锥管坡面腔底无阀压电泵流场分析

针对坡面腔底无阀压电泵流量小的问题,提出并研制了一种锥管坡面腔底无阀压电泵,即将锥管与坡面腔底组合式新结构作为其无移动部件阀。首先,提出了锥管坡面腔底无阀压电泵结构并分析其工作原理,对泵流量进行理论分析;同时,运用Fluent软件的动网格功能对其内部流场模拟分析。仿真结果表明,该泵具有单向流动特性,在泵腔内部产生漩涡利于液体的混合搅拌。最后,加工制作了锥管坡面腔底无阀压电泵样机,并对该泵进行了流量试验。试验结果表明,驱动电压峰值为250V,频率为5 Hz时,最大流量为25.9mL/min,证明了锥管坡面腔底无阀压电泵的有效性。     

压电锥形流管无阀泵的研究——气穴现象

分析了压电锥形流管无阀泵的气穴现象,首先发生在高速吸入过程的振动子中心区域;同时利用气穴现象阐述了流体温度变化对泵流量影响的原因;最后通过实例说明了增加流量减少气穴现象发生的具体方法,为 泵的应用设计提供了依据。     

Combined Numerical and Experimental Investigation of a 15-cm Valveless Pulsejet

The pulsejet, due to its simplicity, may be an ideal micro propulsion system. In this paper, modern computational and experimental tools are used to investigate the operation of a 15-cm overall length valveless pulsejet. Gas dynamics, acoustics and chemical kinetics are studied to gain understanding of various physical phenomena affecting pulsejet operation, scalability, and efficiency. Pressure, temperature, thrust, and frequency are measured as a function of valveless inlet and exit lengths and different geometries. At this length scale, it is necessary to run the pulsejets on hydrogen fuel. Numerical simulations are performed utilizing CFX to model the 3-D compressible vicious flow in the pulsejet using the integrated Westbrook–Dryer single step combustion model. The turbulent flow and reaction rate are modeled with the k–ɛ model and the Eddy Dissipation Model (EDM), respectively. Simulation results provide physical insight into the pulsejet cycle; comparisons with experimental data are discussed.     

Multipumping flow systems devoid of computer control for process and environmental monitoring

In this paper we describe for the first time the use of astable multivibrator circuits for computer-less control of solenoid micropumps and application for analytical flow techniques. Triggering and powering were accomplished using the NE555 integrated circuit. The activation and deactivation time intervals were adjusted using 10-turn trimmer potentiometers. The potential and characteristics of the instrumentation were studied on a two-channel flow system injecting an indigo carmine indicator solution. Subsequently, a three-channel flow system was assembled and successfully applied to the determination of nitrite in well waters. One circuit was used to control the activation time intervals of three further circuits used for the control of the flow rates or pulsation of solenoid micropumps. These were used for driving carrier, reagent, and sample in an analytical flow system. In the present work, the utility of the circuits for the construction of simple multipumping flow systems was demonstrated. A main feature to be highlighted was the simplicity and very low costs of the controlling circuits, favouring economic and miniaturised flow analysers. Second, no expenses or knowledge are required for the usual software control of the solenoid micropumps. This allows working with every existing detector without considering any problems of software and control compatibility. Third, owing to these features, the proposed assembly is especially suited for simple monitoring analysers, sample provision from an environmental or industrial process, or chemical education.     

Compressed Air-Driven Continuous-Flow Thermocycled Digital PCR for HBV Diagnosis in Clinical-Level Serum Sample Based on Single Hot Plate

We report a novel compressed air-driven continuous-flow digital PCR (dPCR) system based on a 3D microfluidic chip and self-developed software system to realize real-time monitoring. The system can ensure the steady transmission of droplets in long tubing without an external power source and generate stable droplets of suitable size for dPCR by two needles and a narrowed Teflon tube. The stable thermal cycle required by dPCR can be achieved by using only one constant temperature heater. In addition, our system has realized the real-time detection of droplet fluorescence in each thermal cycle, which makes up for the drawbacks of the end-point detection method used in traditional continuous-flow dPCR. This continuous-flow digital PCR by the compressed air-driven method can meet the requirements of droplet thermal cycle and diagnosis in a clinical-level serum sample. Comparing the detection results of clinical samples (hepatitis B virus serum) with commercial instruments (CFX Connect; Bio Rad, Hercules, CA, USA), the linear correlation reached 0.9995. Because the system greatly simplified the traditional dPCR process, this system is stable and user-friendly.     

微流体器件在微量液体操作系统中的应用

概述了应用于微量液体操作的微流体器件、微流体器件的主要材料和制造。并分别说明各微流体器件(集流腔、微泵、微吸液器等)的主要结构和在微量液体操作中的功用。     

压电膜片的优化设计及在微泵中的应用

压电驱动是微机械系统(MEMS)微执行器最有发展前途的驱动方式之一。该文采用ANSYS有限元软件对压电膜片结构参数和在微执行器上的装配方法进行了优化设计,得到PZT/Si,PZT/Cu压电膜片结构的优化数据,将其应用于有阀微泵的研制。经测试,微泵压电驱动效果与仿真结果一致,微泵背压可达836 Pa,流量达1.4 mL/min。     

PDMS薄膜电磁微泵的原理与制作

铁硼永磁薄片以及下部的平面线圈。与硅膜相比，这种泵膜材料使用寿命长，物理化学性质稳定，光学特性和机械特性优良。下部的通电线圈与固连在泵膜上的钕铁硼相互作用，从而引起泵腔体积的变化，进而控制微量流体的进出。泵膜驱动面积为6mm×6mm，厚度为40μm，在频率为5Hz，80mA AC方波信号驱动下，竖直方向上位移可达300μm。     

电液动力微泵的改进

介绍了微型电液动力泵的优化设计和工艺改进。电液动力微泵制作工艺的改进包括:材料的选择,微电极的优化设计和封装工艺的改进。使用聚二甲基硅氧烷(PDMS)作为构建微流道的材料,采用浇注法制作了PDMS微流道,并采用阳极键合方式进行微泵的封装。使用无水乙醇为工作流体对微泵进行流动实验,在驱动电压为90 V时,电液动力微泵驱动流体的最大流速可以达到92 uL/min。     

Extra-column effects in multi-dimensional switching systems (MDSS) — GC

In order to permit valveless MDSS operation and easy column change, the hardware designed contains several connections. These can give rise to extra-column band broadening effects. In order to quantitate such effects, the packed-capillary column configuration (without trap) was used. The band broadening caused by the connections was found to be small: 120 ms². A more practical approach was used to check the performance of the trap (re-injection) in the capillary-trap-capillary column configuration. Here the results obtained with re-injection from the trap were compared with results obtained in transfer and heart-cutting modes while the trap was heated. Re-injection was tested with n-alkanes ranging from n-C₆ to n-C₂₈. A starting peak width of 1.6 s was found.