A Novel PDMS Microfluidic Spotter for Fabrication of Protein Chips and Microarrays

A novel polydimethyl siloxane (PDMS) microfluidic spotter system has been developed for the patterning of surface microarrays that require individually addressing each spot area and high probe density. Microfluidic channels are used to address each spot region, and large spot arrays can be addressed in parallel. Fluorescence intensity measurement of dye-spotted samples compared to control and pipetted drops demonstrated a minimum of three-fold increase in dye surface density compared to pin-spotted dyes. Surface plasmon resonance (SPR) measurement of protein-spotted samples as compared to pin-spotted samples demonstrated an 86-fold increase in protein surface concentration. The spotting system has been applied successfully to protein microarrays for SPR applications, in both a 12-spot linear and 48-spot two-dimensional (2-D) array format. This novel spotter system can be applied to the production of high-throughput arrays in the fields of genomics, proteomics, immunoassays, and fluorescence or luminescence assays.1565     

Applications of the Responsive Workbench

Many interface devices for virtual reality provide full immersion inside the virtual environment. This is appropriate for numerous applications that emphasize navigating through a virtual space. However, a large class of problems exists for which navigation is not the critical issue. Rather, these applications demand a fine-granularity visualization and interaction with virtual objects and scenes. This applies to a host of other applications typically performed on a desktop, table or workbench. Responsive Workbench technology offers a new way to develop virtual environments for this rather sizable class of applications. The Responsive Workbench operates by projecting a computer-generated, stereoscopic image off a mirror and through a table surface. Using stereoscopic shuttered glasses, users observe a 3D image displayed above the tabletop. By tracking the group leader's head and hand movements, the Responsive Workbench permits changing the view angle and interacting with the 3D scene. Other group members observe the scene as the group leader manipulates it, facilitating communication among observers. Typical methods for interacting with virtual objects on the workbench include speech recognition, gesture recognition and a simulated laser pointer (stylus). This article features Responsive Workbench applications from four institutions that have pioneered this technology. The four applications are: visualization, situational awareness, collaborative production modeling and planning, and a virtual windtunnel     

Microfluidic motion for a direct investigation of solvent interactions with PDMS microchannels

Solid surface/liquid interactions play an important role in microfluidics and particularly in manipulation of films, drops and bubbles, a basic requirement for a number of lab-on-chip applications. The behavior of solvents in coated microchannels is difficult to be predicted considering theories; therefore, experimental methods able to estimate the properties at the interface in real time and during the operational regime are amenable. Here, we propose to use an experimental setup to evaluate the effective dynamics of solvents inside PDMS microchannels. The influence of the solvent properties as well as of the channel wall’s wettability on the fluid movements was evaluated. Modification of the channel properties was achieved by introducing Teflon coatings that allow producing stable hydrophobic microchannel walls. The results were fitted according to Washburn-type power-law and compared with theoretical calculations of the parameter β that expresses the dependence of capillary dynamics on surface tension γ, liquid viscosity η, contact angles θ and the hydraulic radius R _H. A comparison between the calculated and the experimental values reveled that parameters other than the contemplated ones influenced the measurements. The main parameter that affects the flow of solvents such as water, methanol ethanol, dimethylformamide, acetonitrile and acetone was found to be the γ/η ratio. Considering these results, the investigation tool described here is believed to be promising to predict the dynamics of common organic solvents inside integrated functional fluidic devices and to accurately control solvent flow, particularly in capillary-driven pumpless systems, a basic requirement for widening the application range of PDMS lab-on-chip devices.     

A Micromachined Kelvin Probe With Integrated Actuator for Microfluidic and Solid-State Applications

This paper reports on a micromachined Kelvin probe structure with an integrated scanning tip and an integrated electrothermal actuator that provides axial dithering motion. The device is fabricated from metal foil by a modified microelectrodischarge machining process that allows electrical isolation within the device. In particular, it permits the incorporation of a wide epoxy plug that creates an insulating gap with low parasitic capacitance between the probe and the actuator. The epoxy structures are found to withstand the thermal and mechanical conditions encountered during device operation. The device is used to measure changes in the external surface potential of a parylene microfluidic channel as a function of varying pH of liquid inside the channel. A contact potential difference of$approx 6~ V$is measured for a change in pH from 4 to 8 within the channel. The device is also used to map embedded charge in a thin$ SiO_2$layer on a Si substrate, showing it to be suitable for monitoring microelectronics manufacturing processes.hfillhbox[1072]     

Liquid Aspiration and Dispensing Based on an Expanding PDMS Composite

In this paper, we present the development of active liquid aspiration and dispensing units designed for vertical, as well as lateral, liquid aspiration. The devices are based on a single-use thermally expanding polydimethylsiloxane (PDMS) composite, which allows altering its surface topography by means of individually addressable integrated heaters. Devices are designed in order to create an enclosed cavity in the system, due to locally expanding the initially unstructured composite. This enables negative volume displacement and leads to the event of liquid aspiration. To enable this device functionality, two different techniques of selectively creating permanent PDMS bonds have been developed. One approach utilizes the plasma-assisted PDMS bonding technique, together with a patterned antistiction layer to form reversibly, as well as irreversibly, bonded regions. Another approach utilizes microcontact printing of PDMS curing agent, which serves as a patterned intermediate layer for adhesive bonding. Fabricated prototype devices successfully demonstrated the aspiration and release of liquid volumes ranging from 28 to 815 nL. The devices are entirely fabricated from low-cost materials, using wafer-level processes only and do not require external means for liquid actuation.     

UV Laser Micromachining of Polymers for Microfluidic Applications

We have recently begun to explore the use of UV laser ablation micromachining to construct microfluidic devices in polymers. This technique can create microchannels rapidly and modify the resulting polymer surface in a single step. By ablating under different atmospheres, it is possible to alter both the surface chemistries and physical surface morphologies of the microchannels. We have employed electroosmotic flow measurements, chemical mapping, and optical microscopy to characterize the microfluidic devices. In addition, we have studied the parameters affecting the ablation, such as the laser wavelength, laser fluence, laser firing repetition rate, and the material being ablated.     

A New Verification Rule and Its Applications

This paper describes a verification rule for loop programs, and shows how it can be used in conjunction with the invariant-relation theorem to facilitate verification of programs.     

A New Multiword Expression Metric and Its Applications

Multiword Expressions(MWEs) appear frequently and ungrammatically in natural languages.Identifying MWEs in free texts is a very challenging problem.This paper proposes a knowledge-free,unsupervised,and language-independent Multiword Expression Distance(MED).The new metric is derived from an accepted physical principle,measures the distance from an n-gram to its semantics,and outperforms other state-of-the-art methods on MWEs in two applications: question answering and named entity extraction.     

第三代快速以太网控制器及其应用

介绍了SMSC公司最新推出的第三代快速以太网控制器LAN91C111的特性、结构及其在一个基于IPSec的加密系统中的应用。     

Electronic Nose and Its Applications: A Survey

Machine Intelligence Research - In the last two decades, improvements in materials, sensors and machine learning technologies have led to a rapid extension of electronic nose (EN) related research...     

一种新的高线性OTA及其应用

提出一种高线性的OTA,并且实现在连续时间滤波器中的应用。OTA电路采用交叉耦合单元和差分对的互补结构的输入级,弥补传统OTA线性度的不足,解释提高OTA线性度原理。成功的实现所设计的OTA应用于连续时间滤波器中。最后,采用HSPICE对电路进行仿真验证,并与传统的结构的OTA进行比较,结果表明该电路正确可行,线性度高。     

一种新型混合遗传算法及其应用

针对遗传算法应用的局限性,引入新的种群择优交叉运算、变异运算、遗传边界算子和相互学习过程的思想,提出一种新型混合遗传算法,提高了算法的收敛速度和稳定性,数值算例验证了该算法的有效性和实用性。     

一种基于平行坐标的度量模型及其应用

分析了数据挖掘中可视化技术应用的特点与方法,给出了数据挖掘中可视对象与参数的确定及算法分解的方法,提出了一种基于平行坐标技术的度量指标体系,证明了其中的相关性质与结论,并给出基于平行坐标技术的度量模型以及在实验数据上的应用例.结果表明这种方法对于数据挖掘中的数据可视化表示是有效的.基于度量指标的可视化技术在对可视对象的分析处理上可以借助适用的数学方法建模与评测,这有助于数据挖掘可视化的研究与应用.     

A Multi-agent Based Evaluation Framework and Its Applications

The evaluation system is significant for assessment of technologies, experiments, energy cost and effectiveness, especially for the complicated engineering systems, such as energy systems, weapon systems and spacecraft systems. However, as engineering systems become more and more distributed and heterogeneous, evaluation frameworks need to be more universal, distributed and interactive. In this paper, we compare several typical evaluation frameworks and propose a novel evaluation framework based on multi-agent technology. We provide two case studies, indoor comfort system and technology assessment of spacecraft systems, respectively. The results show that the proposed framework can work efficiently.      

A Survey of Blue-Noise Sampling and Its Applications

In this paper, we survey recent approaches to blue-noise sampling and discuss their beneficial applications. We discuss the sampling algorithms that use points as sampling primitives and classify the s...     

泛蕴涵推理机及其应用

本文提出模糊系统中基于泛逻辑的泛蕴涵推理机,给出其在描绘函数图形时的应用,同时比较了它与Mamdani型和Lasen型两种模糊系统在描绘函数图形时的误差。分析和比较表明,在相同规则下含有泛蕴涵推理机的模糊系统产生的误差最低。     

复合系统的混沌同步控制及在半双工保密通信中的应用

在一定条件下,对多个工作站的复合混沌的混沌同步提出了控制设计方法,并把结果应用到半双工保密通信中,仿真实例利用了Ｃｈｕａ‘ｓ电路。     

Application of an Equilibrium Model for an Electrified Fluid Interface—Electrospray Using a PDMS Microfluidic Device

An experimental investigation of an electrified fluid interface is presented. The experimental findings are related to a previously developed analytical model of Gubarenko , which is used to determine when a fluidic interface under electrical stress is in equilibrium, and to observations reported in the literature. The effect of key parameters on causing the interface to rupture, form, and maintain an electrospray is investigated. The experimental results reveal the dependence of interface shape on operational parameters, the impact of the interface apex angle on equilibrium, the conditions that cause either dripping mode or cone-jet mode, and the structure of operational domains. This paper confirms predictions made using the analytical model, including the range of parameters that cause the onset and steadiness of a quasi-equilibrium (electrospray) state of the interface. Testing is performed using an electrospray emitter chip fabricated from two layers of Polydimethylsiloxane and one layer of glass. The model and experimental results assist in design decisions for electrospray emitters. Applications of electrified interfaces (electrosprays) are found in mass spectrometry, microfluidics, material deposition, and colloidal thrusters for propulsion.$hfill$[2008-0074]      

一种基于XML的复合事件模型及其订阅语言

基于内容的Pub/Sub系统能够为大范围软件集成提供松耦合的、可扩展的集成能力,越来越引起人们的重视.现存的方法主要集中在对单一事件的匹配,缺乏对复合事件模型及其订阅语言的研究.针对此问题,文章给出一种基于XML事件的复合事件模型及其订阅语言,该模型包括事件时序逻辑模型和事件复合模式,并扩展了XMLQL语言得到复合事件订阅语言EXML-QL支持事件复合模型和模式;最后,依据该订阅语言的特点构造复合事件匹配算法,给出该算法的分析和验证.     

温敏晶闸管及其应用

综述了温敏晶闸管的结构原理和特性以及工作参数的选择,并介绍了一些具体应用。