高聚物微流控芯片上集成化气动微阀的研制

报道了一种新型的聚甲基丙烯酸甲酯(PMMA)/聚二甲基硅氧烷(PDMS)复合芯片。该芯片采用PMMA-PDMS…PDMS-PMMA的四层构型,以在芯片上集成气动微阀。具有液路和控制通道网路的PMMA基片与PDMS弹性膜间采用不可逆封接,分别形成液路半芯片和控制半芯片,而2个半芯片则依靠PDMS膜间的粘性实现可逆封接,组成带有微阀的全芯片。这种制备方法解决了制备PMMA-PDMS-PMMA三层结构芯片的封接难题,封接过程简单可靠。其控制部分和液路部分可以单独更换,可进一步降低使用成本,尤其适合一次性应用场合。初步实验表明:该微阀具有良好的开关性能和耐用性。     

A novel microdevice for the treatment of hydrocephalus: design and fabrication of an array of microvalves and microneedles

We present an implantable, microfabricated device for the treatment of hydrocephalus. Hydrocephalus is a medical condition, in which an abnormal accumulation of cerebrospinal fluid (CSF, a water-like fluid that circulates around and protects the brain and spinal cord.) occurs in the brain. The novel microdevice presented here mimics the function of natural one-way valves, arachnoid villi, found in the human brain. Hence, we name it microfabricated arachnoid villi (MAV). The MAV consists of an array of one-way microvalves and hollow microneedles. The one-way microvalves control flow based on pressure differential. A Parylene microvalve array with a dome petal geometry was designed and fabricated. Initial flow tests demonstrated the desired low cracking pressure of the valve and a sufficient mechanical stability. The hollow microneedle array was designed to pierce the dura mater membrane (A tough fibrous membrane covering the brain and the spinal cord and lining the inner surface of the skull.) and provide a conduit for CSF. An SU-8 microneedle array was designed and successfully microfabricated. The innovative MAV may open a new era in the treatment of hydrocephalus.     

On-chip manipulation and trapping of microorganisms using a patterned magnetic pathway

We demonstrate on-chip manipulation and trapping of individual microorganisms at designated positions on a silicon surface within a microfluidic channel. Superparamagnetic beads acted as microorganism carriers. Cyanobacterium Synechocystis sp. PCC 6803 microorganisms were immobilized on amine-functionalized magnetic beads (Dynabead^® M-270 Amine) by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC)–N-hydroxysulfosuccinimide coupling chemistry. The magnetic pathway was patterned lithographically such that half-disk Ni₈₀Fe₂₀ (permalloy) 5 μm elements were arranged sequentially for a length of 400 micrometers. An external rotating magnetic field of 10 mT was used to drive a translational force (maximum 70 pN) on the magnetic bead carriers proportional to the product of the field strength and its gradient along the patterned edge. Individual microorganisms immobilized on the magnetic beads (transporting objects) were directionally manipulated using a magnetic rail track, which was able to manipulate particles as a result of asymmetric forces from the curved and flat edges of the pattern on the disk. Transporting objects were then successfully trapped in a magnetic trapping station pathway. The transporting object moves two half-disk lengths in one field rotation, resulting in movement at ~24 μm s^?1 for 1 Hz rotational frequency with 5 μm pattern elements spaced with a 1 μm gap between elements.     

Development and fabrication of magnetic thin films

For designing and fabricating electromagnetic microactuators as pursued within the collaborate research center “Design and Fabrication of Active Microsystems” (Sonderforschungsbereich 516), soft and hard magnetic materials are required to create and guide magnetic flux. The investigations on the development of suitable materials and their deposition technologies are presented in this paper. In the area of soft magnetic materials, the application of Cobalt–Iron (CoFe) as an alternative to Nickel–Iron (NiFe, Permalloy) was investigated. The benefit of CoFe over NiFe is its greater saturation flux density. The technology utilized for the deposition was electroplating. In the area of hard magnetic materials, gas flow sputtering was applied for depositing Samarium–Cobalt (SmCo). This technology enables the deposition of pure SmCo layers at high deposition rates and without high vacuum. Furthermore, the dependence of the magnetic properties of the SmCo on the film composition was examined.     

基于永磁薄膜的MEMS磁传感器设计与制作

提出了一种基于永磁薄膜的新型MEMS磁传感器,磁传感器由MEMS扭摆、CoNiMnP永磁薄膜和差分检测电容等部分组成。分析了磁传感器的磁敏感原理和电容检测原理,提出了器件的结构参数并对器件进行了模态仿真。利用MEMS加工技术成功制作了MEMS磁传感器样品,并进行了测试。测试结果表明:得到的MEMS磁传感器的电容灵敏度可达到27.7 fF/mT,且具有良好的线性度。根据现有的微小电容检测技术,传感器的磁场分辨率可达到36 nT。     

宽线性GMI磁传感器的研制

用单辊快淬法制备的Fe76Si7.6B9.5P5C1.9非晶合金薄带,在540℃空气中退火后具有宽线性的磁敏特性。利用纵向驱动的方法研制一种巨磁阻抗（GMI）传感器,该磁传感器重复性好,迟滞误差小,在-0.3～＋0.3 kA·m-1范围具有比较好的线性度,灵敏度达到12.65mV/A·m-1。     

高灵敏巨磁阻抗小型磁传感器研制

利用单辊快淬法制备了CoFeNiSiB非晶薄带,经过400 A/mm2电流密度、20 ms脉冲间隔条件下的脉冲退火后具有较好的弱磁场灵敏性能.以该带材为磁敏材料,基于纵向驱动方式研制了一种巨磁阻抗(GMI)磁传感器,该磁传感器尺寸小、灵敏度高、频率响应好,±0.05 mT弱磁场范围内灵敏度可达到44.15 V/mT,在高灵敏度小型磁传感器领域具有较大的应用潜力.     

磁方位修正MEMS矢量水声传感器研制

介绍了一种磁方位补偿微机电系统(MEMS)矢量水声传感器.采用电容原理MEMS技术构造内部振子,并与信号处理电路紧靠方式设计,可减小噪声干扰并抑制信号衰减.利用磁方位修正技术,对MEMS矢量水声传感器判定的方位进行修正,解决了单个矢量水声传感器定向精度不高问题.传感器完成了国家一级计量站标定和磁方位误差修正测试,测试结果验证了定向方法的可行性,矢量水声传感器可实现水下目标探测、定位及导航等任务.     

Synthesis of magnetic hydrogel microparticles for bioassays and tweezer manipulation in microwells

We report new methods for the synthesis and efficient manipulation of magnetic hydrogel microparticles. Through the development of a high-pH rinsing scheme, we achieve a simple and flexible synthesis strategy for the generation of geometrically and chemically complex magnetic microgels, eliminating the need for perfusion streams and other features that limit production rates and particle complexity. We further demonstrate the ability to combine magnetic functionality with both coding and target capture motifs within the same barcoded particle for enhanced applications in microRNA detection. We use a magnetic tweezer to assist in the positioning of particles in substrate-patterned microwells, and also for selective retrieval of particles. The magnetic particle manipulations and the substrate-mediated patterning techniques described in this work hold great potential for the development of a versatile platform for nanoliter-scale reactions with multifunctional hydrogel microparticles.     

Scattering of electromagnetic radiation by a multilayered sphere

The computer implementation of the algorithm for the calculation of electromagnetic radiation scattering by a multilayered sphere developed by Yang, is presented. It has been shown that the program is effective, resulting in very accurate values of scattering efficiencies for a wide range of size parameters, which is a considerable improvement over previous implementations of similar algorithms. The program, named scattnlay, would be the first of its kind to be publicly available.

Program summary

Program title: scattnlayCatalogue identifier: AEEY_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEEY_1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Gnu General Public License (GPL)No. of lines in distributed program, including test data, etc.: 8932No. of bytes in distributed program, including test data, etc.: 175 276Distribution format: tar.gzProgramming language: ANSI CComputer: Any with a C compilerOperating system: Linux (any), Windows, SolarisRAM: ∼1-100 MBClassification: 1.3Nature of problem: The scattering of electromagnetic (EM) radiation by a multilayered sphere is an interesting phenomenon to study for the application of such materials in several fields. Just to mention two examples, metal nanoshells (a dielectric core surrounded by a metallic shell) are a class of nanoparticles with tunable optical resonances that can be used, among others, in medicine for optical imaging and photothermal cancer therapy; while in the field of atmospheric sciences, light absorption by aerosols has a heating effect in the atmosphere that is of great interest to study several climatic effects. Although at first glance the expressions of the scattering coefficients seem simple and straightforward to implement, they involve several numerical difficulties which make most of the existent algorithms inapplicable to several extreme cases. More recently, Yang [1] has developed an improved recursive algorithm that circumvents most of the numerical problems present in previous algorithms, which is implemented in the current program.Solution method: Calculations of Mie scattering coefficients and efficiency factors for a multilayered sphere as described by Yang [1], combined with standard solutions of the scattering amplitude functions.Restrictions: Single scattering, permeability of the layers is always unity.Running time: Seconds to minutesReferences:

[1]

W. Yang, Appl. Opt. 42 (2003) 1710-1720.

     

Design, fabrication and control of a magnetic capsule-robot for the human esophagus

Much research on the development of a robotic capsule and micro robot for the diagnosis of gastrointestinal diseases has been carried out. The powering of these micro systems is becoming very challenging as the implementation of such systems is limited due to the existence of on-board power supplies. This paper presents a micro robotic system based on magnetic principles. The goal is to build a system in which a capsule-robot can be manipulated wirelessly inside an enclosed environment such as human??s body. A prototype of capsule-robot is built and tested, that can be remotely operated with three DOF in an enclosed environment by transferring magnetic energy and electromagnetic waves. A magnetic drive unit generates magnetic energy for the manipulation. Experimental results show the capsule-robot is manipulated and moved through a desired trajectory in a viscous fluid. The capsule-robot can be potentially used for endoscopy and colonoscopy.     

Controllable fission of droplets and bubbles by pneumatic valve

We report a feasible method that can precisely control the fission of droplets by modulating the flow resistance using pneumatic valves. Multilayer soft lithography was used to fabricate the valves. They can be used as variable microfluidic resistor (VMR) to dramatically change the flow resistance. A simulation has been done to forecast the behavior of droplets. We used this technique to control break-up of generated droplets and direct their motion. Droplets with different volume ratios were obtained in one chip. To investigate the mechanism, an equivalent electrical circuit was introduced to compare with the fluid network. This method could potentially be applied to different geometries, especially for the microfluidic network consisting of a set of two parallel channels with a common inlet and different outlets in bifurcating channels. Besides, manipulation of bubbles was also demonstrated.     

Modeling and simulation of powered hip orthosis by pneumatic actuators

In this study, a simulation model for a powered hip orthosis (PHO) with air muscles to predict the gait of paraplegics is presented which can be used as a design tool for hip orthoses. Before simulation, mathematical models for a human dummy with an orthosis and a pneumatic muscle actuator were generated. For the air muscle, coefficients required were obtained by static and dynamic experiments of the air muscle and experiments for the valve controlling the air pressure. The computation was conducted on the ADAMS package together with MATLAB. Computer simulation of the flexion of hip joints by the pneumatic muscle results in similar values to those from gait analysis. With the development of a simulation model for a PHO, the gait simulation model using pneumatic muscles can be used to analyze and evaluate the characteristics and efficiency of a PHO by setting the input and boundary conditions.     

极限电流型氧传感器的多层共烧制备

实验采用5%摩尔钇含量氧化锆流延生瓷片,经过厚膜丝网印刷,叠片热压,多层共烧制备了氧化锆极限电流型氧传感器;通过热膨胀仪、数字显微镜、扫描电子显微镜(SEM)等手段对其进行了物理性能的表征,并对该传感器在923 K温度氧浓度1100×10-6～90%范围内的气敏特性、响应时间等进行了输出特性的研究.实验结果表明共烧制备的传感器在上述氧浓度范围内具有较好的电流平台,且极限电流与氧浓度存在正常扩散模型具有的线性关系;工作温度在923 K,氧浓度在21.24%和5.06%之间变化对应的传感器响应时间呈现出较好的重复性,且均在1 s以内.     

Development of a transformable wheel actuated by soft pneumatic actuators

Small mobile robots with transformable wheels have recently emerged thanks to their increased mobility and maneuverability. When a high payload is applied to these robots, however, wheel transformation becomes difficult because they must directly overcome the payload’s weight. In this paper, we propose a wheel that can be transformed from its starting circular shape (radius, 56 mm) to a wheel with three legs (radius, 99 mm) under a high payload with low operating force. The key design principle of this wheel is to kinematically decoupled legs and passive locking. Its legs are kinematically decoupled but operated by a single air pump using a pneumatic channel connected to soft pneumatic actuators installed at each leg. Application of pressure causes the legs to behave like a coupled system through the pneumatic channel. With pressurization, the two legs that are not in contact with the ground easily emerge from body, and the leg in contact with the ground emerges once the wheel rotates. Once emerged, each leg is supported by a rigid pawl instead of by the soft pneumatic actuators. This setup enables the legs to be transformed independently with low air pressure, even under high payloads. It reduces system weight and the energy required to maintain the transformed shape. This legged wheel can overcome obstacles up to 2.9 times the radius of the wheel in its circular form, and wheel transformation can be accomplished with 85 kPa air pressure for payloads up to 1115 g.     

Reliable magnetic reversible assembly of complex microfluidic devices: fabrication, characterization, and biological validation

Current standard procedures for fabrication of microfluidic devices combine polydimethylsiloxane (PDMS) replica molding with subsequent plasma treatment to obtain an irreversible sealing onto a glass/silicon substrate. However, irreversible sealing introduces several limitations to applications and internal accessibility of such devices as well as to the choice of materials for fabrication. In the present work, we describe and characterize a reliable, flexible and cost effective approach to fabricate devices that reversibly adhere to a substrate by taking advantage of magnetic forces. This is shown by implementing a PDMS/iron micropowder layer aligned onto a microfluidic layer and coupled with a histology glass slide, in union with either temporary or continuous use of a permanent magnet. To better represent the complexity of microfluidic devices, a Y-shaped configuration including lower scale parallel channels on each branch has been employed as reference geometry. To correctly evaluate our system, current sealing methods have been reproduced on the reference geometry. Sealing experiments (pressure control, flow control and hydraulic characterization) have been carried out, showing consistent increases in terms of maximum achievable flow rates and pressures, as compared to devices obtained with other available reversible techniques. Moreover, no differences were detected between cells cultured on our magnetic devices as compared to cells cultured on permanently sealed devices. Disassembly of our devices for analyses allowed to stain cells by hematoxylin and eosin and for F-actin, following traditional histological processes and protocols. In conclusion, we present a method allowing reversible sealing of microfluidic devices characterized by compatibility with: (i) complex fluidic layer configurations, (ii) micrometer sized channels, and (iii) optical transparency in the channel regions for flow visualization and inspection.     

磁敏感器复合薄膜巨磁阻抗效应的产生与增强机理研究

磁性层/导电层/磁性层结构合薄膜比单层膜具有更强的巨磁阻抗(GMI)效应,但其GMI效应产生和增强的机理尚不完全清楚.本文从经典电磁理论出发,建立了复合薄膜GMI效应的理论模型,利用模型仿真了典型的磁敏感器复合膜CoSiB/Cu/CoSiB的GMI特性及其内部电流的分布.通过研究得到结论:复合结构中的“类趋肤效应“是产生GMI效应的主要原因;各层之间的相互电磁作用和导电层的高电导率特性是使复合结构GMI效应得到加强的原因.     

磁流变抛光液磁性颗粒体积分数在线检测装置研制

分析了互感法检测磁流变抛光液中磁性颗粒体积分数的基本原理,并研制出相应的原型装置。该方法的测量输出电压与抛光液磁性颗粒体积分数呈线性关系,磁性颗粒体积分数变化1%时输出电压变化约23.4 mV,测量结果与抛光液流量大小无关。可以实现对常用磁流变抛光液中磁性颗粒体积分数的在线检测,为实现磁流变抛光过程中抛光液成分的稳定控制提供测量基础。