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。     

基于PDMS的压电驱动式系列微型泵

为进一步拓展压电微泵的应用领域,以利于更好地将其集成于微流控芯片中,该文对以固态聚二甲基硅氧烷(PDMS)为泵体材料的压电微泵开展相关实验研究。通过合理设计压电振子的支承方式、阀片结构以及采用两腔串、并联结构等措施以提高压电微泵的工作性能。分别以PDMS和聚甲基丙烯酸甲酯(PMMA)为泵体材料设计制作了单腔微泵、双腔串、并联微泵,并对其工作性能进行对比性实验测试。实验证明,构造具有较好工作性能的PDMS压电微泵具有可行性,在电压90 V,频率80 Hz的情况下,PDMS双腔串联泵的输出流量达到21mL/min,输出压力达到10kPa。但与PMMA为泵体材料的压电微泵相比,PDMS压电微泵在流量、压力方面仍有近30%的差距。     

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.     

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.     

LIQUID-SOLID COUPLED SYSTEM OF MICROPUMP

This paper employs the integral-averaged method of thickness to approximate the periodical flows in a piezoelectric micropump, with a shallow water equation including nonlinearity and viscous damp presented to characterize the flows in micropump. The finite element method is used to obtain a matrix equation of fluid pressure. The fluid pressure equation is combined with the vibration equation of a silicon diaphragm to construct a liquid-solid coupled equation for reflecting the interaction between solid diaphragm and fluid motion in a micropump. Numerical results of a mode analysis of the coupled system indicate that the natural frequencies of the coupled system are much lower than those of the non-coupled system. The influence of additional mass and viscous damp of fluid on the natural frequencies of the coupled system is more significant as the pump thickness is small. It is found that the vibration shape functions of silicon diaphragm of the coupled system are almost the same as those of the non-coupled system. This paper also gives the first-order amplitude-frequency relationship of the silicon diaphragm, which is necessary for the flow-rate-frequency analysis of a micropump.     

无阀微泵泵腔中流体流动的有限元模拟与分析

采用有限元仿真软件ANSYS/FLOTRAN对收缩/扩张型无阀微泵泵腔中流体流动的全过程进行了数值模拟和仿真分析,得到了流体在整个泵腔中的流场构形和流动特性。结果表明,泵腔结构单元的弯道效应与出/入口处流体速度分布的非线性混合将导致腔中的局域涡流现象。通过对3个简单模型的模拟计算,证明了缓冲腔的不同结构对无阀微泵的整流效率有较大影响,是泵腔结构参数优化设计不可忽视的重要环节。     

微泵的结构与流体分析

利用扩散阀/喷嘴的流体特性设计了一种无活动阀压电式微泵;应用小挠度弹性弯曲理论,导出圆形压电复合层薄板的弹性曲面微分方程和复合层薄板的中性面位置方程;应用压电理论导出压电薄膜的边缘电场分布;应用微流体力学理论导出微泵单次循环的净流量。结合华盛顿大学的压电式微泵模型理论算出其最大流量为958μl/min,与其试验结果相吻合。     

继往开来,再创辉煌庆贺《军医进修学院学报》创刊30周年

在减少昂贵试剂消耗和提高生产能力的需求驱动下,微泵技术得到了广泛的关注和发展.利用声表面波流驱动的微泵在流体雷诺数很小的微尺度下具有一定优势,成为微流控系统中一种重要的补充技术.该文介绍了声表面波在微泵的研究现状,分析了基于表面波的微泵的基本原理,并设计了聚焦型叉指换能器实现微泵功能.对实验器件的设计、选择以及实验过程进行了介绍和分析,并对未来研究工作作出了总结.     

一种基于玻璃-PDMS微流控芯片上气动微泵的研制及其在化学发光分析中的应用研究

利用AZ4620光胶制备通道横截面为圆弧形的阳模,采用玻璃与PDMS材料的永久性封合技术,研制了一种玻璃-PDMS复合芯片微流控蠕动型气动微泵,实现单一微泵对多路液流的驱动．实验将该微泵系统应用于K3[Fe（CN）6]的化学发光检测,对4×10～mol／LK3[Fe（CN）6]测定的重现性为0．9％（RSD,n=7）,线性范围6×10^-6～6×10^-5mol／L,线性相关系数R^2=0．9990,检出限为8×10^-7mol／L．     

一种无阀压电微泵的研究

介绍了一种适用于微流体系统的无阀微泵。该微泵利用聚二甲基硅氧烷(PDMS)作为泵膜,利用硅各向异性腐蚀形成扩散口/喷口结构,并利用压电双晶片作为驱动部件。该微泵的制作工艺简单,使用寿命长,具有良好的液体驱动性能。对于使用15 mm长的压电双晶片作为驱动器的压电无阀微泵,在100 V6、0 Hz、占空比为1的方波驱动下,最大流速可达151μL/min。