基于NOA73微球与SU-8微柱的微探针制作（英文）

集成紫外固化胶NOA73微球与SU-8微柱制造的亚毫米探针,可以作为关键部件应用于三坐标测量机。NOA73微球通过NOA73对其他溶液的界面张力形成,柱子由深紫外光穿过微球曝光SU-8形成。这种新技术利用甘油补偿NOA73与空气折射率差,使得紫外光透过NOA73微球后保持接近平行。最终得到高深宽比的探针结构,高度超过1 200μm,微柱侧壁与基底呈89°。     

Optimized design and fabrication of nanosecond response electro optic switch based on ultraviolet-curable polymers

A nanosecond response waveguide electro-optic(EO) switch based on ultraviolet(UV) sensitive polymers of Norland optical adhesive(NOA73) and Dispersed Red 1(DR1) doped SU-8(DR1/SU-8) is designed and fabricated. The absorption properties, refractive indexes, and surface morphologies of NOA73 film are characterized. The single-mode transmission condition is computed by the effective index method, and the percentage of optical field distributed in EO layer is optimized to be 93.78 %. By means of spin-coating, thermal evaporation, photolithography, and inductively coupled plasma etching,a Mach–Zehnder inverted-rib waveguide EO switch with micro-strip line electrode is fabricated on a silicon substrate.Scanning electron microscope characterization proves the physic-chemical compatibility between NOA73 cladding and DR1/SU-8 core material. The optical transmission loss of the fabricated switch is measured to be 2.5 d B/cm. The rise time and fall time of switching are 3.199 ns and 2.559 ns, respectively. These results indicate that the inverted-rib waveguide based on UV-curable polymers can effectively reduce the optical transmission loss and improve the time response performance of an EO switch.     

一种可移动超分辨成像系统的制备及其性质研究

基于浸没透镜设计了一种超分辨成像系统,利用SU-8光刻胶和直径为4.87 m的微球实现纳米级别的超分辨成像。介绍微球成像放大率的求解方法,并通过软件模拟了超分辨成像系统的焦距。通过改变SU-8胶的厚度（从3.4 m到0）,系统的放大率也随之改变（放大率从1.6x到2.6x）。实验表明:SU-8胶的厚度对微球放大率有直接影响,通过该系统可以在普通光学显微镜下观察到蓝光光碟条纹。     

基于微球透镜的任选区高分辨光学显微成像新方法研究

提出和发展了基于毛细管-微球组合探针的任选区、 高分辨显微成像新方法. 建立了微球显微成像的物理模型, 利用成像理论,推导出微球成像的放大倍率; 采用3.0, 4.4, 5.6, 7.5, 10.0 μm等不同直径的SiO₂微球, 对未经刻录的DVD光盘进行了微球显微成像实验, 可以观察到DVD光盘的微纳米结构被明显放大且对比度显著提高, 与理论计算结果相符合; 采用毛细管微探针操纵微球的方法, 实现了基于微球透镜阵列的样品微纳米结构的高分辨显微成像; 在此基础上, 进一步将毛细管微探针与微球组合, 制备出毛细管-微球组合型探针, 首次实现了基于微球透镜的样品任意区域高分辨显微成像.     

激光3D纳米打印温度敏感的微球激光器

耳语回廊模式(WGM)微腔具有品质因子高、模式体积小、制作工艺简单多样、同时对周围环境敏感性极高等优点,已被广泛应用于传感和检测.然而,真正的尺寸可控的三维微腔却少有报道.本文报道了一种有源回音壁模式微球腔,由商业光刻胶SU-8作为腔体材料,有机染料罗丹明B作为增益介质.利用飞秒激光双光子聚合,可以得到尺寸精确可控的真三维微球激光器.同时,由于有机染料的特殊发光机理,随着环境温度的变化,染料荧光带飘移,且会与腔体本征模式形成新的共振激发.在一定温度变化范围内(20℃—35℃),微球激光器的主激射峰波长与温度呈类线性相关.研究结果对合理设计具有理想性能的小型化激光器具有积极的启发.     

聚合物自写入光波导的时域有限差分模拟

利用时域有限差分方法,对非线性光学聚合物SU-8环氧树脂在激光作用下,其折射率会升高的过程进行了数值模拟与分析,得到SU-8薄膜与激光作用一定时间之后,其内部折射率的分布。分别对表面是平面及表面带有微透镜的SU-8薄膜进行了模拟。结果表明,利用折射率升高引起的自聚焦效应,可以在SU-8薄膜内自写入波导;写入的波导以自聚焦焦点为分界点,分为锥形波导和柱形波导。写入的波导长度随着与激光作用时间的增加而增长;在与激光相同的作用时间里,表面带有微透镜的SU-8薄膜,与表面是平面的SU-8薄膜相比,锥形波导的旁瓣更收敛,写入的波导长度更长;在微透镜底面半径保持不变以及曝光时间一定时,微透镜冠高与底面半径比例为0.08时比比例为0.24时写入的波导长度要长12.2%,其中锥形波导部分要长19.2%。     

温度不敏感聚合物波导微环光学生化传感器研究

温度敏感性是影响波导微环光学生化传感器性能的重要因素。从微环谐振方程出发分析了微环传感器温度敏感性产生的机理,研究了以SU8-NOA61-SU8三明治结构聚合物衬底代替传统硅衬底,利用衬底的热膨胀效应抵消波导的热光效应,来消除聚合物波导微环光学生化传感器的温度敏感性。采用ANSYS软件对三明治衬底的厚度进行了仿真设计,得到了温度不敏感条件下的衬底厚度参数。对SU8和NOA61旋涂成膜工艺进行了实验研究,得到SU8和NOA61的膜厚控制精度分别为0.07μm@20 r/min和0.34μm@20 r/min。分析得到三明治聚合物衬底波导微环传感器的温度敏感性和探测极限值,达到了带有温控装置的硅衬底聚合物波导微环传感器的性能。     

咪唑功能化聚苯乙烯包覆硅胶微球分离富集——火焰原子吸收光谱法测定痕量银

制备了咪唑功能化聚苯乙烯包覆硅胶微球并用其填充微柱,建立了微柱分离富集--火焰原子吸收光谱法测定痕量银的方法.研究了填充微柱对Ag(I)的吸附性能及影响吸附的因素,用酸性硫脲作洗脱剂,以峰面积检测,测定Ag(I)的线性范围为0.010-0.50μg/mL,相对标准偏差为2.5%(n=3),检出限为0.002μg/mL,灵敏度提高20倍,填充微柱可重复利用.     

多元丙烯酸酯泡沫微球的制备

 利用自行设计的三喷嘴乳粒发生器,实现了多元丙烯酸酯空心泡沫微球的可控连续制备。通过配制内层为水,中间层为多元丙烯酸酯单体溶液,外层为聚乙烯醇溶液的水/油/水乳液,在紫外光照射时,室温条件下成功快速地制备出粒径1.5~4.0 mm的多元丙烯酸酯泡沫微球。利用扫描电镜、X光机等测试手段对微球的形貌、表面特性进行了研究,结果显示：泡沫微球的高聚物骨架的折射率约为1.50,由大量分散的蜂窝微孔组成,蜂窝的直径不超过1 μm;多元丙烯酸酯泡沫微球的成活率高达93%,单分散性较好。     

在纤式回音壁模式微球谐振腔及其传感特性

提出一种在纤式回音壁模式微球谐振腔，并对其温度和折射率传感特性进行研究。首先，分析了不同尺寸的微球腔与光纤结构耦合时的相位匹配情况，以锥形光纤为探针来拾取并移动钛酸钡微球，将其嵌入空心光纤，形成在纤式谐振腔结构，从而在微球中激发回音壁模式，并与空心光纤端面的反射光相互作用，产生法诺共振。实验结果表明，激发的法诺共振峰曲线的斜率高达-99.3 dB/nm。另外，通过实验证明了此结构对温度和折射率均具有较好的传感特性，灵敏度分别为26.8 pm/℃和-244.97 dB/RIU。该谐振腔性能稳定、结构紧凑、加工简单，在纤式的反射结构使其有望在复杂的传感环境中发挥作用。     

Design and analysis of nano-deep corrugated waveguide grating-based dual-resonant filters in visible and infra-red regions

A theoretical analysis of nano-deep corrugated long-period waveguide gratings on a SU-8 polymer-based channel waveguide with NOA61 optical epoxy coated upper- and lower cladding is presented. The transmission spectra of the gratings show strong rejection bands both at visible (at wavelength region of 450?460 nm) and infra-red (at wavelength region of 1530?1540 nm) regions when a grating period of ?68 μm with optimized grating tooth height is considered. Phase-matching graphs are studied to find the relationship between resonance wavelength and grating period. These results show that the grating parameters significantly affect the characteristics of transmission spectra as well as the resonance wavelength of the grating. Long-period waveguide grating-based band pass filter made by use of same polymer materials are also designed and analyzed. These types of waveguide grating-based filters can widely be used for visible and infra-red wavelength sensing applications.     

SU-8光栅结构中的液晶激光特性

设计制作了SU-8光栅结构的染料掺杂手性向列相液晶激光器件,在器件正面和侧面均实现了随机激光辐射。将激光染料PM597、手性剂S-811、向列性液晶TEB30A按一定比例均匀混合,注入反平行摩擦处理的液晶盒中,器件的下基板通过光掩模法刻蚀出周期为15μm的光栅。利用532 nm的Nd∶YAG固体脉冲激光器作为泵浦源,器件的侧面既在580~590 nm范围内出现了多个离散分立的随机激光辐射峰,FWHM约0.19 nm,又在579~585 nm范围内出现独立的两个激光辐射峰,FWHM约0.19 nm;在器件正面获得了584~590 nm范围的随机激光辐射谱,FWHM约0.17 nm。加热器件至61℃,液晶相变为各向同性态,器件侧面仍出现了波长约590.60 nm、FWHM约0.24 nm的激光辐射峰。分析得出,液晶盒中引入SU-8光栅结构后,光子同时在液晶分子间多重散射和SU-8光栅中布拉格反射获得反馈放大,两种机制相辅相成。器件侧面出现的独立激光辐射峰主要由SU-8光栅布拉格反射提供反馈放大形成,而器件侧面和正面的随机激光辐射峰主要由液晶分子间多重散射提供反馈放大形成。     

355nm激光曝光SU-8胶的XPS谱和FT-IR谱研究

SU-8光胶因具有良好的光刻性能,并可获得稳定的高深宽比而在微加工领域得到了广泛的应用。众多研究采用不同的光源对其进行了多种光刻研究,本文应用355nm激光对SU-8胶进行曝光,分别采用XPS谱和FT-IR谱分析了SU-8胶与激光相互作用过程中,355nm激光对SU-8胶的作用以及反应前后主要成分含量、分子结构的变化,初步探讨了SU-8胶中激光曝光能量与透入深度的关系。     

SU-8光刻胶应变分布光学全场检测方法

由于SU-8光刻胶的内应力将会影响高深宽比结构的全金属光栅的制作质量,本文针对近年来SU-8光刻胶应力测量困难的情况,提出了一种基于激光剪切散斑干涉技术的SU-8光刻胶应变分布测量的新方法。该方法通过对被测胶体加载前后两幅干涉图像的处理,直接得到被测胶体结构的全场应变分布情况,由胶体的应变变形数据即可反映出内应力的变化和分布趋势。同时使用ANSYS有限元分析软件对同一被测胶体进行应变仿真模拟研究,获得胶体结构的变形场仿真数据。组建了实验系统,进行了实验验证,结果表明:实际测量变形量约为1.189μm,仿真的最大变形量为1.088μm,测量误差在允许范围内,且测量的形变趋势与仿真模拟结果相一致,表明激光剪切散斑干涉技术可应用于SU-8光刻胶的应变分布全场无损检测。     

Fabrication of a graphene field effect transistor array on microchannels for ethanol sensing

A new approach to the fabrication of back-gated graphene FET (field effect transistor) arrays on microchannels was investigated. Narrow walls fabricated on a substrate with SU-8 (a negative photoresist), with top metal electrodes were pressed onto another silicon/SiO₂ substrate with predeposited graphene pieces such that the electrodes came into contact with graphene pieces and formed the source and drain contact. The SU-8 narrow walls with the top metal layer were fabricated by the conventional lift-off process. The graphene pieces were reduced chemically from graphite oxide. The I_DS changed immediately by more than 17% when the device was exposed to an ethanol atmosphere. The current recovered very well after the ethanol gas was pumped out. The SU-8 microchannels served as gas flow passages that helped the ethanol vapor reach the sensitive region of the device: the graphene channel. This work provides a convenient way of constructing back-gated graphene FETs for sensing applications. This method could potentially be scaled up for mass production.     

Direct removal of SU-8 using focused laser writing

SU-8 photoresist is an important material used in the development of micro-devices [1]. Cross-linked SU-8 structures have been known for their thermal stability and their strong resistance to standard solvent, acid and base. Due to the inert properties of this polymer, it is difficult to further modify or remove SU-8 once it is completely cured. We report an effective process to pattern cured SU-8 photoresist on glass using focused laser beam. Laser fabrication has been an important tool in various fields of research [2]. We made use of this laser cutting method to create interesting and useful two-dimensional SU-8 structures. The shapes and sizes of the structures created can be controlled by varying the power of the laser, angle of incident of the focused laser beam, the relative speed with which the laser beam traverse through the SU-8 film and the magnification of objective lens used. Besides two-dimensional structures, we can also create three-dimensional structures. In this case, we made use of a combination of controlled depth cutting and undercutting where focused laser beam is transmitted through the transparent substrate. Some possible applications of the laser patterned SU-8 film are also demonstrated in this work. PACS 42.62-b; 42.82.Cr; 79.60.Fr; 79.20.Ds; 78.66.-w     

Silanization and antibody immobilization on SU-8

SU-8, an epoxy based negative photoresist, has emerged as a structural material for microfabricated sensors due to its attractive mechanical properties like low Young's modulus and chemical properties like inertness to various chemicals used in microfabrication. It can be used to fabricate MEMS structures of high aspect ratio. However, the use of SU-8 in BioMEMS application has been limited by the fact that immobilization of biomolecules on SU-8 surfaces has not been reported. In this study, the epoxy groups on the SU-8 surface were hydrolyzed in the presence of sulphochromic solution. Following this, the surface was treated with [3-(2-aminoethyl) aminopropyl]-trimethoxysilane (AEAPS). The silanized SU-8 surface was used to incubate human immunoglobulin (HIgG). The immobilization of HIgG was proved by allowing FITC tagged goat anti-human IgG to react with HIgG. This process of antibody immobilization was used to immobilize HIgG on microfabricated SU-8 cantilevers.     

SU-8去胶工艺对电铸Ni材料力学性能的影响（英文）北大核心CSCD

SU-8负胶具有优异的力学性能、抗化学腐蚀性、热稳定性和生物兼容性,在MEMS工艺和器件中得到广泛应用。镍金属具有良好的力学性能和抗腐蚀性,因此常用来制作MEMS器件。在MEMS执行器中,弹性元件常采用电铸镍制作。SU-8经过经曝光显影后形成致密的交联网络结构是一种高分子聚合物,这种聚合物非常稳定,不溶于强酸强碱及常见的有机溶剂,尤其是在电铸金属结构后的SU-8胶的去除更为困难。目前的SU-8去胶技术,按去胶原理可分:机械物理去胶技术和氧化去胶技术。氧化去胶技术可以有效去除SU-8胶,但氧化去胶方法不同程度地损坏电铸金属,使其力学性能与去胶前相比发生显著的变化。因此需要研究去胶对Ni金属弹性模量的影响,从而为执行机构设计提供准确的基本数据。针对目前运用比较普遍的两种去除SU-8胶方式:微波等离子下游化学刻蚀和强碱熔盐浴,分别进行了去胶实验,对去胶前后的电铸Ni金属进行了弹性模量和硬度测试。实验结果表明,电铸镍的杨氏模量在经过微波等离子下游化学刻蚀后下降18%,而经过强碱熔盐浴后下降36%,但硬度下降不明显。     

Integrated SU-8 photonic gas sensors based on PANI polymer devices: Comparison between metrological parameters

In this work, we have designed and developed three families of integrated photonic sensors for ammonia detection. These photonic sensors are integrated onto single-mode TE₀–TM₀ SU-8 polymer planar waveguides and based on a polyaniline (PANI) sensitive polymer material. The first family relies on the deposit of a PANI–polymethyl methacrylate (PMMA) composite sensitive layer on a given SU-8 waveguide. The second family relies on a PMMA passive layer deposited on the SU-8 waveguide before applying the PANI sensitive layer on the PMMA passive layer. The third family takes advantage of a PANI layer deposited by plasma technique directly onto the SU-8 waveguide. The working principle of such sensors is based on the optical intensity modulation induced within the single-mode waveguide owing to the interaction between the evanescent field and the sensitive layer. The sensing proprieties of these integrated photonic sensors to ammonia gas at room temperature were characterized and the comparison between these different families of photonic sensors is presented. Experimental results show that the sensor based on new plasma–PANI as sensitive layer has the better metrological parameters.     

Automatic microcircuit formation based on gold-coated SU-8 microrods via dielectrophoresis

To explore the application of the characteristics of metallic microparticles, alternating current electric trapping of the SU-8 microrods coated with a thin gold layer by the chemical approach is investigated. Positive dielectrophoresis is used to absorb the gold-coated SU-8 microrods at the edge of the parallel electrodes, thereby forming chains to connect the electrodes. This is a fast automatic microcircuit formation process. Moreover, a non-charged molecule is modified on the surface of the gold-coated SU-8 microrod, and the modified microrods are controlled by the alternating electric field to form a number of chains. The different chains between the parallel electrodes consist of various parallel circuits. In order to compare these chains with different electric surfaces, the impedances of the metallic and modified microrods are measured and compared, and the results show that the gold-coated microrods act as pure resistors, while the microrods functionalized by a non-charged molecule behave as good capacitors.