一种医用微型同心压电薄膜泵

设计开发了一种结构新颖，制作工艺简单，成本低，综合性能高的烈性药物输注用压电薄膜微型泵，介绍了微泵的结构设计、工作原理和性能测试。微泵具有在出口和入口两个方向上抵抗冲击载荷的能力和互锁的功能，适合于对外界环境要求苛刻的烈性药物输注。微泵不论液体还是气体为工作介质都具有良好的流量特性和较高的可靠性。同心双向阀结构克服了传统的单向阀并联结构两阀间易连通的缺点。高分子聚合物材料和特殊的加工装配工艺使得微泵即使在小批量单件生产的情况下成本依然低廉。因此，该种微泵更加接近实用化，具有广阔的应用前景。     

Resonantly driven piezoelectric micropump: Fabrication of a micropump having high power density

As a fluid power source for practical micromachines using fluid power such as in-pipe mobile micromachines, micropumps having high power density are required. In this paper, a piezoelectric micropump using resonance drive is fabricated with the size of φ 9×10 mm. It basically consists of a bellows as a flexible pump chamber, a piezoelectric actuator for oscillating the bellows, and cantilever type of two check valves. An additional mass is attached to the free end of the piezoelectric actuator to enlarge amplitude of the displacement at resonant point. Firstly, through basic experiments using tap water as a working fluid, frequency characteristics and load characteristics of the pressure-dependent flow rate are experimentally investigated with various additional masses and valve thicknesses for stable and high performance. Next, for pumping of fluids having much higher viscosity than tap water, some improvements such as redesign of check valves and an application of a boost pressure are performed. Through basic experiments on pump performances using silicone oil, the effectiveness of those improvements is verified. As a result, the feasibility of the resonantly driven piezoelectric micropump is confirmed.     

Performance analysis of valveless micropump with disposable chamber actuated through Amplified Piezo Actuator (APA) for biomedical application

The precise manipulation of fluid through pumping systems has been the technological challenge in microfluidic applications. The biomedical applications call for precise and accurate delivery of fluid through miniaturized pumping systems. This paper presents a novel valveless micropump for biomedical applications operated by the Amplified Piezo Actuator. Integrating the disposable chamber and reusable actuator with the proposed micropump allows the actuator to be reused and eliminates the possibility of infection or contagion. The micropump was fabricated using low-cost polymeric materials like Polymethylmethacrylate (PMMA), Silicone rubber through CNC milling, Laser Cutting, conventional moulding operation. The micropump chamber, nozzle/diffusers, and a bossed diaphragm constituted disposable part and Amplified Piezo Actuator with structural support formed the reusable part of the micropump. The bossed diaphragm of the pump chamber consists of a central cylindrical protrusion to reduce the force of adhesion on the diaphragm and transmit force required for micropump actuation. A theoretical analysis was performed to assess the effect of diaphragm thickness and the bossed region on the effective stiffness of the diaphragm, which in turn influences the deflection achieved. Besides, an analytical approach has been presented to address the effect of adhesive force on the diaphragm surface due to the residual fluid and chamber depth. The experimental characterization of the micropump was carried out to determine the optimal performance parameters with water, fluids mimicking blood plasma, and whole blood. Based on the experimental results, the pumping rate and head developed by the micropump have been significantly affected by factors such as bossed ratio, diaphragm thickness, depth of the micropump chamber, and viscosity of the fluid. The optimum configuration of the micropump cosidered silicone rubber diaphragm with thickness of 0.20 mm having a bossed ratio of 0.33 and a chamber depth of 1.25 mm. With the optimal operating parameters of 150 V sinusoidal input of frequency 5 Hz, the proposed micropump was capable of delivering 7.192 ml/min, 6.108 ml/min, and 5.013 ml/min of water and blood plasma, whole blood mimicking fluid with the maximum backpressure of 294.00 Pa, 226.243 Pa, and 204.048 Pa respectively. The corresponding resolution, i.e., pumping volume/stroke of the micropump was about 23.972 µl, 20.358 µl, and 16.708 µl, respectively.     

基于螺纹中径直接测量仪的设计研究

在机加工过程中,外螺纹的加工及检测是一个非常普遍的工序。为了达到准确测量外螺纹深度的目的,就必须准确确定有效螺纹的位置,去掉无效螺纹长度。因此,外螺纹主要检测两个方面：外螺纹中径和外螺纹深度。目前测量螺纹中径的方法一般操作都比较繁琐,且需要经过一系列的计算,误差较大且效率较低,针对以上问题,本文设计出了一种螺纹中径直接测量仪,把机械装置和弱电控制相结合,采用高精度直线位移传感器,根据大量实验证明,测量结果准确,能满足工程需要。     

微气泡执行器强化微混合的实验研究

微尺度流动的雷诺数(Re)比较低,其混合主要通过扩散来完成,因此需要较长的距离与时间才能混合均匀。为实现微尺度低Re数流体的快速均匀混合,以甲醇及染色甲醇为工质,采用脉冲电压激励微铂膜产生可控气泡,并以气泡周期性胀缩产生的脉冲压力为动力源,研究脉冲压力横向扰动产生的混沌流对微通道内流动混合的影响。结果表明:脉冲压力横向作用使流体的交界面产生了强烈的卷曲拉伸,有效地强化了混合,该微混合器能够在毫米级混合长度及毫秒级混合时间内快速均匀混合,脉冲频率越高,混合效果越好。本研究结果为解决微尺度下低Re数流动混合难题提供了一种有效的崭新手段。     

Light propagation in the micro-size capillary injected by high temperature liquid

The high temperature liquid is injected into the micro-size capillary and its light propagation behavior is investigated. We focus on two different liquid pumping methods. The first method can pump the high temperature liquid tin into the micro-size capillary by using a high pressure difference system. After pumping, a single mode fiber (SMF) connected with the optical carrier based microwave interferometry (OCMI) system is used to measure different liquid tin levels in the micro-size capillary. The second method can pump the room temperature engine oil into the capillary by using a syringe pump. This method can avoid the air bubbles when the liquids are pumped into the capillary.     

两腔压电泵结构与特性

介绍了两个压电振子所构成的两腔串联和两腔并联压电泵的结构及工作原理,分析了两个压电振子驱动方式(同步工作和交叉工作)对两种结构压电泵输出性能的影响规律。制作了两腔串联和两腔并联压电泵的试验样机,分别测试了两个腔体同步工作和交叉工作状态下压电泵的输出能力,并与理论分析的结果进行了对比。理论和试验两方面的研究结果表明,在相同驱动电压和频率条件下,两个腔体交叉工作时压电泵的输出能力较好,其中并联泵的流量最大,为单个腔体流量的2倍;而串联泵的流量串联泵压力最大,是单个腔体输出压力的2倍,同时其流量也有大幅度提高,约为单个腔体流量的1.4倍。     

油气水井远程监控系统开发与应用

油气水井监控系统适用于抽油机井、螺杆泵井、电泵井、自喷井、气举井、注水井,该系统通过安装在个测量点上的压力传感器、温度传感器、示功终端、电参数模块、流量计、现场音频视频设备等采集到各参数,可以自动分析动液面来智能调节抽油机的冲次,从而使泵处于最佳沉没度.现场的所有传感器都是无线的,现场不需布线,载荷传感器通过测量加速度来获取位移.     

Dynamics of liquid meniscus bridge of a vibrating disk: consideration of flow rheology

A modified Reynolds equation, which includes the effect of flow rheology, is derived to describe the flow behaviour of lubricant between the space of a magnetic head slider and a disk. Under the assumptions of a small vibration of the spacing, and zero contact angle of the liquid?solid interface, the dynamics of a liquid meniscus disk of finite radius is analysed. The time-dependent modified Reynolds equation is linearised, and solved, under the boundary condition considering Laplace pressure. The results show that the pressure and load carrying capacity consist of three terms, that is, the static meniscus force term, the spring term by the dynamic Laplace pressure, and time-dependent damping term by the flow rheology of the fluid. The flow rheology affects the static meniscus forces and the damping forces significantly as compared to the spring forces. The effects of flow rheology on the load carrying capacity are also discussed.     

Permittivity Measurements of Lossy Liquids at Millimeter-Wave Frequencies

A measurement system is described which allows the determination of the complex permittivity of high-loss liquids at millimeter waves. Basically, the setup consists of a waveguide interferometer whose unknown arm embodies a liquid holder irradiated by an open-ended rectangular waveguide. The sample thickness is varied by means of a piston driven by a micrometer screw. The bridge output then is read as a function of the liquid thickness. Best fitting between experimental and computed data through a suitable model of the system enables the permittivity to be determined. The system can operate, with high sensitivity, over the whole frequency range of the dominant mode propagating in the waveguide setup employed. System performance is described through a set of experimental results obtained on ethanol, methanol, and pure water at 20° C and 70 GHz.     

A skin-contact-actuated micropump for transdermal drug delivery

In this paper, a skin-contact-actuated dispenser/micropump for transdermal drug delivery applications is presented. The micropump consists of stacked polydimethylsiloxane layers mounted on a silicon substrate and operates based on the evaporation and condensation of a low-boiling-point liquid. Therefore, there is no need for a heater and a power source, since only the thermal energy provided by skin contact is required for the actuation. A prototype device with overall dimensions of 14 mm × 14 mm × 8 mm is fabricated and characterized. For a perfluoro compound working fluid (3M FC-3284), a flow rate of 28.8 μ L/min and a maximum back pressure of 28.9 kPa is measured.     

螺纹联接的耐久性及防松措施

重点分析了交变载荷作用下 ,螺纹联接的耐久性及其影响因素。增加预紧力和降低螺栓刚度是提高耐久性的有效措施。比较了常用的几种螺纹防松措施的防松性能及其适用场合     

激光冲击波驱动的新型微泵数值模拟

针对传统微泵结构复杂、制备困难等不足,提出了一种新型的基于激光冲击波力学效应的微泵驱动方法,使用该方法设计的微泵结构简单、易于制造、成本低,有利于微型化及与微机电系统(MEMS)集成。通过研究激光冲击波的力学模型,设计了无阀型微泵,并计算出其耦合模态。验证了该驱动方法的可行性;通过流固耦合仿真研究了激光的频率、占空比、功率密度、光斑直径等参数对微泵流量的影响,并进一步分析了流量的稳定性。研究结果表明,功率密度和光斑直径是影响流量的主要因素,占空比为0.6时微泵流量最大,微泵稳定工作后各脉冲流量相差不超过5%。     

泵腔结构参数对压电气泵性能影响

为了探究泵腔结构参数对压电气体隔膜泵性能的影响,该文设计了一种压电气体隔膜泵的泵腔结构。首先简述了泵腔的结构设计与工作原理,推导出泵腔出口气流速度的表达式,通过仿真得出泵腔高度、气孔直径对腔体内的瞬时气压、气流速度及气体流量的影响。最后制作了泵腔样机并应用在压电气体隔膜泵中,进行了实验测试及理论分析对比。结果表明,实验结果与理论分析相吻合,输出流量随着腔高的增大而减小,随着气孔直径的增大而增大,这为压电气体微泵的腔体设计提供了理论参考。     

Artificial Soft Cilia with Asymmetric Beating Patterns for Biomimetic Low‐Reynolds‐Number Fluid Propulsion

In nature, liquid propulsion in low‐Reynolds‐number regimes is often achieved by arrays of beating cilia with various forms of motion asymmetry. In particular, spatial asymmetry, where the cilia follow a different trajectory in their effective and recovery strokes, is an efficient way of generating flow in low Reynolds regimes. However, this type of asymmetry is difficult to mimic and control artificially. In this paper, an artificial soft cilium that comprises two pneumatic actuators that can be controlled individually is developed. These two independent degrees of freedom allow for the first time adjustment and study of spatial asymmetry in the cilium's beating pattern. Using low‐Reynolds‐number flow measurements, it is confirmed that spatial asymmetry allows for the generation of fluid propulsion. These two‐degree‐of‐freedom soft cilia provide a platform to study ciliary fluid transport mechanisms and to mimic biologic viscous propulsion.     

电磁驱动柔性振动膜无阀微泵

提出了一种新型微泵设计方案和制作工艺，将电磁驱动器与大振幅振动膜相结合，得到流量大、易于控制的新型微泵。该微泵结构简单，由硅橡胶(聚二甲基硅氧烷PDMS橡胶)振动膜和无阀泵泵体组成，将硅加工工艺和非硅加工工艺(电镀)相结合。采用电镀和硅橡胶加工方法将振动膜直接制作在一个硅片上；用电镀和体硅加工工艺将驱动线圈和无阀泵泵体制作在另一块硅片上，然后将两个硅片键合在一起。对该微泵的性能特点正进行着更深入的研究。     

Development of an implantable motor-driven assist pump system

A motor-driven artificial pump and its transcutaneous energy transmission (TET) system have been developed. The artificial pump consists of a high-speed dc brushless motor driving a ball screw and magnetic coupling mechanism between the blood pump and ball screw. The ball screw transfers high-speed rotary motion into low-speed rectilinear motion by a single component. Magnetic coupling enables active blood filling without applying an excess negative pressure to the pump. The transcutaneous transformer is formed from a pair of concave/convex ferrite cores. This design minimizes lateral motion of the external core. Information on motor voltage is transmitted through the skin by infrared pulses. The motor voltage is regulated by controlling the duty ratio of the square pulse supplied to the primary coil. Pump flow of 5.6 l/min was obtained with a mean outlet pressure of 100 mmHg at a drive rate of 100 bpm under preload of 15 mmHg. The performance of synchronous pumping has been very satisfactory. Continuous pumping was maintained by the backup battery in the case of interruption of TET. 24 W were transmitted by TET system with 78 percent of efficiency. Temperature rise of the internal core was 0.2 C. The developed system is promising as an implantable assist pump system.     

Bioinspired Continuous and Spontaneous Antigravity Oil Collection and Transportation

Liquids with low surface tension, such as petroleum, serve as the source of power for development of modern industry. Spontaneous and directional transportation of oily liquids in aqueous environment has drawn wide attentions owing to its scientific significance and practical prospect in marine petroleum exploitation and oil spill cleanup. Persistent effort has been made to the directional transportation of oil droplets under specific assistance. However, the spontaneous oriented movement of oil, especially the air/water two‐phase oil delivery is still identified as a big challenge. Here, a bioinspired superoleophobic pump has been fabricated through the assembly of a superoleophobic mesh and an oil column. Depending on the directional releases of surface energy, oil droplets can be continuously collected and pumped to centimeters high without additional driving forces. The antigravity oil delivery system can realize continuous oil flow under water, even the air/water two‐phase oil transportation. This work demonstrates a new mode of liquid transportation without external energy and should open a new way to design novel fluid delivery systems to realize diverse liquid transport.     

Double‐Twisted Conductive Smart Threads Comprising a Homogeneously and a Gradient‐Coated Thread for Multidimensional Flexible Pressure‐Sensing Devices

Fiber‐based, flexible pressure‐sensing systems have attracted attention recently due to their promising application as electronic skins. Here, a new kind of flexible pressure‐sensing device based on a polydimethylsiloxane membrane instrumented with double‐twisted smart threads (DTSTs) is reported. DTSTs are made of two conductive threads obtained by coating cotton threads with carbon nanotubes. One thread is coated with a homogeneous thickness of single‐walled carbon nanotubes (SWCNTs) to detect the intensity of an applied load and the other is coated with a graded thickness of SWCNTs to identify the position of the load along the thread. The mechanism and capacity of DTSTs to accurately sense an applied load are systematically analyzed. Results demonstrate that the fabricated 1D, 2D, and 3D sensing devices can be used to predict both the intensity and the position of an applied load. The sensors feature high sensitivity (between ≈0.1% and 1.56% kPa) and tunable resolution, good cycling resilience (>104 cycles), and a short response time (minimum 2.5 Hz). The presented strategy is a viable alternative for the design of simple, low‐cost pressure sensors.     

Flow and heat transfer in porous micro heat sink for thermal management of high power LEDs

A novel porous micro heat sink system is presented for thermal management of high power LEDs, which has high heat transport capability. The operational principle and heat transfer characteristics of porous micro heat sink are analyzed. Numerical model for the micro heat sink is developed to describe liquid flow and heat transfer based on the local thermal equilibrium of porous media, and it is solved with SIMPLE algorithm. The numerical results show that the heated surface temperature of porous micro heat sink is low at high heat fluxes and is much less than the bearable temperature level of LED chips. The heat transfer coefficient of heat sink is very high, and increasing the liquid velocity can enhance the average heat transfer coefficient. The overall pressure loss of heat sink system increases with the increasing the inlet velocity, but the overall pressure drop is much less than the pumping pressure provided by micro pump. The micro heat sink has good performance for thermal management of high power LEDs, and it can improve the reliability and life of LEDs.