Assembly Of Microcomponents Research Articles

Development and analysis of computer vision system for micromechanics

Summary: In micromechanics the best technologies are MicroElectroMechanical Systems (MEMS) and MicroEquipment Technology (MET). The MEMS used the electronic technology to produce mechanical components. Due to the advantages of the MET such as the development of low-cost micro devices, the possibility of using various manufacturing materials, the possibility of producing three-dimensional microcomponents it will be very useful to automatize all processes of mechanics production and develop different technological innovations. The automation and robotics are two closely related technologies since automation can be defined as a technology that is related to the use of mechanical-electrical systems based on computers for the operation and control of production. The field of micromechanics has been involved in different applications that cover almost all areas of science and technology, an example of this is the management of microdevices for the autofocus of digital cameras whose objective is image processing (recognizing and locate objects). The use of computer vision systems can help to automate the work of MEMS and MET systems, so the study of image processing using a computer is very important. The objective was to design a computer vision system that allows the movement of the lens to focus the work area, for the monitoring of the micromachine tool in manufacturing processes and assembly of microcomponents in real time using previously developed image recognition algorithms. The developed algorithms use the criterion of improving the contrast of the input image. We describe our approach and obtained results. This approach can be used not only in micromechanics but in nanomechanics too

Optimization parameter for microgripper based on triple-stair compliant mechanism using GTs-TOPSIS

In manipulating the assembly of micro-components, the symmetrical microgripper mechanism often causes destruction, damaging those components during manipulation, due to the phenomenon of non-uniform clamping force output from the clamp. From this disadvantage, a new asymmetric microgripper structure is proposed with stable output clamping force. The asymmetric microgripper structure will have a smaller output displacement than that of the symmetric structure. Therefore, to increase the output displacement gain, a flexible hinge with a triple-stair half-bridge-style mechanism (TSBM) is adopted to design the amplifier of the asymmetrical microgripper. The finite element method is applied to analyze the displacement and stress. The optimization process is performed based on the geometric parametric properties of the structure. Using the technology for order preference by similarity to ideal solution (TOPSIS) based on the Grey relationship analysis (GRA), we obtained the maximum displacement output and minimum stress. Results show that the maximum output displacement is 5,818 mm, and stress after analysis is 2,432 MPa. The test is conducted to verify the optimal results and the effectiveness of the optimization method. Finally, experimental experiments were performed, with a 4.8% difference from the FEA results. The results from the experimental test verify that the microgripper’s maximum displacement amplification ratio is approximately 58.2 times.

Simulation of metal microcomponents picking up by electrochemical based on ABAQUS

The development of micromanipulation technology has an important impact on the research in the microfield, which mainly focuses on the preparation and assembly of microcomponents, in which the microcomponent picking technology is used. The existing picking methods mainly use manipulation tools to clamp or adsorb components, which may destroy or fail to pick objects in the process of manipulation, and the efficiency is relatively low. In order to solve the problems in the existing manipulation methods, a new metal microcomponent picking method based on electrochemistry is proposed, which mainly uses the electrochemical principle to produce metal deposition, connect the manipulation tool and the object, and indirectly control the object by moving the manipulation tool. In this paper, the simulation software ABAQUS is used to pick up the microcopper wires with the length of 100, 200 and 300 [Formula: see text]m by using a pipette with a nozzle diameter of 15 [Formula: see text]m. The force curve between the tool and the object during the manipulation process is obtained. The feasibility of the method is verified by theoretical analysis and simulation experiments.

Development of new sticky and conducting polymer surfaces for MEMS applications

The development of new surfaces, highly sticky and conducting, is a great challenge in the field of microdevices fabrication, and more precisely for the 3D assembly of microcomponents. Such surfaces were prepared by electrochemical deposition of polyaniline films. The films prepared from a phosphoric acid solution were more adhesive than the ones obtained in other acids. Indeed, the adhesion of the polyaniline films prepared in H3PO4 was found to be high (> 1 µN) and stable in time, as shown by AFM force measurements. The adhesion properties were correlated with the morphology, thickness and roughness of the polyaniline films, and the electrodeposition conditions (H3PO4 concentration and electrodeposition time) were optimized. The adhesion properties of this original polymer films were found to be similar to those of the best commercial glues. The conductivity of the polyaniline film was also demonstrated as well as the possibility for the polyaniline films to switch reversibly from a non-adhesive to an adhesive behavior. A wide range of applications, in the field of telecommunications, bioengineering, and more generally speaking MEMS (microelectromechanical systems) can be envisaged for these materials.

Evaluation of macro sized metal based microgrippers for handling microcomponents

This work presents evaluation of macro sized metal based microgrippers of various shapes such as circular, square and rectangular, which can hold circular, square and rectangular microcomponents respectively. The developed microgrippers can be used effectively as a holding device in mechanical environments and also in the assembly of microcomponents. Microgrippers are designed and analyzed using SOLIDWORKS and COMSOL Multiphysics respectively. Fabrication of microgrippers are carried out using direct metal laser sintering process with six gripping arms to prevent the slipping of the microcomponents during handling. The microgrippers were actuated by means of specially designed actuation system. The fabricated microgrippers are characterized for gripping displacements and gripping forces and the results are compared with that of the simulation and analytical results. It is observed that the displacements of the gripping arms of the fabricated microgrippers are four times higher than that of the input displacements of the actuator. This is found to be in the higher order than that of reported in the literature. Further, the circular based microgrippers were tested in micro-drilling and micro-welding as micro-chuck and micro-electrode holder respectively and they are found to be working satisfactorily.

Optical screw-wrench for microassembly

For future micro- and nanotechnologies, the manufacturing of miniaturized, functionalized, and integrated devices is indispensable. In this paper, an assembly technique based on a bottom-up strategy that enables the manufacturing of complex microsystems using only optical methods is presented. A screw connection is transferred to the micrometer range and used to assemble screw- and nut-shaped microcomponents. Micro-stereolithography is performed by means of two-photon polymerization, and microstructures are fabricated and subsequently trapped, moved, and screwed together using optical forces in a holographic optical tweezer set-up. The design and construction of interlocking microcomponents and the verification of a stable and releasable joint form the main focus of this paper. The assembly technique is also applied to a microfluidic system to enable the pumping or intermixing of fluids on a microfluidic chip. This strategy not only enables the assembly of microcomponents but also the combination of different materials and features to form complex hybrid microsystems.

Influence of mechanical noise inside a scanning electron microscope.

The scanning electron microscope is becoming a popular tool to perform tasks that require positioning, manipulation, characterization, and assembly of micro-components. However, some of these applications require a higher level of performance with respect to dynamics and precision of positioning. One limiting factor is the presence of unidentified noises and disturbances. This work aims to study the influence of mechanical disturbances generated by the environment and by the microscope, identifying how these can affect elements in the vacuum chamber. To achieve this objective, a dedicated setup, including a high-resolution vibrometer, was built inside the microscope. This work led to the identification and quantification of main disturbances and noise sources acting on a scanning electron microscope. Furthermore, the effects of external acoustic excitations were analysed. Potential applications of these results include noise compensation and real-time control for high accuracy tasks.

Guided and magnetic self-assembly of tunable magnetoceptive gels.

Self-assembly of components into complex functional patterns at microscale is common in nature, and used increasingly in numerous disciplines such as optoelectronics, microfabrication, sensors, tissue engineering and computation. Here, we describe the use of stable radicals to guide the self-assembly of magnetically tunable gels, which we call ‘magnetoceptive’ materials at the scale of hundreds of microns to a millimeter, each can be programmed by shape and composition, into heterogeneous complex structures. Using paramagnetism of free radicals as a driving mechanism, complex heterogeneous structures are built in the magnetic field generated by permanent magnets. The overall magnetic signature of final structure is erased via an antioxidant vitamin E, subsequent to guided self-assembly. We demonstrate unique capabilities of radicals and antioxidants in fabrication of soft systems with heterogeneity in material properties, such as porosity, elastic modulus and mass density; then in bottom-up tissue engineering and finally, levitational and selective assembly of microcomponents.

Design of a planar 3-DOF parallel micromanipulator

A planar three degree-of-freedom (DOF) parallel manipulator is proposed to be applied for alignment during assembly of microcomponents. It adopts a PRR (prismatic-revolute-revolute) mechanism to meet the requirements of high precision for assembly and robustness against disturbance. The mechanism was designed to have a large workspace and good dexterity because parallel mechanisms usually have a narrow range and singularity of motion compared to serial mechanisms. Inverse kinematics and a simple closed-loop algorithm of the parallel manipulator are presented to control it. Experimental tests have been carried out with high-resolution capacitance sensors to verify the performance of the mechanism. The results of experiments show that the manipulator has a large workspace of ±1.0 mm, ±1.0 mm, and ±10 mrad in the X-, Y-, and θ-directions, respectively. This is a large workspace when considering it adopts a parallel mechanism and has a small size, 100 × 100 × 100 mm3. It also has a good precision of 2 μm, 3 μm, and 0.2 mrad, in the X-, Y-, and θ-axes, respectively. These are high resolutions considering the manipulator adopts conventional joints. The manipulator is expected to have good dexterity.

Electrokinetic and optical control of bacterial microrobots

One of the great challenges in microscale science and engineering is the independent manipulation of cells and man-made objects on the micron scale. For such work, motile microorganisms are integrated with engineered systems to construct microbiorobots (MBRs). MBRs are negative photosensitive epoxy (SU-8) microfabricated structures with typical feature sizes ranging from 1 to 100 µm coated with a monolayer of swarmer cells of the bacterium Serratia marcescens. The adherent cells naturally coordinate to propel the microstructures in fluidic environments. In this study, ultraviolet light is used to control rotational motion and direct current electric fields are used to control the two-dimensional movement of MBRs. They are steered in a fully automated fashion using computer-controlled visual servoing, used to transport and manipulate micron-sized objects, and employed as cell-based biosensors. This work is a step toward in vitro mechanical or chemical manipulation of cells as well as controlled assembly of microcomponents.

Flexible pneumatic micro-actuators: analysis and production

Compliant pneumatic micro-actuators are interesting for applications requiring large strokes and forces in delicate environments. These include for instance minimally invasive surgery and assembly of microcomponents. This paper presents a theoretical and experimental analysis of a balloon-type compliant micro-actuator. Finite element modeling is used to describe the complex behavior of these actuators, which is validated through prototype experiments. Prototypes with dimensions ranging from 11mm x 2mm x 0.24mm to 4mm x 1mm x 0.12mm are fabricated by a newly developed production process based on micromilling and micromolding. The larger actuators are capable of delivering out-of-plane strokes of up to 7mm. Further, they have been integrated in a platform with two rotational and one translational degree of freedom.

Publisher’s Note: “Review Article—Dielectrophoresis: Status of the theory, technology, and applications” [Biomicrofluidics 4, 022811 (2010)

A review is presented of the present status of the theory, the developed technology and the current applications of dielectrophoresis (DEP). Over the past 10 years around 2000 publications have addressed these three aspects, and current trends suggest that the theory and technology have matured sufficiently for most effort to now be directed towards applying DEP to unmet needs in such areas as biosensors, cell therapeutics, drug discovery, medical diagnostics, microfluidics, nanoassembly, and particle filtration. The dipole approximation to describe the DEP force acting on a particle subjected to a nonuniform electric field has evolved to include multipole contributions, the perturbing effects arising from interactions with other cells and boundary surfaces, and the influence of electrical double-layer polarizations that must be considered for nanoparticles. Theoretical modelling of the electric field gradients generated by different electrode designs has also reached an advanced state. Advances in the technology include the development of sophisticated electrode designs, along with the introduction of new materials (e.g., silicone polymers, dry film resist) and methods for fabricating the electrodes and microfluidics of DEP devices (photo and electron beam lithography, laser ablation, thin film techniques, CMOS technology). Around three-quarters of the 300 or so scientific publications now being published each year on DEP are directed towards practical applications, and this is matched with an increasing number of patent applications. A summary of the US patents granted since January 2005 is given, along with an outline of the small number of perceived industrial applications (e.g., mineral separation, micropolishing, manipulation and dispensing of fluid droplets, manipulation and assembly of micro components). The technology has also advanced sufficiently for DEP to be used as a tool to manipulate nanoparticles (e.g., carbon nanotubes, nano wires, gold and metal oxide nanoparticles) for the fabrication of devices and sensors. Most efforts are now being directed towards biomedical applications, such as the spatial manipulation and selective separation/enrichment of target cells or bacteria, high-throughput molecular screening, biosensors, immunoassays, and the artificial engineering of three-dimensional cell constructs. DEP is able to manipulate and sort cells without the need for biochemical labels or other bioengineered tags, and without contact to any surfaces. This opens up potentially important applications of DEP as a tool to address an unmet need in stem cell research and therapy.

Review article-dielectrophoresis: status of the theory, technology, and applications.

A review is presented of the present status of the theory, the developed technology and the current applications of dielectrophoresis (DEP). Over the past 10 years around 2000 publications have addressed these three aspects, and current trends suggest that the theory and technology have matured sufficiently for most effort to now be directed towards applying DEP to unmet needs in such areas as biosensors, cell therapeutics, drug discovery, medical diagnostics, microfluidics, nanoassembly, and particle filtration. The dipole approximation to describe the DEP force acting on a particle subjected to a nonuniform electric field has evolved to include multipole contributions, the perturbing effects arising from interactions with other cells and boundary surfaces, and the influence of electrical double-layer polarizations that must be considered for nanoparticles. Theoretical modelling of the electric field gradients generated by different electrode designs has also reached an advanced state. Advances in the technology include the development of sophisticated electrode designs, along with the introduction of new materials (e.g., silicone polymers, dry film resist) and methods for fabricating the electrodes and microfluidics of DEP devices (photo and electron beam lithography, laser ablation, thin film techniques, CMOS technology). Around three-quarters of the 300 or so scientific publications now being published each year on DEP are directed towards practical applications, and this is matched with an increasing number of patent applications. A summary of the US patents granted since January 2005 is given, along with an outline of the small number of perceived industrial applications (e.g., mineral separation, micropolishing, manipulation and dispensing of fluid droplets, manipulation and assembly of micro components). The technology has also advanced sufficiently for DEP to be used as a tool to manipulate nanoparticles (e.g., carbon nanotubes, nano wires, gold and metal oxide nanoparticles) for the fabrication of devices and sensors. Most efforts are now being directed towards biomedical applications, such as the spatial manipulation and selective separationenrichment of target cells or bacteria, high-throughput molecular screening, biosensors, immunoassays, and the artificial engineering of three-dimensional cell constructs. DEP is able to manipulate and sort cells without the need for biochemical labels or other bioengineered tags, and without contact to any surfaces. This opens up potentially important applications of DEP as a tool to address an unmet need in stem cell research and therapy.

Precision alignment and assembly of a Fourier transform microspectrometer

Integrating optics with MEMS presents numerous challenges in assembly and joining of heterogeneous components, stringent alignment of parts, packaging of the device to protect it, etc. Microspectrometers are examples of MOEMS devices where these issues play a significant role to the performance of the device. The motivation behind miniaturization of the spectrometer is strong, because traditional spectrometers are table-top instruments, and they are generally too large, and too costly to be ported outside of lab environments. Micro-Electro-Mechanical-Systems (MEMS) technology combined with microassembly offers promising possibilities to achieve compact and cost-effective miniaturization in such instruments. In this paper, we present a fiber-coupled Fourier-Transform microspectrometer with a nominal size of 3cmx3cmx3cm, constructed using 3D hybrid microassembly and targeting wavelengths in the visible and NIR spectra. We use modular micro scale parts, including minimum energy compliant MEMS fasteners to configure a die-sized microoptical bench. Light coupling, miniature electronics and power are included in a spectrometer package. In order to achieve the required precision on the microoptical bench we employ automated assembly of microcomponents. We present a systematic two-step assembly & alignment scheme (coarse and fine) using an image-based spot Jacobian algorithm. In this paper we present details related to design, tolerance analysis, calibration, microassembly and visual servoing techniques as well as spectrum data recovery for a completed prototype.

Development of a novel protective cover for micro manipulation process in the SEM chamber

This paper presents a novel approach to assembly of micro components in a scanning electron microscope (SEM) chamber. A new set, called Protective Cover for micro components allows their quick positioning on the platform inside the SEM chamber without gluing. It is well known that the vacuum pumps, especially turbo one, which evacuated a SEM chamber, are highly sensitive to foreign object damage. This is the reason why the micro components are glued on the specimen holder in the SEM chamber. On the other hand, the grippers that have to pick, lift and place the micro components in a desired system (position, orientation) are very fragile. They can not overcome the adhesive force of the glue and remove the particle from the specimen holder. The presented system is standardized and can be mounted without additional time, modification or expenses into the SEM chamber. It enables, on the one hand, easier manipulation of the micro components that do not need to be glued on the specimen holder and, on the other hand, introduces further automation in the manipulation process in the SEM chamber since it creates thus a necessary basis for modular assembling system. Furthermore, it is very important for the automated assembly process that the micro components are exactly positioned. The standardization in the micro world becomes more and more essential. The uniformity of parts, operations and tools strongly supports an automatic assembly system.