be modified in real time to precisely manipulate ultralow-volume samples. Unfortunately, most materials produced using μ3D printing are synthetic polymers that are inert to biologically tolerated chemical and light-based triggers and provide low compatibility as materials for cell culture and encapsulation applications. We previously demonstrated feasibility for μ3D printing environmentally sensitive, microstructured protein hydrogels that undergo volume changes in response to pH, ionic strength, and thermal triggers, cues that may be incompatible with sensitive chemical and biological systems. Here, we report the systematic investigation of photoillumination as a minimally invasive and remotely applied means to trigger morphological change in protein-based μ3D-printed smart materials. Detailed knowledge of material responsiveness is exploited to develop individually addressable "smart" valves that can be used to capture, "farm", and then dilute motile bacteria at specified times in multichamber picoliter edifices, capabilities that offer new opportunities for studying cell-cell interactions in ultralow-volume environments.

Experimental validation and effect of modelling assumptions in the hierarchical multi-scale simulation of the cup drawing of AA6016 sheets

An essential step in the improvement of design strategies for a wide range of industrial deep drawing applications is the development of methods which allow for the precise prediction of shape and processing parameters. Earlier work has demonstrated, in a clear but qualitative manner, the capabilities of the hierarchical multiscale (HMS) model, which predicts the anisotropic plastic properties of metallic materials based on a statistical analysis of microstructure-based anisotropy and a continuous description of the yield locus. The method is implemented into the ABAQUS finite-element software but, until recently, little attention had been paid to other factors which determine the accuracy of a finite element prediction in general, such as mesh size, friction coefficient and rigid/elastic modelling of the tools. Through the analysis of cup drawing, which is a well-established laboratory-scale test relevant to industrial applications, a quantitative comparison is provided between measured cup geometry and punch force and modelling results for commercial AA6016T4 aluminium sheets. The relatively weak earing behaviour of these materials serves to emphasise the small differences still found between model and experiment, which may be addressed by future refinement of the micromechanical component of the HMS. Average cup height and punch force, which is an important process parameter omitted in earlier studies, depend primarily on the friction coefficient and assumptions in the modelling of the tools. Considering the balance between accuracy and precision, it is concluded that the proposed methodology has matured sufficiently to be used as a design tool at industrial level.

A micromechanical device that monitors arterial pressure during general anesthesia and in intensive care units

A vibroacoustic fiber optic system that consists of micromechanical components designated for use in medicine and biology is reviewed. A theoretical analysis of a fiber optic microphone is done and its optimal construction parameters are determined. The possibility of using the developed system with magnetic resonance tomography to noninvasively measure man's arterial pressure is specified.

The capillary adhesion technique: a versatile method for determining the liquid adhesion force and sample stiffness.

We report a novel, practical technique for the concerted, simultaneous determination of both the adhesion force of a small structure or structural unit (e.g., an individual filament, hair, micromechanical component or microsensor) to a liquid and its elastic properties. The method involves the creation and development of a liquid meniscus upon touching a liquid surface with the structure, and the subsequent disruption of this liquid meniscus upon removal. The evaluation of the meniscus shape immediately before snap-off of the meniscus allows the quantitative determination of the liquid adhesion force. Concurrently, by measuring and evaluating the deformation of the structure under investigation, its elastic properties can be determined. The sensitivity of the method is remarkably high, practically limited by the resolution of the camera capturing the process. Adhesion forces down to 10 µN and spring constants up to 2 N/m were measured. Three exemplary applications of this method are demonstrated: (1) determination of the water adhesion force and the elasticity of individual hairs (trichomes) of the floating fern Salvinia molesta. (2) The investigation of human head hairs both with and without functional surface coatings (a topic of high relevance in the field of hair cosmetics) was performed. The method also resulted in the measurement of an elastic modulus (Young’s modulus) for individual hairs of 3.0 × 105 N/cm2, which is within the typical range known for human hair. (3) Finally, the accuracy and validity of the capillary adhesion technique was proven by examining calibrated atomic force microscopy cantilevers, reproducing the spring constants calibrated using other methods.

Length effect on creep of silicon cantilever microbeams

Creep behavior is very important to reliability of micromechanical components. Therefore, there are some emerging research efforts that focus on creep of silicon. However, few have focused on interaction among microscale dimension effect, temperature, and applied stress, which are more crucial to microelectrical mechanical system components compared with regular size components. This paper presents investigation of creep of single crystal silicon cantilever microbeams with a specific focus on the length effect. Results are presented characterizing the creep behavior in the length range of 300–700 µm, the temperature range of 600–700℃, and the stress range of 235–501 MPa. As the temperature or stress increases, the creep rate of silicon increases and duration of the steady-state creep decreases. Creep rate decreases with the increase of microbeam length. At 600℃, creep rupture lifetime approximately increases with the increase of microbeam length. At 700℃, maximum lifetime shifts to medium length of 400 µm. Factors that influence rupture lifetime include short beam effect, defect distribution, stress, temperature, and brittleness caused by oxidation. To summarize, creep failure modes for short beam and long beam are, respectively, dislocation motion by multiple slip systems and single slip system.

New Opportunities for Polymer Nanocomposites in Microfluidics and Biomedical MEMS: An introduction to cutting-edge composite polymer materials for use in microfluidics and biomedical MEMS

From the miniaturization of laboratory instrumentation for bedside rapid diagnosis of disease to bioanalytical instrumentation for studying individual cells or molecules in new ways using micromachined structures, microfluidics is well established as an exciting area of research with great promise and an ever-growing application base. Microfluidics is revolutionizing laboratory methods and biomedical devices, offering new capabilities and instrumentation for multiple areas such as deoxyribonucleic acid (DNA) analysis, proteomics, enzymatic analysis, single-cell analysis, immunology, point-of-care medicine, personalized medicine, drug delivery, and environmental toxin and pathogen detection. Through the combination of biosensors; microchannel fluid transport; and other micromechanical, optical, chemical, and fluidic components; microfluidic-based instrumentation has spawned research into miniaturized systems, e.g., bedside rapid diagnosis, wearable environmental monitoring, and biological single-cell monitoring.

The Downsizing Effects in EDM Drilling of Micro Holes

The recent miniaturization trend in manufacturing, has enhanced the production of new and highly sophisticated systems in various industrial fields. In recent years, machining of the so called difficult to cut materials has become an important issue in several sectors. Micro Electrical Discharge Machining (micro-EDM) thanks to its contactless nature, is one of the most important technologies for the machining of this type of materials and it can be considered as one of the most promising manufacturing technologies for the fabrication of micro components. One of the most relevant applications of micro-EDM is micro-drilling. Micro holes in fact, are widely used for example in micro-electromechanical systems (MEMS), serving as channels or nozzles to connect two micro-features, and in micro-mechanical components. The present study is about micro drilling of metal plates by means of micro-EDM technology. In particular, the aim of this work is to investigate the effects of the downsizing of the micro holes diameter on the drilling performances. The influence of the reduction of the diameters in terms of both process performances (e.g., tool wear, taper rate, diametrical overcut) and general quality of the holes was investigated. Steel plates having thickness equal to 0.8 mm were taken into account. The drilling process was carried out using a micro-EDM machine Sarix SX 200 with carbide electrodes having diameter equal to 300, 200, 100 and 50 μm. Since the standard electrodes adopted in this study had a diameter equal to 300 μm, a wire EDM unit was used to obtain the other electrodes. The relationship between the process parameters considered the most significant and the final output, was studied. Furthermore, the geometrical and dimensional properties of the micro-holes were analyzed using both optical and scanning electron microscopes. In particular, it is demonstrated that the diameter size has a significant influence on the final value of the diametrical overcut while peak current and frequency parameters have a negligible effect.

Micro-fabrication of air-bearing grooves onto inner surfaces of fine copper pipes

Applicability of laser-scan lithography onto inner surfaces of small-diameter pipes was investigated by fabricating fine air-bearing grooves. Herring bone patterns with a mean width of [email protected] were precisely formed on inner surfaces of copper pipes with an inner diameter of 2mm using laser direct writing lithography and sequent electrolytic etching. The pipe was cut and machined to a bearing bushing, and a rotor with the air-bearing bushing was fabricated. An aluminum hollow shaft was inserted in it, and the rotor was supported by the air bearing and magnetic thrust bearings placed at the both sides. As a result, the rotor was rotated very smoothly with a high-speed of more than 20,000rpm by blowing air to the rotor. Using conventional machining technology, it is difficult to form precise herring-bone shape grooves onto inner surfaces of such fine pipes. It was demonstrated that the combination of inside lithography and electrolytic etching was very useful for fabricating micro-mechanical components requiring precise patterning on their inside surfaces.