基于双波长像面数字全息显微的微通道检测

针对微流控芯片通道三维形貌的可视化测量需求,搭建了一套反射式离轴双波长像面数字全息显微测量系统。首先,利用分辨率靶和标准样片对系统的横向、纵向分辨率和放大倍数进行标定实验,结果表明双波长全息显微系统在横向宽度及纵向深度测量中具有较好的准确性和可行性。然后,利用该系统分别对由PDMS材料制成的直通道、圆形小室结构微流控芯片以及硅基底微流控芯片通道进行三维形貌检测,并得到定量结果：直通道结构深度为48.6μm,宽度为75.8μm;圆形小室微通道深度为48.5μm,宽度为76.6μm;硅基底微流控芯片测量得到通道深度为61.6μm。上述结果与白光干涉仪的测量结果具有良好的一致性,说明双波长全息显微系统具有较高的可靠性和准确性,可为微流控芯片微通道检测提供新的成像检测方法。     

微流控技术

在今年美国物理学会在德克萨斯奥斯汀召开的“MarchMeeting”上 ,微流控技术是一个热门话题 .微流控技术主要是研究一些中介流体 (即生物组织中处于溶液中的细胞、蛋白质、染色体等 )以模式芯片为平台 ,在电压、热能以及蠕动压差的趋动下在微通道中的流动性能 .在本次会议的报告中最出色的有三个工作 .一个是美国加州理工学院Hansen教授的工作 ,他们研制出了具有最大集成程度的芯片 ,即在一块芯片上有 10 0 0 2 5 0pL并带有控制开关的小空腔 ,能对流体的流动与混合起调节与控制作用 .同时他们还完成了能精确测量反应物剂量的装置 ,其目的…     

微流控SERS芯片及其生物传感应用

由于微流控芯片具有优异的集成性和灵活的可操作性,基于芯片上的检测方法被大量开发,发展十分迅速。其中,表面增强拉曼光谱（SERS）凭借其超高的灵敏度、独一无二的指纹谱和窄峰宽等特点成为一种广泛采用的检测手段。SERS微流控芯片集SERS检测技术与微流控芯片的优势于一体,一方面为SERS检测方法的重复性和可靠性提供了一个高效平台,另一方面推动了微流控芯片的功能拓展,在生物分子探测、细胞捕获乃至组织模拟等领域具有广阔的应用前景。本文在简要介绍SERS的原理及其生物传感应用的基础上,重点概述了SERS微流控芯片的构建及其在生物传感及检测中的应用,最后探讨了该研究方向存在的问题及发展方向。     

基于分水岭算法的电润湿特性研究

采用一种改进的分水岭变换算法研究导电液滴在微流控芯片表面介质上电润湿效应,获得了一个单像素宽度、连续的液滴边缘轮廓,得到了导电液滴在芯片表面的接触角随外加电势的变化规律,进而计算了导电液体的表面张力。相关结论为新型微流控光学变焦透镜阵列器件的设计和研制提供了依据。     

微流控SERS及其在生物医学应用的研究进展

微流控芯片以其对微量样品的精确操控能力而引起特别关注,表面增强拉曼光谱(SERS)作为一种超灵敏的光谱检测技术近年来在痕量检测上应用广泛。微流控芯片与SERS相结合的系统可对微量生物样品进行无损、快速、高灵敏度且高通量的检测分析,在生物医学领域有巨大的应用潜力,是当前的研究热点之一。本文介绍了微流控SERS系统近年的发展情况,包括微流控芯片的制作加工和流体操控,以及微流控芯片中SERS基底的集成;并重点介绍了近年来SERS微流控芯片系统在生物医学上的应用,如生物分子的检测、细胞分析、药物监测和筛选、疾病诊断,以及在环境和食品健康安全方面的检测应用。     

温差驱动微通道内液滴迁移特性数值模拟研究

液滴微流控芯片是以液滴作为基本操作单元的微流控芯片,为实现其应用,需要对其中的液滴进行相应操控。利用温度场可以实现对液滴的迁移、聚合等方面的操控。本文针对温度场操控液滴迁移,采用VOF方法研究温差驱动微通道内液滴迁移特性,并探究温差、液滴尺寸以及液滴类型对液滴迁移特性的影响。研究结果能为温度场驱动的液滴微流控应用提供理论指导。     

ITO表面粗化提高GaN基LED芯片出光效率

使用现有生产线上工艺成熟且成本低廉的技术实现ITO粗化以提高GaN基LED蓝光芯片的出光效率是产业界重要的研究课题。本文通过普通光刻技术和湿法腐蚀技术,实现ITO表面粗化,有效地提高了LED芯片的输出光功率。输入电流为20 mA时,ITO层制备密集分布的三角周期圆孔阵列后,芯片输出光功率提升11.4%,但正向电压升高0.178 V;微结构优化设计后,芯片输出光功率提升8.2%,正向电压仅升高0.044 V。小电流注入时,密集分布的三角周期圆孔阵列有利于获得较高的输出光功率。大电流注入时,这种结构将导致电流拥挤,芯片的电光转化效率衰减严重。经过优化设计后的微结构阵列器件,具有较高的电注入效率,因此芯片的出光效率较高且随输入电流的增加而衰减的趋势较慢,因此更适合大电流下工作。     

银纳米粒子的SERS效应和SEF效应在微流控芯片光学检测中的应用

银纳米离子的SERS技术和SEF技术的信号检测灵敏度非常高,可以用在微流控芯片的定量分析中。为了提高微流控芯片光学检测技术的检测精度,提出一种在微通道中添加银纳米粒子来增强SYBR GreenⅠ拉曼和荧光信号的方法,并对该方法的原理和增强效果进行了研究。首先,利用准分子激光器在PMMA基板上直写刻蚀出宽200 μm、深68 μm的微通道,接着将制备的银前体溶液加入微通道,通过加热制备出表面增强拉曼（SERS）和表面增强荧光（SEF）基板,接下来对添加银纳米粒子前后的拉曼和荧光信号分别进行对比,进一步研究了微通道中不同浓度银纳米粒子对SYBR GREEN I的拉曼和荧光信号增强效果。添加银纳米粒子后,表面增强拉曼（SERS）实验的增强因子为3.5×10³,添加银纳米粒子的样品的荧光信号强度与不含银纳米粒子样品的荧光信号强度相比,约增加了1倍。结果表明,在微通道中检测SYBR Green I时通过增加银纳米粒子显著地增强了拉曼和荧光信号,这种方法可以用在以SYBR GreenⅠ做染料的微流控芯片检测技术中。     

“声表面波信道化滤波器组件”通过鉴定

由中国科学院声学研究所承担的院“八五”军工项目“声表面波信道化滤波器组件”于1996年12月在北京通过了中国科学院组织的鉴定．在现代战争中，电子对抗是一个重要的方面军．电子侦察信道化接收机是所有电子对抗系统的关键．声表面波信道化滤波器组件是由多个声表面波滤波器加上匹配网络组合起来的，有一个输人端和多个输出端．输出信号按频率分路，是信道化接收机中实现信道化功能的关键部件．声学所承担院句＼五”军工项目．研制成频率范围分别为200－350MHZ和350一5O0MHZ两种15信道的声表面波滤波器组件．配套使用时复盖带宽达到300MHZ．在研制过程中，技术上有以下突破：（）采用YllZ”LITaO；基片     

仿生微流控的发展与应用

仿生微流控技术将仿生结构设计应用到微流体装置中,具有很强的学科交叉性.本文提出了通过仿生手段突破微流控的技术瓶颈,从而提高微流控器件的抗污染性能,告别单一功能的微流控系统应用的局限性,实现微尺度下通道的智能化及动态环境变化下的高适应性等.本文提出了仿生微流控的概念,重点介绍了仿生微流控在器件抗污染、器件智能化、生物学和医药方面的最新研究进展,从仿生设计导入应用前景,并探讨了所涉及的物理问题和关键技术,以期为智能微流控芯片的设计开发和应用提供新思路,并为软物质的开发应用、多功能型智能化仿生器件的设计、制备及应用提供参考.     

High-frequency single-electron transport in a quasi-one-dimensional GaAs channel induced by surface acoustic waves

We report on an experimental investigation of the direct current induced by transmitting a surface acoustic wave (SAW) with frequency 2.7 GHz through a quasi-one-dimensional (1D) channel defined in a GaAs - AlGaAs heterostructure by a split gate, when the SAW wavelength was approximately equal to the channel length. At low SAW power levels the current reveals oscillatory behaviour as a function of the gate voltage with maxima between the plateaux of quantized 1D conductance. At high SAW power levels, an acoustoelectric current was observed at gate voltages beyond pinch-off. In this region the current displays a step-like behaviour as a function of the gate voltage (or of the SAW power) with the magnitude corresponding to the transfer of one electron per SAW cycle. We interpret this as due to trapping of electrons in the moving SAW-induced potential minima with the number of electrons in each minimum being controlled by the electron - electron interactions. As the number of electrons is reduced, the classical Coulomb charging energy becomes the Mott - Hubbard gap between two electrons and finally the system becomes a sliding Mott insulator with one electron in each well.     

Rapid concentration of particle and bioparticle suspension based on surface acoustic wave

A method of rapid particle concentration in a droplet has been developed using surface acoustic wave (SAW) technology. A droplet was partially placed on a surface acoustic wave propagation path, and particles were concentrated at the center of the droplet due to the asymmetry. The device consists of two IDTs and two reflectors. The one IDT is used for generating SAW and the opposite IDT is used for detecting output voltage signal amplitude, and then for calculating acoustic power density of a droplet. To investigate concentration effect of the device, starch suspension and rabbit blood cells were used in this paper. Different acoustic power density was applied ranging from 6.13 mw mm⁻² to 210.9 mw mm⁻². The concentration process occurs within 15 s under appropriate acoustic power density put on the droplet, which is much faster than currently available particle concentration mechanisms, and the method is also efficient, which concentrating the particles into an aggregate about one-fifth the size of the original droplet. Additional, the concentration process is no damage to bioparticles. This concentration method can improve greatly SAW biosensor system sensitivity.     

准一维电子通道中声电电流的理论计算

表面声波在GaAs/Al _x Ga_1-x As异质结表面上沿由分裂门产生的准一维电子通道方向传 播时，在通道中诱导产生声电电流.采用WKB近似，计算了只有一个电子被量子阱俘获时的声电电流；并在此基础上，详细讨论了表面声波的频率和功率，以及门电压和源漏偏压对声电电流的影响. 关键词： 表面声波 准一维电子通道 量子阱 声电电流     

State-of-the-art surface acoustic wave linear motor and its future applications

Two merits of the surface acoustic wave (SAW) device are its high energy density and small size. However, the driving frequency is around 10 MHz or higher. In spite of the difficulties involved with high frequency, the high energy density is attractive for actuator applications. The SAW linear motor's no load speed and maximum output force were 1.1 m/s and 3.5 N using a silicon slider. The silicon slider dimensions were 4 x 4 x 0.3 mm3. We made a lot of 30 microns diameter projections on the silicon surface. The acceleration was 1000 m/s2. The SAW motor is expected to be a high speed, quick response, high resolution microactuator, and much more. High driving voltage was a problem. Our newly designed electrode proved that the driving voltage was reduced to less than 10 V to excite the traveling wave. For actual applications, the SAW device will be placed in a slider. This design is effective in terms of performance and cost. The nanotribology of the SAW motor is also an important and interesting subject.     

新型声表面波电流传感器*

将声表面波技术的快速响应特点与磁致伸缩薄膜的高磁敏特点相结合,可实现一种快速、高灵敏、稳定可靠的新型电流检测技术。传感器由双通道差分式振荡器与沉积在传感通道器件表面的声传播路径上的磁致伸缩薄膜组成。该文基于分层介质中声传播理论及磁致伸缩效应,对声表面波电流传感机理进行了分析,以实现对传感器结构的优化设计。实验研制了采用铁钴(FeCo)薄膜的声表面波电流传感器,测试结果表明,该传感器具有快速响应和高灵敏特点。为抑制磁致伸缩薄膜自身的剩磁效应所带来的高磁滞误差,采用的有效途径是将沉积的磁致伸缩薄膜进行图形化设计。实验结果表明,采用栅阵化FeCo薄膜结构的传感器表现出更高检测灵敏度、更好线性及更低的磁滞误差。     

磁致伸缩/压电层叠复合材料磁电效应分析

采用有限元分析软件COMSOL5.0建立了三维悬臂梁模型,分析了磁致伸缩/压电/磁致伸缩叠层复合材料的磁电系数α_(ME),并就几何参数对复合结构磁电系数的影响进行了优化分析.首先,利用稳态求解器研究了磁电层状复合结构内部的应力、应变、位移以及电势分布情况,利用瞬态求解分析了磁电复合结构各变量动态分布规律;其次,应用小信号频域分析研究了该结构的谐振频率以及在不同偏置磁场对输出电压的影响,结果表明,随着直流偏置磁场的增加,输出电压逐渐减小.改变复合材料不同层的厚度,分析了磁电层与压电层厚度比t_m/t_p对磁电系数的影响,结果表明,随着厚度比增加,α_(ME)逐渐增大,其增加速率逐渐减小;最后,分析了磁电系数α_(ME)随复合结构面积、长宽比的变化情况.分析表明,α_(ME)随磁电复合结构面积的增加逐渐增加,其增加速率逐渐减小;当磁电复合结构面积恒定时,其磁电系数随长宽比L/W增加表现出先增加后减小的趋势,存在最优值.     

Transparent ZnO/glass surface acoustic wave based high performance ultraviolet light sensors

Surface acoustic wave(SAW) resonators are a type of ultraviolet(UV) light sensors with high sensitivity, and they have been extensively studied. Transparent SAW devices are very useful and can be developed into various sensors and microfluidics for sensing/monitoring and lab-on-chip applications. We report the fabrication of high sensitivity SAW UV sensors based on piezoelectric(PE) ZnO thin films deposited on glass substrates. The sensors were fabricated and their performances against the post-deposition annealing condition were investigated. It was found that the UV-light sensitivity is improved by more than one order of magnitude after annealing. The frequency response increases significantly and the response becomes much faster. The optimized devices also show a small temperature coefficient of frequency and excellent repeatability and stability, demonstrating its potential for UV-light sensing application.     

Visualization of surface acoustic wave scattering by dislocations

Stroboscopic X-ray topography at the synchrotron beam line was used to visualize the propagation of a 580 MHz surface acoustic waves (SAW) in LiNbO3 crystals. For this purpose, the X-ray bursts coming from the synchrotron storage ring with periodicity of 5.68 MHz were synchronized with the SAW frequency in a phase-locked mode. This method allowed us to "stop" the SAW in time and to observe the X-ray diffraction contrast caused by the dynamic deformation field of SAW. The X-ray topographic images showed well-resolved individual acoustic wave fronts of 6 microm SAW as well as their distortions due to SAW scattering by linear dislocations. Some of the images revealed an exceptional contrast of the concentric rings about the dislocation line, which is caused by coherent interaction of the secondary elastic waves. This contrast is similar to the Fresnel zones in optics, and this conclusion is confirmed by direct summation of secondary waves emitted by local elements of a vibrating dislocation string.     

Spatial confinement of ultrasonic force fields in microfluidic channels

We demonstrate and investigate multiple localized ultrasonic manipulation functions in series in microfluidic chips. The manipulation functions are based on spatially separated and confined ultrasonic primary radiation force fields, obtained by local matching of the resonance condition of the microfluidic channel. The channel segments are remotely actuated by the use of frequency-specific external transducers with refracting wedges placed on top of the chips. The force field in each channel segment is characterized by the use of micrometer-resolution particle image velocimetry (micro-PIV). The confinement of the ultrasonic fields during single- or dual-segment actuation, as well as the cross-talk between two adjacent fields, is characterized and quantified. Our results show that the field confinement typically scales with the acoustic wavelength, and that the cross-talk is insignificant between adjacent fields. The goal is to define design strategies for implementing several spatially separated ultrasonic manipulation functions in series for use in advanced particle or cell handling and processing applications. One such proof-of-concept application is demonstrated, where flow-through-mode operation of a chip with flow splitting elements is used for two-dimensional pre-alignment and addressable merging of particle tracks.     

Novel method for photovoltaic energy conversion using surface acoustic waves in piezoelectric semiconductors

This paper presents a novel principle for photovoltaic (PV) energy conversion using surface acoustic waves (SAWs) in piezoelectric semiconductors. A SAW produces a periodically modulated electric potential, which spatially segregates photoexcited electrons and holes to the maxima and minima of the SAW potential. The moving SAW collectively transports the carriers with the speed of sound to the electrodes made of different materials, which extract electrons and holes separately and generate dc output. The proposed active design is expected to have higher efficiency than passive designs of the existing PV devices and to produce enough energy to sustain the SAW.