液体环境中的光热微驱动方法与技术研究

提出和发展了适用于液体(水)环境的光热微驱动技术及光热微驱动机构(OTMA).建立了水环境中OTMA膨胀臂在激光照射下的光热膨胀模型,基于有限元分析推导出膨胀臂的温升分布公式,并对长度1080μm、宽度90μm的膨胀臂在4 mW激光照射下的温升分布进行了仿真,理论研究表明了液体环境中光热微驱动技术的可行性.设计与微加工...     

亚微米级液压式微驱动器工作机理及其特性

为了提高精密机床的加工精度,研究了一种新型的液压式微位移驱动器.用有限元方法分析了缸体内部径向压力对液压式微驱动器输出微位移的影响,得到了驱动器结构设计公式,并讨论了其适用范围.建立了液压式微位移驱动器性能测试系统,对其主要性能进行了研究.研究结果表明,该微驱动器具有输出与输入线性度好(相关系数达到0.999 97)、刚度高(1.0×109N/m)、稳定性好和无滞后等优点.该微驱动器分辨力达到0.01μm,能够实现亚微米级进给,在精密加工和精密测量中具有广阔的应用前景.     

同步跟随式电磁悬浮驱动器的力学分析与测试

设计了一种基于磁场同步跟随的多自由度电磁悬浮式微驱动器,该驱动器悬浮单元和驱动单元相互独立,在一个机构中构建了集驱动、测量和控制于一体的磁悬浮微驱动新方法.通过对该驱动器的受力分析,得到了驱动器多自由度运动状态的数学方程.采用电涡流传感器和DSP控制器,建立了该微驱动器的测控系统,实验结果表明,该驱动器具有较强的稳定性与驱动能力,验证了力学分析的正确性.     

超磁致伸缩微振动电驱系统设计与实现

为了实现对超磁致伸缩驱动器的微振动进行实时精密控制,设计大功率程控电驱系统,包括恒流驱动电路和供电电路。首先,对该恒流驱动电路所采用的连续调整型恒流源的原理进行研究。接着阐述该电路的具体设计以及元器件的选型。然后,详细介绍该恒流驱动电路的供电电路所采用的拓扑结构以及具体设计。实验结果表明:该大功率程控电驱系统输入的小电压信号与输出大电流信号的线性度为0.105%,时漂为3 m A/h,频率可达500 Hz,并且驱动超磁致伸缩驱动器实现1 Hz和5 Hz的正弦输出,基本满足了驱动超磁致伸缩微振动的高精度、高稳定性、高集成度的要求。     

大位移自对准光开关微动作器的模拟和制作

报导了一种新型静电驱动扭转梁大位移微机械光开关微动作器的模拟、设计和制作。模拟结果表明，该微动作器的第一模态频率远低于第二模态，镜子的位移由梁的扭转引起。在32．8V的电压驱动下，上电极的前端位移是69．6μm，镜子的有效位移是57μm。测到第一模态频率是500Hz。利用本结构可成功地解决开关速度和大位移的矛盾。这样的位移足够使用Coming OptiFocus Collimating Lensed Fiber来对准，从而获得低插入损耗。     

用透射式光热偏转技术测量光学薄膜的微弱吸收率

建立了一套透射式光热偏转光谱术实验装置,将它应用于光学薄膜微弱吸收率的测量,灵敏度可达10~(-6),实验结果与用激光量热法及横向光热偏转法所得者皆符合良好。     

超精密飞刀切削加工表面中频微波纹产生机理

超精密飞刀切削是一种重要的超精密加工手段,安装大飞刀盘的超精密铣床能够加工大口径超精密光学元件,加工表面具有很高的面形精度和很低的表面粗糙度值.但是加工表面普遍存在中频微波纹（空间周期从100μm到300μm,幅值低于0.1μm）,极大影响了光学元件的使用.超精密铣床的主轴旋转精度对加工工件影响很大,尤其是主轴轴线偏转会使安装在大飞刀盘外缘处的刀具产生很大位移.为此,建立了适用于空气静压轴承支撑的立式主轴角位移欧拉动力学方程,推导出方程解析解,得出主轴运动规律及其对表面中频微波纹的影响,并设计实验进行验证.最终给出了抑制中频微波纹的工程措施.     

直梁结构光栅光调制器的机电特性分析与实验

介绍了直梁光栅光调制器的结构和原理,建立了器件的机电模型．利用能量法和卡式第二定理分析并得到器件的弹性系数;通过静电力与机械回复力的平衡,得到器件的驱动电压．结合器件的实际参数值,计算得到器件的工作电压为10．71V,吸合电压为11．46V．实验测得器件的实际工作电压为10．5V,吸合电压为12．2V,实验结果与理论分析基本一致．在1kHz脉冲电压的驱动下,器件响应的上升时间和下降时间分别为46．59μs和44．77μs;器件的响应频率约为5kHz．结果表明,加工的直梁光栅光调制器具有较低的驱动电压和较高的响应频率,能够满足微投影显示的要求．     

基于近场技术的微纳尺度热物性测量系统空间分辨率增强

传统的脉冲激光时域热反射系统通常基于远场光学设计,对于微纳米材料热物性测量的空间分辨率约在3μm～10μm范围,不足以满足先进微电子器件和芯片的热物性测试要求.基于近场光学原理,本文研究了提升时域热反射系统空间分辨率的新颖技术方法,并建立了相应的实验系统.实验获得的微纳结构样品测量数据表明,基于近场技术的时域热反射系统...     

一种新型MEMS开关微驱动器研究与仿真

介绍了一种基于光致形变聚合物材料的MEMS开关微驱动器。光致形变聚合物材料在光驱动型微执行器上的应用具有体积小、结构简单、易实现遥控等特点。根据MEMS的尺寸及性能要求建立开关及微驱动器模型,并得到所需最大驱动力。通过计算得出具有一定尺寸光致形变薄膜的等效弯曲行为,并将其应用到MEMS开关微驱动器上。运用ANSYS对微驱动器及闭锁机构仿真分析,根据仿真结果对结构进行改进,确定了采用多层薄板结构的方案,以满足最大驱动力要求。     

Damage threshold determination of bulk polymer samples using pulsed photothermal deflection technique

Photothermal deflection technique was used for determining the laser damage threshold of polymer samples of teflon (PTFE) and nylon. The experiment was conducted using a Q-switched Nd-YAG laser operating at its fundamental wavelength (1-06μm, pulse width 10 nS FWHM) as irradiation source and a He-Ne laser as the probe beam, along with a position sensitive detector. The damage threshold values determined by photothermal deflection method were in good agreement with those determined by other methods.     

Vibration analysis of thermoelastic double porous microbeam subjected to laser pulse

The present work deals with vibration phenomenon of a homogeneous, isotropic thermoelastic double porous microbeam induced by laser pulse heating, in context of Lord–Shulman theory of thermoelasticity with one relaxation time. Laplace transform technique has been used to obtain the expressions for lateral deflection, axial stress, axial displacement, volume fraction field and temperature distribution. The resulting quantities are obtained in the physical domain by applying a numerical inversion technique. Variations of axial displacement, axial stress, lateral deflection, volume fraction field and temperature distribution with axial distance are depicted graphically to show the effects of porosity and laser intensity parameter. Some particular cases are also deduced.     

微细槽的电化学铣削加工

为了研究不锈钢微细槽的电化学铣削加工技术,使用微细的、旋转的圆柱电极作为电化学加工的阴极,采用脉冲电压电化学加工技术用类似铣削加工的方法加工微细槽.研究了脉冲宽度对电极和微细槽侧面加工间隙的影响,并对微细槽铣削加工过程中的电场和流场进行了分析.在相同的电压幅值和平均电压条件下,脉冲宽度越大,侧面加工间隙越大.电场和流场分析表明,微细槽的侧面加工间隙和侧面倾斜度随着脉冲宽度的减小以及进给速度的增加而减小.当脉冲宽度小于工件表面双电层充电时间常数时,采用钝化电解液能够减小电化学杂散腐蚀和微细槽的侧面倾斜度.当脉冲宽度为0.4μs、进给速度为24μm/min时,微细槽的侧面倾斜度很小,侧面加工间隙达到10μm.实验结果表明,采用超短脉冲电化学铣削加工方法和合适的电解液,能够提高微细槽的加工精度.     

基于锆钛酸铅薄膜的变形镜微致动器

以锆钛酸铅（PZT）薄膜作为驱动材料,制备了变形镜的微致动器阵列．使用有限元软件对致动器进行了模拟仿真,得到了驱动器上电极尺寸、Si弹性层厚度等参数对致动器性能的影响,获得了最优化的致动器结构．以钙钛矿相的镍酸镧（LNO）作为PZT薄膜在Pt衬底上生长的缓冲层,增强了PZT薄膜的（100）取向,减小了PZT薄膜的内部应力,提高了致动器的驱动性能．最终制备出的1μm厚PZT薄膜驱动的变形镜微致动器,在10V直流电压的激励下,具有2．0μm的变形量．以PZT薄膜作为驱动材料制备的变形镜微致动器阵列,对变形镜致动器的微型化和系统集成度的提高具有重要意义．     

Gold nanoshell photomodification under a single-nanosecond laser pulse accompanied by color-shifting and bubble formation phenomena

Laser-nanoparticle interaction is crucial for biomedical applications of lasers and nanotechnology to the treatment of cancer or pathogenic microorganisms. We report on the first observation of laser-induced coloring of gold nanoshell solution after a one nanosecond pulse and an unprecedentedly low bubble formation (as the main mechanism of cancer cell killing) threshold at a laser fluence of about 4?mJ?cm(-2), which is safe for normal tissue. Specifically, silica/gold nanoshell (140/15?nm) suspensions were irradiated with a single 4?ns (1064?nm) or 8?ns (900?nm) laser pulse at fluences ranging from 0.1?mJ?cm(-2) to 50?J?cm(-2). Solution red coloring was observed by the naked eye confirmed by blue-shifting of the absorption spectrum maximum from the initial 900?nm for nanoshells to 530?nm for conventional colloidal gold nanospheres. TEM images revealed significant photomodification of nanoparticles including complete fragmentation of gold shells, changes in silica core structure, formation of small 20-30?nm isolated spherical gold nanoparticles, gold nanoshells with central holes, and large and small spherical gold particles attached to a silica core. The time-resolved monitoring of bubble formation phenomena with the photothermal (PT) thermolens technique demonstrated that after application of a single 8?ns pulse at fluences 5-10?mJ?cm(-2) and higher the next pulse did not produce any PT response, indicating a dramatic decrease in absorption because of gold shell modification. We also observed a dependence of the bubble expansion time on the laser energy with unusually very fast PT signal rising (～3.5?ns scale at 0.2?J?cm(-2)). Application of the observed phenomena to medical applications is discussed, including a simple visual color test for laser-nanoparticle interaction.     

Polymer magnetic microactuators fabricated with hot embossing and layer-by-layer nano self-assembly

Polymer-based magnetic microactuators have been fabricated with hot embossing technique and layer-by-layer (LbL) nano self-assembly. Silicon molds are fabricated with conventional UV lithography and wet etching techniques. Hot embossing is used to transfer the patterns from silicon molds to polymethylmethacrylate (PMMA) sheets. The overall processing time for the pattern transfer is less than 20 min. Low-cost devices with massive and rapid replication can be fabricated. Six layers of magnetic iron oxide (Fe2O3) nanoparticles are LbL self-assembled on the PMMA surface as the magnetically sensitive material. Positive photoresist PR1813 is used as the sacrificial layer to protect the gold electrode on the back side of the membrane. LbL nano self-assembly technique provides a simple method to obtain the magnetic film with low cost, short processing time, simple fabrication steps at room temperature. The volume of the magnetic material can be precisely controlled by the number of nano-assembled iron oxide layers. The mechanical, electrical, and magnetic properties of the microactuator are characterized by a laser interferometer. The natural frequency of the actuator is approximately 151 Hz; and the maximum deflection amplitude is about 34 nm. At all frequencies, the increase of the magnetic field increases the deflection amplitude which is in agreement with the theoretical equation.     

Femtosecond Laser Fabrication of Cavity Microball Lens (CMBL) inside a PMMA Substrate for Super‐Wide Angle Imaging

Since microlenses have to date been fabricated primarily by surface manufacturing, they are highly susceptible to surface damage, and their microscale size makes it cumbersome to handle. Thus, cavity lenses are preferred, as they alleviate these difficulties associated with the surface‐manufactured microlenses. Here, it is shown that a high repetition femtosecond laser can effectively fabricate cavity microball lenses (CMBLs) inside a polymethyl methacrylate slice. Optimal CMBL fabrication conditions are determined by examining the pertinent parameters, including the laser processing time, the average irradiation power, and the pulse repetition rates. In addition, a heat diffusion modeling is developed to better understand the formation of the spherical cavity and the slightly compressed affected zone surrounding the cavity. A micro‐telescope consisting of a microscope objective and a CMBL demonstrates a super‐wide field‐of‐view imaging capability. Finally, detailed optical characterizations of CMBLs are elaborated to account for the refractive index variations of the affected zone. The results presented in the current study demonstrate that a femtosecond laser‐fabricated CMBL can be used for robust and super‐wide viewing micro imaging applications.     

高性能被动式微型直接甲醇燃料电池的设计及制作

对一种被动式微型直接甲醇燃料电池进行了设计、制作及测试.利用微模具成型工艺,以ABS为基底材料制作了电池双极端板.采用200 μm厚的不锈钢薄片作为集电极,利用激光切割技术制作进料通道,并在集电极两侧溅射金层以防止电化学腐蚀.有效面积为0.49 cm2的膜电极则采用催化剂覆盖电解质膜的方法制备而成.测试结果表明,室温环境下(25℃)该被动式微型直接甲醇燃料电池在甲醇浓度为6 mol/L时最大功率密度可达22.14 mW/cm2.该性能对于被动式直接甲醇燃料电池的便携式高性能应用具有较大意义.     

Imaging the surface stress and vibration modes of a microcantilever by laser beam deflection microscopy

There is a need for noninvasive techniques for simultaneous imaging of the stress and vibration mode shapes of nanomechanical systems in the fields of scanning probe microscopy, nanomechanical biological and chemical sensors and the semiconductor industry. Here we show a novel technique that combines a scanning laser, the beam deflection method and digital multifrequency excitation and analysis for simultaneous imaging of the static out-of-plane displacement and the shape of five vibration modes of nanomechanical systems. The out-of-plane resolution is at least 100 pm Hz?1/2 and the lateral resolution, which is determined by the laser spot size, is 1-1.5 μm. The capability of the technique is demonstrated by imaging the residual surface stress of a microcantilever together with the shape of the first 22 vibration modes. The vibration behavior is compared with rigorous finite element simulations. The technique is suitable for major improvements in the imaging of liquids, such as higher bandwidth and enhanced spatial resolution.     

Quantum dots as multimodal photoacoustic and photothermal contrast agents

Quantum dots (QDs) have primarily been developed as fluorescent probes with unique optical properties. We herein demonstrate an extension of these QD utilities to photoacoustic (PA) and photothermal (PT) microscopy, using a nanosecond pulse laser excitation (420-900 nm, 8 ns, 10(-3)-10 J/cm(2)). The laser-induced PA, PT and accompanying bubble formation phenomena were studied with an advanced multifunctional microscope, which integrates fluorescence, PA, PT imaging, and PT thermolens modules. It was demonstrated that QDs, in addition to being excellent fluorescent probes, can be used as PA and PT contrast agents and sensitizers, thereby providing an opportunity for multimodal high resolution (300 nm) PA-PT-fluorescent imaging as well as PT therapy. Further improvements for this technology are suggested by increasing the conversion of laser energy in PT, PA, and bubble phenomena in hybrid multilayer QDs that have optimized absorption, thermal, and acoustic properties.