基于单片机的DDS多波形发生器的设计

本文采用直接数字式频率合成技术DDS,以AD9852、AD9833芯片为核心,由单片机控制,设计了一种结构简单性能优良的波形发生器,可输出正、余弦波,方波、三角波等.该波形发生器具有频率分辨率高,频率切换快,频带宽及全数字化易于集成等诸多优点,应用范围十分广泛.     

基于纳米磁珠技术的新型微全分析DNA芯片的研究

在微全分析系统的研究中,样品提取及DNA分析技术是非常重要的一个环节.也是目前国内外研究的热点之一.文中介绍了一种新型的基于单芯片的样品制备和扩增方法.采用多层微加工技术制作SU-8模具,通过注模成型,制作出有立体微柱结构的PDMS(聚二甲基硅氧烷)芯片,在芯片微池内填充超顺磁性磁珠,利用固相提取(solid phase extraction,SPE)法,将细胞裂解、DNA提取、PCR反应等功能集成在一个PDMS芯片上.整个流程快速有效,操作简便且易于芯片系统集成,提取产物可以不必洗脱,直接作为下一步PCR反应的模板,在同一芯片上进行扩增反应,实现了样品预处理、DNA提取和PCR扩增的集成.     

基于数字传感芯片的温度脉动仪

温度脉动仪是一种用来测量大气光学湍流强度的仪器。传统的温度脉动仪用微细铂丝作为感温材料,具有响应快速、输出线性、灵敏度高等优点,但是铂丝容易折断且更换较为不便。考虑到基于MEMS工艺的数字式传感芯片的性能稳步提升,且具有成本低廉、易于集成等优点,该文提出用数字式传感芯片替代铂丝来探测温度脉动,开发了数字式温度脉动测量装置原型,进行了多天的外场实验以及与传统脉动仪的对比实验,分析了两种温度数据处理的计算方法。实验结果表明,数字式温度脉动仪可以较好地测量大气折射率结构常数。数字式温度脉动仪作为一种性价比高、简便易用、可快速搭建测量的仪器,可以作为传统温度脉动仪的有益补充。     

普通消解与微波消解分析植物样品中Al等元素的方法比较

采集红壤地区植物样品65个,普通消解和微波消解后用ICP测定A l等6种元素含量。对两种消解结果进行线性回归分析发现,Al、Ca、Fe、Mg、Mn、P的回归系数分别为1.0014、1.0056、1.0725、1.0831、1.0039、0.9915;相关系数分别为0.9988、0.9834、0.9891、0.9970、0.9941、0.9945。两种消解方法对A l的消解具有很强的可比性。微波消解法具有能耗少、试剂利用率高、运行条件一致、样品损失少等优点。     

DSP生成SPWM波的一种设计方法

介绍了TMS320F2407A数字信号处理芯片生成SPWM波,采用等面积算法.先分析了等面积法生成SPWM波算法原理,然后运用TMS320F2407芯片进行波形实现,产生的SPWM波,具有速度快、精度高、对称性好等优点.     

一种频移键控信号的直接数字解码算法

提出一种FSK信号的直接数字解码算法,具有快速、简单、准确可靠、易于用DSP专用芯片实现等优点.本算法已在一种通讯设备上得到了使用,证明了其有效性.     

MC1648在电感测量中的应用

介绍了一种基于MC1648集成振荡芯片的电感测量装置,利用接入不同的电感和电容产生谐振,输出的正弦波信号分频后接入51单片机,通过测量正弦波信号的周期来测得频率,再计算出相应的电感值显示出来。此方法具有精确度高、测量范围大、成本低廉、易于实现等优点。     

集成开关电源控制器MC34063的原理及其应用

MC34063是一种微功耗的新型集成开关电源控制器,利用它可方便地组成各种形式的直流变换电路,而且具有外围元件少,功耗低,体积小和调试方便等优点。本文主要介绍集成开关电源芯片MC34063的原理和应用电路的设计,最后简要地说明该芯片的实际应用线路。     

应用DTMF芯片实现煤矿井下低速数据传送

介绍了ＤＴＭＦ（ＤｕａｌＴｏｎｅＭｕｌｔｉｆｒｅｑｕｅｎｃｙ）芯片及其构成煤矿井下数据传输系统的方法，ＤＴＭＦ芯片是发送和接收双音调信号的专用芯片，具有抗干扰能力强，工作可靠，外围元件少，易于与微机接口，构成系统简便等优点，应用在煤矿井下的低速数据传送上，有其独到的优点。     

基于L9352B的电磁阀控制电路设计与实现

提出了一种基于ARM与集成驱动芯片L9352B的控制方法,该方法通过ARM的输入和输出信号,经隔离后送入集成驱动芯片,对电磁阀进行控制和检测。集成驱动芯片除了可以驱动4通道电感负载外,还可以监测每个通道是否出现诸如短路、开路、过载、过热及时钟丢失等故障。然后对电磁阀的硬件电路进行详细的设计。实际工程应用的结果表明此电路设计可行,具有可靠性高、成本低、驱动能力强、故障监测功能多的优点。     

基于相关检测的光纤倏逝波生物传感器研究

构建了一种以光纤和光纤束作为系统信号传输通道的光纤倏逝波生物传感器系统,根据光纤探针的倏逝波理论和模式匹配理论对光纤探针进行了设计与制作,然后应用直接结合分析的方法对该传感器系统的探测性能进行了实验检测.实验针对光纤探针置于空气中和蒸馏水中两种情况进行,同时将系统检测到的信号通过数据采集卡采集到计算机中,并进行相关检测分析.对光纤探针置于空气中和蒸馏水中两种情况,系统分别获得了16.7和20.5的探测信噪比.实验结果表明,该相关检测方法能很好的区分系统的噪声信号和所探测的荧光信号,整个系统具有良好的可行性.     

Microfluidic platforms for discovery and detection of molecular biomarkers

Microfluidics has emerged as a promising platform for discovery and detection of molecular biomarkers recently. With this approach, the discovery of these biomarkers could be more efficient in time and consumes less samples and reagents. Furthermore, the entire discovery process could be automated since all the functional microfluidic devices such as micropumps and microvalves could be integrated on a single chip. Similarly, the detection of the discovered molecular biomarkers is also promising. Detection of nucleic acid biomarkers, protein biomarkers, and metabolite biomarkers has been demonstrated on microfluidic platforms recently. When compared with their large-scale counterparts, the miniature system can perform the detection of these biomarkers within less analysis time while a multiplexed detection scheme could be easily achieved. Furthermore, the entire detection process could be automated on the single chip as well. This review paper is therefore to review the recent development of microfluidic devices and systems for the discovery and detection of the molecular biomarker. Techniques for biomarker discovery, verification, and detection that have been adapted into microfluidics were first reviewed, and their advantages were highlighted. The new approach of biomarker screening based on in vitro-generated affinity reagents such as nucleic acid aptamers and peptide affinity reagents was then reviewed. Finally, in the biomarker detection section, this review placed a special emphasis on commercialized microfluidic-based diagnostics for molecular biomarkers.     

一种新型本征倏逝波型光纤传感器的研究

研究开发了一种新型本征型光纤倏逝波传感器.采用有机玻璃板和大半圆弧高抛光PVC管构成光纤支架,将60/125 μm阶跃多模光纤隔一定距离剥除等长度涂覆层后缠绕于光纤支架上,其无涂覆层部分位于上下两PVC管之间,经化学腐蚀后获得裸芯总长度大于0.5m的新型高灵敏本征型光纤倏逝波传感器.实验结果表明:该传感器对亚甲基蓝的探...     

便携式血氧信号检测装置设计

实现动态环境下血氧饱和度的实时连续检测,研制了一种基于透射式检测原理的血氧饱和度监测装置.采用透射式光频转换器采集人体光电容积脉搏波,低功耗处理芯片MSP430为主控芯片,获取的脉搏波信号经过程序处理之后,通过蓝牙模块无线发送到终端设备.在动态环境下脉搏波信号存在多种干扰,利用了脉搏波信号的上下包络线信息,采用邻值代替法去除奇异点,低通滤波去除高频干扰,形态学滤波去除基线漂移和运动伪差干扰.该装置具有成本低、功耗低、易操作等特点,实验结果表明:所得到的血氧饱和度具有较好精度,能够动态实时地监测.     

Utilization of nanoparticles in microfluidic systems for optical detection

An increasing interest has been shown in microfluidic systems due to their properties including low consumption of reagents, short analysis time and easy integration. However, despite of these advantages over conventional methods, some limitations in sensitivity and selectivity still exist in microfluidic systems. Recently advancements in nanotechnology offer some new approaches for the detection of target analytes with high sensitivity and selectivity. As a result, it is an appropriate method to enhance the detection sensitivity through a combination between microfluidic system and nanotechnology. Optical detection is a dominant technique in microfluidics because of its noninvasive nature and easy coupling. Numerous studies that integrate optical microfluidic system with nanotechnology have been reported in recent years. Therefore, optical microfluidic systems in combination with nanomaterials (NMs) are reviewed in our work. We illustrate the functions of different NMs in optical microfluidic systems and the efforts of different researchers to improve the performance of devices. After the introduction of different nanoparticle-based optical detection methods, challenges and future directions in the development of nanoparticle-based optical detection schemes in microfluidics have also been discussed.     

基于超声波传感器的液氮流量测控系统

针对液氮冷冻治疗控制困难,本文介绍了一种利用超声波传感器和AT89C52单片机组成的液氮流量测控系统,利用频差法实现对液氮流量检测。文中详细地论述了超声波流量检测原理、系统硬件结构和工作原理。系统结构简单,操作方便,使用安全,性能稳定可靠,能有效地解决液氮冷冻治疗过程中的流量测量和控制问题。     

永磁同步电动机转子位置检测方法

转子位置检测是自控式永磁同步电动机调速控制系统中不可缺少的环节。利用光电开关原理,根据波形分析法求逻辑关系表达式,用复杂可编程逻辑器件实现的光电式转子位置传感器不仅可集成多种运行控制方案,而且还具有实时性好、结构简单、可靠性高、易于实现的优点。     

Acoustically generated flows in microchannel flexural plate wave sensors: Effects of compressibility

Acoustically generated flowfields in flexural plate wave sensors filled with a Newtonian liquid (water) are considered. A computational model based on compressible flow is developed for the sensor with a moving wall for pumping and mixing applications in microchannels. For the compressible flow formulation, an isothermal equation of state for water is employed. The velocity and pressure profiles for different parameters including flexural wall frequency, channel height, amplitude of the wave and wave length are investigated for four microchannel height/length geometries. It is found that the flowfield becomes pseudo-steady after sufficient number of flexural cycles. Both instantaneous and time averaged results show that an evanescent wave is generated in the microchannel. The predicted flows generated by the FPWs are compared with results available in the literature. The proposed device can be exploited to integrate micropumps with complex microfluidic chips improving the portability of micro-total-analysis systems.     

光纤倏逝波生物传感器的结构研究

光纤倏逝波生物传感器的性能主要体现在探测能力和简便性两个方面,为了提高其探测极限和野外适应性,针对光纤探头的倏逝场激发能量和系统结构的整体性进行了较为系统的研究,分析了三种不同发展阶段的系统结构,设计和搭建了一种目前发展的基于光纤束的荧光光纤倏逝波生物传感器系统,以此系统为基础进行了实验检测并取得了较为满意的检测效果.最后给出了下一阶段的系统结构发展方向并分析了其优越性和可行性.     

A Monolithic Dual-Color Total-Internal-Reflection-Based Chip for Highly Sensitive and High-Resolution Dual-Fluorescence Imaging

We report a dual-color total-internal-reflection (TIR)-based chip that can generate two overlapping evanescent fields with different wavelengths for simultaneous imaging of two types of fluorophores. We derived a general relationship among the dimensions of the components of the chip to guarantee the overlap of two evanescent fields. Optical simulation results also confirm the generation and overlap of two evanescent fields. Using Si bulk micromachining and poly(dimethylsiloxane) (PDMS) casting, our fabrication method integrates all miniaturized optical components into one monolithic PDMS chip. Thus, assembly is unnecessary, and misalignment is avoided. Our PDMS chip can be employed with various sample delivery platforms, such as glass slide, flow cell, microchannel, etc. We first demonstrated the capability of the chip by imaging TIR fluorescent spots of a mixture of two fluorophores, namely, fluorescein and tetramethylrhodamine. We then employed the chip to observe the Brownian motion of a mixture of nile-red and dragon-green 500-nm microbeads. Our chip could potentially be integrated into a micro-total analysis system for highly sensitive and high-resolution dual-fluorescence imaging applications.$hfill$[2009-0188]