Microfluidic devices for sample pretreatment and applications

With the fundamentals of microscale flow and species transport well developed, the recent trend in microfluidics has been to work towards the devices capable of dealing with ‘real’ crude samples directly. Before the real samples reaching the analytical step, it nearly requires significant pre-treated steps. Development of these microdevices that perform sample preprocessing steps is now underway for a broad range of application areas from on-chip DNA analysis, immunoassays to cytometry. This article provides an overview of the latest developments in microfluidic devices for sample pretreatment. Many of the microchips are being designed for individual preprocessing steps, but integration of multiple sample preparation steps has been shown, along with integration of sample preprocessing and analytical procedures on single microchips.     

Microfluidic devices harboring unsealed reactors for real-time isothermal helicase-dependent amplification

High-throughput microchip devices used for nucleic-acid amplification require sealed reactors. This is to prevent evaporative loss of the amplification mixture and cross-contamination, which may occur among fluidically connected reactors. In most high-throughput nucleic-acid amplification devices, reactor sealing is achieved by microvalves. Additionally, these devices require micropumps to distribute amplification mixture into an array of reactors, thereby increasing the device cost, and adding complexity to the chip fabrication and operation processes. To overcome these limitations, we report microfluidic devices harboring open (unsealed) reactors in conjunction with a single-step capillary based flow scheme for sequential distribution of amplification mixture into an array of reactors. Concern about evaporative loss in unsealed reactors have been addressed by optimized reactor design, smooth internal reactor surfaces, and incorporation of a localized heating scheme for the reactors, in which isothermal, real-time helicase-dependent amplification (HDA) was performed.     

基于形态仿生的海上溢油回收装置设计与评估

为解决海上溢油回收装置功能与形态单一的问题,提出一种自下而上的设计程序构建仿生设计方法。由综摄法求取生物特征意象集合以确定仿生目标集;结合哈里斯图表对目标集进行筛选以确定仿生原型;利用生物简化优化法分析仿生原型的结构特征关系,将结构特征与形态分析求得的设计要素进行耦合得到初步仿生造型设计方案;运用模糊数学中模糊集的概念对设计方案进行优先级排序;对择优方案进行模态分析,验证方案是否符合结构动力学要求,从而建立具有系统指导意义的仿生设计方法。利用方法指导设计,得到功能与形态间满足设计需求且高耦合度的蝠鲼仿生溢油回收装置。将该方法模型应用于产品仿生设计中,可以为海上应用类产品设计提供有效的理论指导,提高海洋技术类产品整体水平。     

Microfluidic electrodischarge devices with integrated dispersion optics for spectral analysis of water impurities

This paper reports a microfluidic device that integrates electrical and optical features required for field-portable water-chemistry testing by discharge spectroscopy. The device utilizes a dc-powered spark between a metal anode and a liquid cathode as the spectral source. Impurities are sputtered from the water sample into the microdischarge and characteristic atomic transitions due to them are detected optically. A blazed grating is used as the dispersion element. The device is fabricated from stacked glass layers, and is assembled and used with a charge-coupled device (CCD) sensing element to distinguish atomic spectra. Two structural variations and optical arrangements are reported. Detection of Cr and other chemicals in water samples has been successfully demonstrated with both devices. The angular resolution in terms of angular change per unit variation in wavelength (/spl part//spl theta///spl part//spl lambda/) is experimentally determined to be approximately 0.10 rad//spl mu/m, as opposed to the idealized theoretical estimate of 0.22 rad//spl mu/m. This is because the microdischarge is uncollimated and not a point source. However, this is sufficient angular resolution to allow critical spectra of metal impurities to be distinguished.     

Computer-aided measurement of transverse axon sections for morphology studies

A study has been made of a general-purpose minicomputer image analysis system to provide medical researchers with data needed in morphology studies of myelinated axon sections. The system was designed to provide data equivalent to that produced by manually outlining and quantifying the axon and myelin boundaries. The system hardware and algorithms are described and experimental results presented comparing manual and automated data. The results show that a system with limited automation is an order of magnitude faster than manual methods in providing data with comparable accuracy and improved repeatability.     

Shape sensitivity analysis and design studies for CAD flume sections

This paper presents shape design sensitivity analysis (DSA) and design studies for recreational waterslides represented in computer-aided design (CAD) environment. The mathematical representations of a number of commonly used flume sections that serve as the building blocks for waterslide configurations are created in CAD tools. Geometric dimensions of the individual sections that affect not only their geometric shape but also the overall configurations are identified as design variables. These design variables can be varied to search for better design alternatives, for example, safer waterslides. A set of coupled differential equations based on Lagrange’s equations of motion that describe the motion of the riding object are derived. The equations of motion incorporate friction forces between the riding object and the surface of the flume sections. These second-order differential equations are then solved using Mathematica. Based on the equations of motion and design variables identified, a set of differential equations are derived for calculating shape DSA coefficients. These equations are solved numerically again using Mathematica. The major contribution of the paper are (1) extending waterslide design parameterization and shape DSA computation to true CAD-based flume sections, which greatly alleviates the design for manufacturing issues previously encountered, (2) incorporating friction forces into shape DSA computation, and (3) developing a design scenario that includes sensitivity display and what-if studies for a compromised design that is safer and with a larger acceleration, therefore, higher excitement levels. Incorporating friction forces into the computation supports design for rider’s excitement levels, which are related to accelerations. Waterslide design will not be realistic without including friction forces.     

溢油应急决策中的设备优化调度方法研究

针对溢油应急,溢油应急设备库及其设备配置的特点,以溢油处理开始时间最早和调度的设备库数量最少为目标,在满足第一个目标的设备库集合中,分别采用穷举方法和贪心方法求取满足第二个目标的最优解。穷举方法保证能够获得最优解,但是计算复杂;贪心方法计算简单,适用于溢油应急设备的配置特点。用算例验证了该方法的有效性和高效性。     

Electrical characterization of integrated passive devices using thin film technology for 3D integration

With the development of 3D integration technology,microsystems with vertical interconnects are attracting attention from researchers and industry applications.Basic elements of integrated passive devices(IPDs),including inductors,capacitors,and resistors,could dramatically save the footprint of the system,optimize the form factor,and improve the performance of radio frequency(RF) systems.In this paper,IPDs using thin film built-up technology are introduced,and the design and characterization of coplanar waveguides(CPWs),inductors,and capacitors are presented.     

Piezoelectric ceramic bimorph coupled to thin metal plate as cooling fan for electronic devices

Several types of piezoelectric fans for cooling electronic devices were constructed and tested at 60 Hz, 110 V and 220 V, respectively. The aim of the work is to investigate the possibility of replacing the rotary type of fan in some noise-sensitive electronic devices. Different vibrating metal plates were tested and analyzed theoretically. It is found that the resonant frequency of the vibrating plate decreases with the increase of its length (l) if the length of the piezoelectric ceramic bimorph (L) is kept constant. The series-type fan with l=31.8 mm, made of phosphor bronze vibrating plate (S6), shows the highest value of fan tip displacement of 35.5 mm and produced wind velocity of 3.1 m/s driven by a 220 V, 60 Hz power source.     

Construction of near optimal meshes for 3D curved domains with thin sections and singularities for p-version method

The adaptive variable p- and hp-version finite element method can achieve exponential convergence rate when a near optimal finite element mesh is provided. For general 3D domains, near optimal p-version meshes require large curved elements over the smooth portions of the domain, geometrically graded curved elements to the singular edges and vertices, and a controlled layer of curved prismatic elements in the thin sections. This paper presents a procedure that accepts a CAD solid model as input and creates a curved mesh with the desired characteristics. One key component of the procedure is the automatic identification of thin sections of the model through a set of discrete medial surface points computed from an Octree-based tracing algorithm and the generation of prismatic elements in the thin directions in those sections. The second key component is the identification of geometric singular edges and the generation of geometrically graded meshes in the appropriate directions from the edges. Curved local mesh modification operations are applied to ensure the mesh can be curved to the geometry to the required level of geometric approximation.     

Use of optimal control theory for computing optimal injection policies for enhanced oil recovery

The theory of optimal control of distributed parameter systems has been applied to the problem of determining an optimum injection policy for a chemical flooding enhanced oil recovery process. The optimization criterion is to maximize the difference between gross revenue and cost of chemicals injected. Necessary conditions for optimality are obtained through application of the calculus of variations and the distributed weak minimum principle. A gradient method is used for the computation of optimal injection policies. The performance of the algorithm was examined for the surfactant injection in a one-dimensional flooding problem. Two types of interfacial tension behaviour were considered: a type ‘A’ system in which the interfacial tension is a monotically decreasing function with solute concentration and a type ‘B’ system in which a minimum in the interfacial tension occurs at a nominal surfactant concentration. Different initial values were used in order to establish the convergence of the computational algorithm. For a type ‘A’ system, the shape of the optimum injection strategy was not unique; however, there is a unique optimum for the amount of surfactant needed. For a type ‘B’ system, the shape of the optimum injection was unique as well as the amount injected. The results of this work show that given the properties of an oil reservoir and the properties of a surfactant solution, an optimum injection policy which minimizes a specific economic objective functional can be obtained using distributed parameter control theory.     

A low-power reference-less clock/data recovery for visible light communication devices requiring low data throughput

Microsystem Technologies - In this study a reference-less clock and data recovery (CDR) is designed and developed for the low speed visible light communication system based Internet of Things (IoT)...     

An efficient adaptive multigrid algorithm for predicting thin film flow on surfaces containing localised topographic features

Gravity-driven continuous thin film flow over a plane, containing well-defined single and grouped topographic features, is modelled as Stokes flow using lubrication theory. The associated time-dependent, nonlinear, coupled set of governing equations is solved using a full approximation storage (FAS) multigrid algorithm by employing automatic mesh adaptivity, the power, efficiency and accuracy of which is demonstrated by comparing the results with corresponding global fine-mesh solutions. These show that automatic grid refinement effectively restricts the use of fine grids to regions of rapid flow development which, for the topographies considered, includes the topography itself, the upstream Capillary ridge, downstream surge region, and the characteristic bow wave. It is shown that for the accurate solution of the associated lubrication equations, adaptive multigrid offers increased flexibility together with a significant reduction in memory requirement. This is further demonstrated by solving the problem of transient flow over a trench topography, generated by a sinusoidally varying inlet condition.     

Reverse engineering applications for recovery of broken or worn parts and re-manufacturing: Three case studies

Damaged or broken parts are generally too expensive to replace, or are no longer available. RE can be defined as: ‘Systematic evaluation of a product with the purpose of replication. This involves design of a new part, copy of an existing part, recovery of a damaged or broken part, improvement of model precision and inspection of a numerical model. Advantages of the technique include immediate feedback, data reduction, direct generation of geometry and higher precision of the final product. This paper shows some possibilities of use and benefit from utilising the RE-methodologies and techniques in production process, especially in the case when exists parts without 3D-CAD support.This paper, which defines obtaining CAD data step by step from damaged three different parts to reproduce or make a new design for some recoveries, has not get any technical drawings. When these parts had been recovered, some problems occurred. These problems have been solved by referring to some practical approaches. Establishing continuity across curve and surface patches is an important concept in the free form surface modeling. The CAD models were recovered and reconstructed to consider parametric and geometric continuity. The iso-phote method was used for surface continuity analysis. Hence, in this work, not only occurring problems but also solving methods were explained. Firstly, CAD models are created from damaged and broken parts by data digitization method by using CMM and the process was explored in detailed. Later, CAD models that had been obtained earlier are transferred into CAM module of the software and G codes are taken by the NC post-processor, and finally, the parts are manufactured by means of CNC milling machine. Additionally, this paper presents a review of the part digitization techniques available for reverse engineering.     

基于3层C/S和B/S混合模式的微生物采油信息系统

采油微生物菌种开发是微生物采油技术的首要问题也是核心问题。菌种信息不统一、不共享已成为进一步深化微生物采油技术研究和矿场应用的瓶颈,建立微生物采油信息系统是微生物采油进一步规范化发展的迫切需要。目前国内还没有这样一个数据库系统。根据采油微生物的特点,提出了7类22项用于描述菌种的参数指标,并利用油田现场主要油藏信息,进行了微生物采油信息系统的探索研究。该系统采用3层C／S和B／S混合模式,基于Internet／Intranet多层分布式系统,利用Windows 2000 server操作系统平台和Delphi、ASP等工具设计开发。建成后的系统可实现采油微生物菌种的综合管理、油藏信息和菌种信息的交互关联,从而实时、快速地在目的油藏应用微生物采油技术。