Design and Modeling of a Mems-Based Valveless Pump Driven by an Electromagnetic Force
A novel valveless micro impedance pump is proposed and analyzed in this study.
cs.OH↗
SEARCH · Searcharxiv
Results for “cs.OH”
Search indexed arXiv papers on artificial intelligence, large language models, computer vision and robotics. Read source abstracts and follow links to arXiv.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Electrostatic Actuators Operating in Liquid Environment : Suppression of Pull-in Instability and Dynamic Response
This paper presents results about fabrication and operation of electrostatic actuators in liquids with various permittivities. In the static mode, we provide experimental and theoretical demonstration that the pull-in effect can be shifted beyond one third of the initial gap and even be eliminated when electrostatic actuators are operated in liquids. This should benefit to applications in microfluidics requiring either binary state actuation (e.g. pumps, valves) or continuous displacements over the whole gap (e.g. microtweezers). In dynamic mode, actuators like micro-cantilevers present a great interest for Atomic Force Microscopy (AFM) in liquids. As this application requires a good understanding of the cantilever resonance frequency and Q-factor, an analytical modeling in liquid environment has been established. The theoretically derived curves are validated by experimental results using a nitride encapsulated cantilever with integrated electrostatic actuation. Electrode potential screening and undesirable electrochemistry in dielectric liquids are counteracted using AC-voltages. Both experimental and theoretical results should prove useful in micro-cantilever design for AFM in liquids.
cs.OH↗
Au-SN Flip-Chip Solder Bump for Microelectronic and Optoelectronic Applications
As an alternative to the time-consuming solder pre-forms and pastes currently used, a co-electroplating method of eutectic Au-Sn alloy was used in this study. Using a co-electroplating process, it was possible to plate the Au-Sn solder directly onto a wafer at or near the eutectic composition from a single solution. Two distinct phases, Au5Sn and AuSn, were deposited at a composition of 30at.%Sn. The Au-Sn flip-chip joints were formed at 300 and 400 degrees without using any flux. In the case where the samples were reflowed at 300 degrees, only an (Au,Ni)3Sn2 IMC layer formed at the interface between the Au-Sn solder and Ni UBM. On the other hand, two IMC layers, (Au,Ni)3Sn2 and (Au,Ni)3Sn, were found at the interfaces of the samples reflowed at 400 degrees. As the reflow time increased, the thickness of the (Au,Ni)3Sn2 and (Au,Ni)3Sn IMC layers formed at the interface increased and the eutectic lamellae in the bulk solder coarsened.
cs.OH↗
Contactless Thermal Characterization Method of PCB-s Using an IR Sensor Array
In this paper the feasibility study of an IR sensor card is presented. The methodology and the results of a quasi real-time thermal characterization tool and method for the temperature mapping of circuits and boards based on sensing the infrared radiation is introduced. With the proposed method the IR radiation-distribution of boards from the close proximity of the sensor card is monitored in quasi real-time. The proposed method is enabling in situ IR measurement among operating cards of a system e.g. in a rack.
cs.OH↗
Miniaturized Fluorescence Excitation Platform with Optical Fiber for Bio-Detection Chips
This paper presents a new research study on the platform fabrication of fluorescence bio-detection chip with an optical fiber transmission. Anisotropic wet etching on (100) silicon wafers to fabrication V-groove for optical fiber alignment and micro-mirror were included. Combing with anodic bonding technique to adhere glass, silicon structure and optical fiber for a fluorescence excitation platform was completed. In this study, the etching solution 40% KOH was used to study the parameters effect. The results show that working temperature is the main parameter to significantly effect the etch rate. The anisotropic etching resulted 54.7 degrees reflective mirrors and its reflectivity for optical beam were also examined. The surface roughness of the micro-mirror is Ra 4.1 nm measured using AFM, it provides excellent optical reflection. The incident light and beam profiles were also examined for further study. This study can show this micro-platform adaptable for fluorescence bio-detection.
cs.OH↗
Characterization of Flexible RF Microcoil Dedicated to Surface Mri
In Magnetic Resonance Imaging (MRI), to achieve sufficient Signal to Noise Ratio (SNR), the electrical performance of the RF coil is critical. We developed a device (microcoil) based on the original concept of monolithic resonator. This paper presents the used fabrication process based on micromoulding. The dielectric substrates are flexible thin films of polymer, which allow the microcoil to be form fitted to none-plane surface. Electrical characterizations of the RF coils are first performed and results are compared to the attempted values. Proton MRI of a saline phantom using a flexible RF coil of 15 mm in diameter is performed. When the coil is conformed to the phantom surface, a SNR gain up to 2 is achieved as compared to identical but planar RF coil. Finally, the flexible coil is used in vivo to perform MRI with high spatial resolution on a mouse using a small animal dedicated scanner operating at in a 2.35 T.
cs.OH↗
Integration of Micro-Electro-Mechanical Deformable Mirrors in Doped Fiber Amplifiers
We present a simple technique to produce active Q-switching in various types of fiber amplifiers by active integration of an electrostatic actuated deformable metallic micro-mirror. The optical MEMS (MOEMS) device acts as one of the laser cavity reflectors and, at the same time, as switching/ modulator element. We aim to obtain laser systems emitting short, high-power pulses and having variable repetition rate. The electro-mechanical behavior of membrane (bridge-type) was simulated by using electrostatic and modal 3D finite element analysis (FEA). The results of the simulations fit well with the experimental mechanical, electrical and thermal measurements of the components. In order to decrease the sensitiveness to fiber-mirror alignment we are developing novel optical devices based on stressed-metal cantilever-type geometry that allow deflections up to 50 $μ$m with increased reflectivity discrimination during actuation.
cs.OH↗
Micro-Ball Lens Array Fabrication in Photoresist Using Ptfe Hydrophobic Effect
This paper presents a simple method to fabricate micro-ball lens and its array. The key technology is to use the hydrophobic characteristics of polyterafluoroethylene (PTFE) substrate. High contact angle between melted photoresist pattern and PTFE can generate micro-ball lens and its array. PTFE thin film was spun onto a silicon wafer and dried in oven. Photoresist AZ4620 was used to pattern micro-columns with different diameters 60, 70 and 80 $μ$m. A thermal reflow process then was applied to melt these micro-column patterns resulted in micro-ball lens array. The achieved micro-ball lens array with diameter 98 $μ$m was fabricated using 80 $μ$m in diameter patterns. This method provides a simple fabrication process and low material cost.
cs.OH↗
Reduced-Order Modelling of the Bending of an Array of Torsional Micromirrors
Reduced-Order Modelling of the Bending of an Array of An array of micromirrors for beam steering optical switching has been designed in a thick polysilicon technology. A novel semi-analytical method to calculate the static characteristics of the micromirrors by taking into account the flexural deformation of the structure is presented. The results are compared with 3D coupled-field FEM simulation.
cs.OH↗
Model of Electrostatic Actuated Deformable Mirror Using Strongly Coupled Electro-Mechanical Finite Element
The aim of this paper is to deal with multi-physics simulation of micro-electro-mechanical systems (MEMS) based on an advanced numerical methodology. MEMS are very small devices in which electric as well as mechanical and fluid phenomena appear and interact. Because of their microscopic scale, strong coupling effects arise between the different physical fields, and some forces, which were negligible at macroscopic scale, have to be taken into account. In order to accurately design such micro-electro-mechanical systems, it is of primary importance to be able to handle the strong coupling between the electric and the mechanical fields. In this paper, the finite element method (FEM) is used to model the strong coupled electro-mechanical interactions and to perform static and transient analyses taking into account large mesh displacements. These analyses will be used to study the behaviour of electrostatically actuated micro-mirrors.
cs.OH↗
New Internal Stress Driven on-Chip Micromachines for Extracting Mechanical Properties of Thin Films
A new concept of micromachines has been developed for measuring the mechanical properties of thin metallic films. The actuator is a beam undergoing large internal stresses built up during the deposition process. Al thin films are deposited partly on the actuator beam and on the substrate. By etching the structure, the actuator contracts and pulls the Al film. Full stress strain curves can be generated by designing a set of micromachines with various actuator lengths. In the present study, the displacements have been measured by scanning electronic microscopy. The stress is derived from simple continuum mechanics relationships. The tensile properties of Al films of various thicknesses have been tested. A marked increase of the strength with decreasing film thickness is observed.
cs.OH↗
Process Issues for a Multi-Layer Microelectrofluidic Platform
We report on the development of some process capabilities for a polymer-based, multi-layer microelectrofluidic platform, namely: the hot embossing process, metallization on polymer and polymer bonding. Hot embossing experiments were conducted to look at the effects of load applied, embossing temperature and embossing time on the fidelity of line arrays representing micro channels. The results revealed that the embossing temperature is a more sensitive parameter than the others due to its large effect on the polymer material's viscoelastic properties. Dynamic mechanical analysis (DMA) on polymethyl methacrylate (PMMA) revealed a steep glass transition over a 20 oC range, with the material losing more than 95 % of its storage modulus. The data explained the hot embossing results which showed large change in the embossed channel dimensions when the temperature is within the glass transition range. It was demonstrated that the micro-printing of silver epoxy is a possible low-cost technique in the mass production of disposable lab chips. An interconnecting network of electrical traces was fabricated in the form of a four-layer PMMA-based device. A four PMMA layer device with interconnecting microfluidic channels was also fabricated and tested.
cs.OH↗
Fabrication of Switches on Polymer-Based by Hot Embossing
In MEMS technology, most of the devices are fabricated on glass or silicon substrate. However, this research presents a novel manufacture method that is derived from conventional hot embossing technology to fabricate the electrostatic switches on polymer material. The procedures of fabrication involve the metal deposition, photolithography, electroplating, hot embossing and hot embed techniques. The fundamental concept of the hot embed technology is that the temperature should be increased above Tg of polymer, and the polymer becomes plastic and viscous and could be molded. According to the fundamental concept, the metal layer on the silicon/glass substrate could be embedded into polymer material during the hot embossing process. Afterward, the metal layer is bonded together with the polymer after removing the substrate in the de-embossing step. Finally, the electrostatic switch is fabricated on polymethylmethacrylate(PMMA) material to demonstrate the novel method.
cs.OH↗
A New Model of Fringing Capacitance and its Application to the Control of Parallel-Plate Electrostatic Micro Actuators
Fringing field has to be taken into account in the formulation of electrostatic parallel-plate actuators when the gap separating the electrodes is comparable to the geometrical dimensions of the moving plate. Even in this case, the existing formulations often result in complicated mathematical models from which it is difficult to determine the deflection of the moving plate for given voltages and therefore to predict the necessary applied voltages for actuation control. This work presents a new method for the modeling of fringing field, in which the effect of fringing field is modeled as a serial capacitor. Numerical simulation demonstrates the suitability of this formulation. Based on this model, a robust control scheme is constructed using the theory of input-to-state stabilization (ISS) and back-stepping state feedback design. The stability and the performance of the system using this control scheme are demonstrated through both stability analysis and numerical simulation.
cs.OH↗
Fluoroscopy-based navigation system in spine surgery
The variability in width, height, and spatial orientation of a spinal pedicle makes pedicle screw insertion a delicate operation. The aim of the current paper is to describe a computer-assisted surgical navigation system based on fluoroscopic X-ray image calibration and three-dimensional optical localizers in order to reduce radiation exposure while increasing accuracy and reliability of the surgical procedure for pedicle screw insertion. Instrumentation using transpedicular screw fixation was performed: in a first group, a conventional surgical procedure was carried out with 26 patients (138 screws); in a second group, a navigated surgical procedure (virtual fluoroscopy) was performed with 26 patients (140 screws). Evaluation of screw placement in every case was done by using plain X-rays and post-operative computer tomography scan. A 5 per cent cortex penetration (7 of 140 pedicle screws) occurred for the computer-assisted group. A 13 per cent penetration (18 of 138 pedicle screws) occurred for the non computer-assisted group. The radiation running time for each vertebra level (two screws) reached 3.5 s on average in the computer-assisted group and 11.5 s on average in the non computer-assisted group. The operative time for two screws on the same vertebra level reaches 10 min on average in the non computer-assisted group and 11.9 min on average in the computer-assisted group. The fluoroscopy-based (two-dimensional) navigation system for pedicle screw insertion is a safe and reliable procedure for surgery in the lower thoracic and lumbar spine.
cs.OH↗
Robot-based tele-echography: clinical evaluation of the TER system in abdominal aortic exploration
OBJECTIVE: The TER system is a robot-based tele-echography system allowing remote ultrasound examination. The specialist moves a mock-up of the ultrasound probe at the master site, and the robot reproduces the movements of the real probe, which sends back ultrasound images and force feedback. This tool could be used to perform ultrasound examinations in small health care centers or from isolated sites. The objective of this study was to prove, under real conditions, the feasibility and reliability of the TER system in detecting abdominal aortic and iliac aneurysms. METHODS: Fifty-eight patients were included in 2 centers in Brest and Grenoble, France. The remote examination was compared with the reference standard, the bedside examination, for aorta and iliac artery diameter measurement, detection and description of aneurysms, detection of atheromatosis, the duration of the examination, and acceptability. RESULTS: All aneurysms (8) were detected by both techniques as intramural thrombosis and extension to the iliac arteries. The interobserver correlation coefficient was 0.982 (P < .0001) for aortic diameters. The rate of concordance between 2 operators in evaluating atheromatosis was 84% +/- 11% (95% confidence interval). CONCLUSIONS: Our study on 58 patients suggests that the TER system could be a reliable, acceptable, and effective robot-based system for performing remote abdominal aortic ultrasound examinations. Research is continuing to improve the equipment for general abdominal use.
cs.OH↗
Towards 3D ultrasound image based soft tissue tracking: a transrectal ultrasound prostate image alignment system
The emergence of real-time 3D ultrasound (US) makes it possible to consider image-based tracking of subcutaneous soft tissue targets for computer guided diagnosis and therapy. We propose a 3D transrectal US based tracking system for precise prostate biopsy sample localisation. The aim is to improve sample distribution, to enable targeting of unsampled regions for repeated biopsies, and to make post-interventional quality controls possible. Since the patient is not immobilized, since the prostate is mobile and due to the fact that probe movements are only constrained by the rectum during biopsy acquisition, the tracking system must be able to estimate rigid transformations that are beyond the capture range of common image similarity measures. We propose a fast and robust multi-resolution attribute-vector registration approach that combines global and local optimization methods to solve this problem. Global optimization is performed on a probe movement model that reduces the dimensionality of the search space and thus renders optimization efficient. The method was tested on 237 prostate volumes acquired from 14 different patients for 3D to 3D and 3D to orthogonal 2D slices registration. The 3D-3D version of the algorithm converged correctly in 96.7% of all cases in 6.5s with an accuracy of 1.41mm (r.m.s.) and 3.84mm (max). The 3D to slices method yielded a success rate of 88.9% in 2.3s with an accuracy of 1.37mm (r.m.s.) and 4.3mm (max).
cs.OH↗
The Fast Fibonacci Decompression Algorithm
Data compression has been widely applied in many data processing areas. Compression methods use variable-size codes with the shorter codes assigned to symbols or groups of symbols that appear in the data frequently. Fibonacci coding, as a representative of these codes, is used for compressing small numbers. Time consumption of a decompression algorithm is not usually as important as the time of a compression algorithm. However, efficiency of the decompression may be a critical issue in some cases. For example, a real-time compression of tree data structures follows this issue. Tree's pages are decompressed during every reading from a secondary storage into the main memory. In this case, the efficiency of a decompression algorithm is extremely important. We have developed a Fast Fibonacci decompression for this purpose. Our approach is up to $3.5\times$ faster than the original implementation.
cs.PF↗