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Xiaowei Xu Lining Sun Liguo Chen Zhaozhong Zhou Junjian Xiao Yuliang Zhang 《Biomicrofluidics》2014,8(6)
Digital microfluidics based on electrowetting on dielectric is an emerging popular technology that manipulates single droplets at the microliter or even the nanoliter level. It has the unique advantages of rapid response, low reagent consumption, and high integration and is mainly applied in the field of biochemical analysis. However, currently, this technology still has a few problems, such as high control voltage, low droplet velocity, and continuity in flow, limiting its application. In this paper, through theoretical analysis and numerical simulation, it is deduced that a drive electrode with a crescent configuration can reduce the driving voltage. The experimental results not only validate this deduction but also indicate that crescent electrode can improve the droplet motion continuity and the success in split rate. 相似文献
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This paper presents integrated microfluidic lab-on-a-chip technology combining surface acoustic wave (SAW) and electro-wetting on dielectric (EWOD). This combination has been designed to provide enhanced microfluidic functionality and the integrated devices have been fabricated using a single mask lithographic process. The integrated technology uses EWOD to guide and precisely position microdroplets which can then be actuated by SAW devices for particle concentration, acoustic streaming, mixing and ejection, as well as for sensing using a shear-horizontal wave SAW device. A SAW induced force has also been employed to enhance the EWOD droplet splitting function. 相似文献
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分析推动企业突破关键技术的内外部动力因素及机会动力因素,测度各动力因素对提升企业创新能力的贡献率。建立贡献率测度模型,提出反映动力因素间关联作用的影响力系数、感应力系数的测算方法,并通过比对A企业的访谈评价与数据分析验证模型适用性。定量解释A企业突破关键技术过程中各动力因素的贡献,并在计算影响力系数和感应力系数的基础上提出外部动力因素、内部动力因素及机会动力因素的贡献率分别达到3113%、4811%、2076%才能达到最适优化。企业突破关键技术的效果体现在创新能力的提升上,这有赖于动力因素形成合力后的优化与协调,而最适优化则归因于调整各因素影响力系数和感应力系数之后的最优取值区间。 相似文献
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Digital microfluidics is an elegant technique based on single droplets for the design, composition, and manipulation of microfluidic systems. In digital microfluidics, especially in the electrowetting on dielectric (EWOD) system, each droplet acts as an independent reactor, which enables a wide range of multiple parallel biological and chemical reactions at the microscale. EWOD digital microfluidics reduces reagent and energy consumption, accelerates analysis, enables point-of-care diagnostic, simplifies integration with sensors, etc. Such a digital microfluidic system is especially relevant for droplet digital PCR (ddPCR), thanks to its nanoliter droplets and well-controlled volume distribution. At low DNA concentration, these small volumes allow less than one DNA strand per droplet on average (limited dilution) so that after a fixed number of PCR cycles (endpoint PCR), only the DNA in droplets containing the sequence of interest has been amplified and can be detected by fluorescence to yield an accurate count of the sequences of interest using statistical models. Focusing on ddPCR, this article summarizes the latest development and research on EWOD technology for droplet PCR over the last decade. 相似文献
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A tiny droplet containing nano∕microparticles commonly handled in digital microfluidic lab-on-a-chip is regarded as a micro-optical component with tunable transmittance at programmable positions for the application of micro-opto-fluidic-systems. Cross-scale electric manipulations of droplets on a millimeter scale as well as suspended particles on a micrometer scale are demonstrated by electrowetting-on-dielectric (EWOD) and particle chain polarization, respectively. By applying electric fields at proper frequency ranges, EWOD and polarization can be selectively achieved in designed and fabricated parallel plate devices. At low frequencies, the applied signal generates EWOD to pump suspension droplets. The evenly dispersed particles reflect and∕or absorb the incident light to exhibit a reflective or dark droplet. When sufficiently high frequencies are used on to the nonsegmented parallel electrodes, a uniform electric field is established across the liquid to polarize the dispersed neutral particles. The induced dipole moments attract the particles each other to form particle chains and increase the transmittance of the suspension, demonstrating a transmissive or bright droplet. In addition, the reflectance of the droplet is measured at various frequencies with different amplitudes. 相似文献
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Specific binding and magnetic concentration of CD8+ T-lymphocytes on electrowetting-on-dielectric platform 总被引：1，自引：0，他引：1
In the quest to create a low-power portable lab-on-a-chip system, we demonstrate the specific binding and concentration of human CD8+ T-lymphocytes on an electrowetting-on-dielectric (EWOD)-based digital microfluidic platform using antibody-conjugated magnetic beads (MB-Abs). By using a small quantity of nonionic surfactant, we enable the human cell-based assays with selective magnetic binding on the EWOD device in an air environment. High binding efficiency (～92%)of specific cells on MB-Abs is achieved due to the intimate contact between the cells and the magnetic beads (MBs) produced by the circulating flow within the small droplet. MBs have been used and cells manipulated in the droplets actuated by EWOD before; reported here is a cell assay of a clinical protocol on the EWOD device in air environment. The present technique can be further extended to capture other types of cells by suitable surface modification on the MBs. 相似文献
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This work proposes the use of charged droplets driven by the Coulombic force as solution-phase reaction chambers for biological microreactions. A droplet can be charged near an electrode under dc voltage by direct contact to the electrode. This process is called electrical charging of droplet (ECOD). This charged droplet can then be transported rapidly between electrodes following the arc of an electric field line by exploiting electrostatic force. As on-demand electrocoalescence, both alkalization of phenolphthalein and bioluminescence reaction of luciferase in the presence of adenosine triphosphate are studied to test the feasibility of the biochemical microreactors using ECOD. Two oppositely charged droplets are merged to have a color change immediately after microchemical reaction. The applicability of an ECOD-driven droplet to measurement of glucose concentration is also tested. The glucose concentration is measured using a colorimetric enzyme-kinetic method based on Trinder’s reaction [J. Clin. Pathol. 22, 158 (1969)]. The color change in the merged droplet is detected with an absorbance measurement system consisting of a photodiode and a light emitting diode. 相似文献
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A novel actuation method of transporting droplets by using electrical charging of droplet in a dielectric fluid 总被引：1，自引：0，他引：1
We evaluate the feasibility of manipulating droplets in two dimensions by exploiting Coulombic forces acting on conductive droplets immersed in a dielectric fluid. When a droplet suspended in an immiscible fluid is located near an electrode under a dc voltage, the droplet can be charged by direct contact, by charge transfer along an electrically conducting path, or by both mechanisms. This process is called electrical charging of droplet (ECOD). This charged droplet may then be transported rapidly by exploiting Coulombic forces. We experimentally demonstrate electrical actuation of a charged droplet by applying voltage sequences. A charged droplet is two dimensionally actuated by following the direction of the electrical field signal. The droplet does not contact the surface of the microfluidic chip when it moves. This characteristic is very advantageous because treatments of the substrate surfaces of microfluidic chip become simpler. In order to test the feasibility of using ECOD in a droplet-based microreactor, electrocoalescence of two oppositely charged droplets is also studied. When two droplets approach each other due to Coulombic attraction, a liquid bridge is formed between them. We postulate that if the applied electric field is weaker than a certain critical level, the two droplets coalesce instantaneously when the charges are exchanged and redistributed through this liquid bridge. 相似文献
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当前,科技创新能力提升和科技创新高质量发展成为时代主题,科技评价政策引导科技创新高质量发展的“指挥棒”作用日益突显。本文通过搜集2006—2018年各省市的科技评价政策文件,在优化科技评价政策量化量表的基础上,分别从政策力度、政策目标和政策措施三个层次对政策文本进行量化分析。研究发现：我国科技评价政策总体上呈现“起步晚发展快”的特点,政策目标主题向创新人才培育、区域创新扶持与知识产权保护转变,同时,科技评价政策的作用机理呈现“非线性”特征,政策目标的作用方向正由“数量制胜”向“质量取胜”转变。从科技评价政策与区域科技创新能力发展的关系看,科技评价政策虽然在一定程度上促进了科技创新能力的发展,但是其直接政策效力明显薄弱;科技评价政策的多重目标导致政策的协同效应不足,同时,政策目标与政策实施之间的不协调也削弱了政策效力,导致其“指挥棒”作用仍然有限。 相似文献
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This study experimentally verifies that the mixing process in a droplet can be enhanced by driving the droplet at resonant frequencies and at alternating driving frequencies using a parallel-plate electrowetting on dielectric device. The mixing time, which is defined as the time required for reaching the well-mixed state, in a resonant droplet is found to be significantly shorter than that in a non-resonant droplet. Besides, it is also found that a higher driving potential leads to a better mixing effect, especially at resonant frequencies. Furthermore, when a droplet is driven by alternating two driving frequencies, especially two resonant frequencies, the mixing efficiency is found to be significantly enhanced for a specific alternating duration of these two frequencies. 相似文献
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市场战略效能(marketing strategy effectiveness)决定了企业战略的价值,因此关于市场战略效能的研究已经成为国外学者关注的热点问题之一。基于网络理论和能力理论,探究了网络联系(network ties)和吸收能力(absorptive capacity)对企业的市场战略效能的影响。在文献回顾的基础上,构建了研究变量的维度及其研究的理论模型,并利用东北地区181份有效问卷进行了实证研究,结果表明,企业的网络联系(技术联系和市场联系)均对市场战略效能有重要的影响;而企业的吸收能力的维度之一市场吸收能力(market absorptive capacity)对市场战略效能的影响显著,技术吸收能力(technical absorptive capacity)对市场战略效能的影响不显著,但随着吸收能力的增强,企业的网络联系对市场战略效能的影响得到加强。最后讨论了本文的现实意义并指出了局限性。 相似文献
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随着开放式创新理论的发展,集成创新已成为中小企业提高创新能力和国际竞争力的一个关键路径.本文在相关文献综述的基础上,从信息集成能力、知识集成能力、技术集成能力、组织集成能力和战略集成能力五个维度构建企业集成能力影响创新绩效的概念模型,然后通过问卷调查和统计分析对相应的理论假设进行检验.最后,为我国中小企业如何通过提高集成能力提高创新绩效和获取竞争优势提供相应的对策建议. 相似文献
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基于"科学防范胜于救灾"的应急管理理念,从监测与预报能力、预警与发布能力以及预防与准备能力等三个方面构建指标体系,并引入变异系数对CRITIC法进行了改进,建立了基于改进CRITIC法的综合评价模型,形成了基于"三预"视角的区域气象灾害应急防御能力评价体系,该体系突出了"预报、预警、预防"在灾害防御中的重要地位。通过对中国31个省(市、自治区)的气象灾害应急防御能力进行实证分析,表明各区域气象灾害应急防御能力差异较为明显,呈现出东高、中中、西低的格局,且与经济发展水平呈现出高度的正相关性,这与现实情况基本相符,说明该评价体系具有较强的可操作性和实用性。 相似文献
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探讨如何优化营商环境,提高区域创新绩效,对推动高质量发展具有重要意义。基于对大数据发展下营商环境影响区域创新绩效的机制分析,以2008—2017年我国地级市及722家民营企业的面板数据为样本,构建动态面板模型,使用SYS-GMM估计法进行实证检验,得出：（1）优化营商环境虽在总体上有利于提升区域创新绩效,但在不同城市存在异质性,呈现出“非省会强、省会弱”的不均衡特征。（2）大数据发展与营商环境优化的契合是区域创新绩效提升的关键,尤其是在省会城市,其作用更强,但囿于技术学习能力,却在非省会城市作用不确定。（3）营商环境优化作用的不均衡区域特征源于交易成本的中介作用存在城市差异,在省会城市,大数据发展能激发出交易成本的中介作用,增强优化营商环境的间接作用,扭转“非省会强、省会弱”的区域不均衡特征,全面激发营商环境优化的创新绩效提升效应。 相似文献
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This paper concerns with the convergence of the discrete-time nonlinear extended state observer (ESO). Several kinds of discrete-time nonlinear ESO (NLESO) are proposed and then sufficient conditions based on linear matrix inequality (LMI) method are obtained to quantitatively reveal the relationship between the plant, the sampling interval, the parameter values of NLESO and its convergence. The theoretical results are verified by simulation using a motion control system. It shows that there may exist an optimal ωo for a certain fixed sampling interval, and a smaller sampling interval generally generates better performance. What’s more, the proposed digital implementations of NLESO improve its performance over traditional Euler approximation discretization method. 相似文献
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管理创新依附于由复杂要素和关系构成的特定组织系统,需要组织具备动态能力即持续更新、再造和整合内外部资源的能力作为支撑或保障。因此,基于理论层面动态能力对管理创新过程效力影响机理的探析,构建研究框架,并对264份有效问卷数据进行分析,研究结果提出了过程视角管理创新效力测度方法,明确了动态能力四维度间的相互影响关系,且清晰了动态能力不同维度对管理创新阶段效力的作用机理与路径,突显关系能力最显著的影响作用。 相似文献
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企业部门间关系对组织学习能力和绩效的影响是当前组织学习领域需要研究的重要问题。本文主要探讨企业部门间关系如何对组织学习能力和绩效产生影响。我们关注的部门间关系包括部门间目标一致性、部门间建设性争论和部门间心理安全。本文认为,部门间目标一致性能够使各部门更有意愿分享各自拥有的信息和知识;部门间建设性争论使各部门更有能力进行有效的互动和思考;部门间心理安全则会促使各部门能够更无顾虑地相互分享和探讨,形成更好的工作氛围和更多的知识交流活动。因而,这三种部门间关系都会对组织学习能力和绩效产生积极的影响。本文通过调查我国企业获得的272个样本统计分析表明,这三种部门间关系都对组织学习能力都有显著正向影响,而且以组织学习能力为中介来影响组织绩效。本文从企业部门间关系的新视角探索了影响组织学习能力的因素,丰富了组织学习理论;同时本文提出的管理实践中改善优化部门间关系从而提升组织学习能力的相关措施,也具有实践意义。论文最后还对今后研究的改进提出了若干建议。 相似文献