LIGA技术及其在制造可动微结构件中的应用

介绍了将LIGA技术及其与牺牲层技术相结合 ,制造可动微结构的工艺方法。并给出了可实现摆动、转动的可动微结构———微执行器、微传感器和三维加速度传感器的制造过程等应用实例     

一种新的纸基微流开关及其活跃方法

提出了一种新的、基于声表面波的纸基微流开关。通过软光刻技术制作内含两个微孔的聚二甲基硅氧烷(PDMS)微架,其上固定经折叠、长度可变的纸通道。PDMS微架贴附于压电基片之上,并在待连接的两微通道之下方,折叠纸通道最低端离压电基片间距为2 mm。压电基片上采用微电子工艺光刻一对叉指换能器和反射栅。当足够强度的电信号加到叉指换能器对时,激发两相向声表面波,使得压电基片上微流体输运到折叠纸通道,改变其长度,连接其上待连通的两纸基微通道,完成开关功能。对可编程微流器件提供了一种新的编程和开关控制方法。     

基于CNTs/PDMS介电层的柔性压力传感特性研究

提出一种基于MEMS工艺的柔性压力传感器制备方法.采用MEMS工艺制备柔性压力传感器模板,结合纳米压印技术、射频磁控溅射技术和PDMS软光刻工艺在PDMS柔性基底上制备了具有"V"型阵列微结构的Ag薄膜平行板电极,基于碳纳米管(CNTs)/PDMS聚合物的压电容特性,制备出电容式柔性压力传感器.针对不同尺寸的压力传感器进行对比测试,本文制作的压力传感器的灵敏度能够达到3.98% kPa-1,具有良好的重复性,在智能穿戴和电子皮肤等方面有着广阔的应用前景.     

用软刻蚀制备组织工程3D聚合物微结构

软刻蚀制备组织工程3D可生物降解、生物相容性好的几何图案聚合物微结构,方法简单,使用聚二甲基硅氧烷(PDMS)作为弹性铸膜.高分辨率透明掩膜图案用CorelDraw软件绘制并用高分辨率行式打印在塑料片上.制备微结构的聚合物材料为摩尔比85/15的聚乳酸/乙醇酸(PLGA)共聚物,对其进行预处理使之具有适当的硬度和柔韧性.用铸造、旋涂两种成模方法制备形体尺寸为10～100 μm的PLGA肢手架.对影响肢手架结构完整及横向分辨率的因素进行了讨论和优化,并对两种成型方法的横向、纵向分辨率进行了比较.作为脚手架在组织工程上应用的概念验证,用热层压方法制造用于细胞培养的多层聚合物结构.实验结果表明,软刻蚀技术提供了一种实现组织工程微尺度3D聚合物结构的有效工具.     

应用于电磁驱动器的非线性平面微弹簧及其集成制造工艺研究

平面微弹簧是MEMS器件(如微驱动器、开关等)中一种常用的微结构。目前,平面非线性微弹簧的设计、制造与应用正日益成为关注的焦点。本文针对微机械电磁驱动器的需求,研制了一种变形量在100 μm左右,弹性变形力在5 mN附近的非线性变刚度微弹簧。研究包括通过仿真分析确定了弹簧的结构方案和影响因素,提出了配套的原位集成制造微加工工艺,并测试了所研制“V型”平面微弹簧的非线性特性,验证了所提出方案的可行性。为非线性弹簧的进一步设计和应用提供参考。     

电子束光刻三维微结构的模拟仿真

利用电子束光刻技术,在正性光阻上加工三维微结构。为了模拟预测微结构的表面轮廓,需要建立电子束光刻模型。通常有两种方法建立能量沉积模型,获得能量密度分布函数,分别是随机函数方法和近似函数方法。对能量密度分布函数作线性处理,设计加工三维微结构。借助Monte Carlo和元胞自动机综合算法模拟电子束光刻的加工过程,模拟结果与实验结果在很大程度上相一致,说明电子束光刻模型的建立和对能量密度分布函数的线性处理过程是合理的。     

用于软光刻的恒温实验台的设计

介绍了一种可用于软光刻操作的恒温实验台的设计与实现.在一个密闭的小型箱体中集成了温度与压力控制、照明及紫外光照、操作手套等组件,可以实现无尘、恒温、压力可控、紫外光照等多种功能.在该恒温实验台中,利用聚二甲基硅氧烷进行微传递模塑实验研究,考察了温度、压力等对聚二甲基硅氧烷成模特性的影响.同时,还利用聚二甲基硅氧烷与聚亚胺脂的两次复制完成了硅微芯片结构向玻璃基底的转移.研究结果表明:这一新的实验研究平台可以实现恒温、无尘操作、一定的真空度以及紫外照射,满足普通实验室进行微传递模塑等软光刻操作的要求.     

本期摘要

电子束光刻三维微结构的模拟仿真 注：江苏省前瞻性联合研究项目（No．BY2015070-06） 作者：鲍先同,幸研 单位：东南大学,江苏南京211189 摘要：利用电子束光刻技术,在正性光阻上加工三维微结构。为了模拟预测微结构的表面轮廓,需要建立电子束光刻模型。通常有两种方法建立能量沉积模型,获得能量密度分布函数,分别是随机函数方法和近似函数方法。对能量密度分布函数作线性处理,设计加工三维微结构。     

圆形振动膜硅微电容传声器

硅微传声器是一种用MEMS技术制造的、将声信号转换为电信号的声学传感器.该传声器只需五次光刻工艺即可制作完成,其灵敏度在偏置电压为9V时可达15mV/Pa左右,在100Hz～18kHz的范围内的频率响应也较平坦.     

微机电系统(MEMS)技术的应用:微结构气敏传感器

硅和硅基微机电系统技术是微机电系统技术的主流,本文主要介绍用这种技术制造的各种微结构气敏传感器。     

Micropatterning of sulfonated polyaniline using a soft lithography based lift-off process

A combination of soft lithography and lift-off processing is presented for the fabrication of sulfonated polyaniline (SPAN) microstructures. A soft lithography based micromolding process was used to pattern sacrificial layers using a thermoplastic polymer. SPAN was then polymerized in situ to coat the patterned substrate. The sacrificial layer was removed by lift-off in an organic solvent, leaving the patterned SPAN on the substrate. This process was performed on several rigid and flexible substrates including glass, silicon, and polyimide. The film thickness and roughness were measured as a function of reaction time using atomic force microscopy. Patterns were also imaged using scanning electron microscopy. This process provides a cost effective and versatile method of patterning SPAN and has potential applications in a number of conducting polymer devices.     

Fabrication of Fresnel zone plates with high aspect ratio by soft X-ray lithography

High focusing efficiency Fresnel zone plates for hard X-ray imaging is fabricated by electron beam lithography, soft X-ray lithography, and gold electroplating techniques. Using the electron beam lithography, Fresnel zone plates which has an outermost zone width of 100 nm and thickness of 250 nm has been fabricated. Fresnel zone plates with outermost zone width of 150 nm and thickness of 660 nm has been fabricated by using soft X-ray lithography.     

Micropatterning PEDOT:PSS layers

PEDOT:PSS is a conductive polymer that is used as electrodes in organic electronic devices, but also in neuronal probes and implantable devices. This material can also be used for building deformable electrodes in soft substrates for several sensing applications. However, this material being sensitive to several chemicals and moisture it is difficult to pattern microstructures using standard lithography techniques. This paper will review and show some techniques developed for patterning PEDOT:PSS thin films using both soft lithography, such as microcontact printing and shadow masking, and conventional lithography techniques. In addition of this review we present a new lithography technique using silicon nitride protection layer and an analysis and comparison of ICP RIE dry plasma etch rates of PEDOT:PSS with different gases.     

Soft lithography based on photolithography and two-photon polymerization

Over the past decades, soft lithography has greatly facilitated the development of microfluidics due to its simplicity and cost-effectiveness. Besides, numerous fabrication techniques such as multi-layer photolithography, stereolithography and other methods have been developed to fabricate moulds with complex 3D structures nowadays. But these methods are usually not beneficial for microfluidic applications either because of low resolution or sophisticated fabrication procedures. Besides, high-resolution methods such as two-photon lithography, electron-beam lithography, and focused ion beam are often restricted by fabrication speed and total fabricated volume. Nonetheless, the region of interest in typical microfluidic devices is usually very small while the rest of the structure does not require complex 3D fabrication methods. Herein, conventional photolithography and two-photon polymerization are combined for the first time to form a simple hybrid approach in fabricating master moulds for soft lithography. It not only benefits from convenience of photolithography, but also gives rise to complex 3D structures with high resolution based on two-photon polymerization. In this paper, various tests have been conducted to further study its performance, and a passive micromixer has been created as a demonstration for microfluidic applications.     

Magnetic lithography for servowriting applications using flexible magnetic masks nanofabricated on plastic substrates

Magnetic lithography (ML) is a process qualitatively analogous to contact optical lithography which transfers information from a nanopatterned magnetic mask (analog of optical photomask) to magnetic media (analog of photoresist), and is interesting for applications in instantaneous parallel magnetic recording, in particular for servowriting applications. The magnetic mask consists of nanopatterned magnetically soft material (FeNiCo, FeCo) on a thin flexible plastic substrate, typically Polyethylene teraphtalate (PET) or polyimide. When uniformly magnetized media is brought into intimate contact with the magnetic mask, an externally applied magnetic field selectively changes the magnetic orientation in the areas not covered with the soft magnetic material. Flexible substrate of the magnetic mask offers superior compliance to magnetic media which is likely to have imperfect flatness and surface particulate contamination. We discuss nanofabrication challenges of magnetic masks on plastic substrates, including electron beam lithography, electroplating and lift-off processing on the nanometer scale, adhesion of metal thin films on PET and polyimide substrates, and release of plastic films from rigid substrates used during the processing. We present results on fabricated magnetic masks, magnetic force microscopy images of the magnetic transition patterns and disk spinstand tests of servowritten patterns.     

阵列型微拓扑结构基底的制备及其对神经细胞电生物物理特性的影响

以紫外光光刻、硅蚀刻及软光刻技术制备了微柱阵列型细胞培养基底.实验发现,在4μm的结构高度下,当微柱特征尺寸大于或等于4 μm时,该法能制备结构规整清晰的聚二甲基硅氧烷微柱阵列型基底.特征尺寸为2μm的基底已经接近该法的极限加工能力,所加工的微柱阵列出现倒伏或缺失.采用一种简单的倾斜角法可以制备一种聚苯乙烯微球致密阵列...     

Design and fabrication of 3-dimensional helical structures in polydimethylsiloxane for flow control applications

Soft lithography in 2-dimensional (2-D) was developed for polymer MEMS applications about two decades back. The technique was highly useful for replication of microstructure molds using a soft polymeric material called PDMS (polydimethylsiloxane). From its inception the process has been widely applied to microfluidics, biochips, hybrid biomedical microdevices etc. However, it was limited to only surface microstructures and 3-Dimensional (3-D) soft lithography although performed by some research groups involved some very precise and expensive techniques like stereolithography etc. The exploration of soft lithography in three dimensions by using a replication technique with copper wires with micron size diameters was performed by our group relatively recently (Singh et al. in International conference on MEMS, IIT Madras, Chennai, 2009). In this work we have used the 3-D replication and molding technique to develop concentric solenoid patterns around micro-channels in the bulk of PDMS. The solenoidal paths of various pitches ranging from 0.4 to 1.2 mm have been replicated in PDMS using an innovatively designed fixture. The solenoids have been structurally characterized using an inverted fluorescence microscope (Nikon 80i) for dimensional parameters like pitch, length etc. Further, the solenoidal path designs have been simulated, optimized and fabricated around a central channel of 80 μ diameter and we have observed the repeatability of this fabrication process multiple times. The purpose of this architecture is to initiate valving action wherein fluid movement in the central channel can be restricted by filling the surrounding solenoidal track with compressed air at high pressure so that it can squeeze the centrally located micro-channel carrying the liquid. This valving structure may find a lot of applications in lab on chip devices, PCR biochips, biomedical micro-devices etc.     

Development of high aspect ratio X-ray parabolic compound refractive lens at Indus-2 using X-ray lithography

A synchrotron beamline dedicated to soft and deep X-ray lithography is operational on Indus-2 synchrotron source and is being used for high aspect ratio microfabrication. This X-ray lithography facility provides the access to X-ray mask fabrication, X-ray exposures and development of micro-nano structures. We report the development of planar parabolic refractive X-ray lenses in SU-8 for energy range 8–20 keV using this facility. The focussing properties of X-ray lenses were studied with synchrotron radiation in the X-ray energy range 8–20 keV on the moderate emittance machine Indus-2. A focal spot of 11 μm at 15.9 keV is obtained with a gain of 18.     

Structure quality in deep X-ray lithography applying commercial polyimide-based masks

The structure quality of deep X-ray lithography components strongly depends on the quality of the applied X-ray mask. In this article we compare the results obtained with two different mask types. Sophisticated working masks generated by e-beam lithography, soft X-ray lithography and electroplating of gold absorbers on a titanium mask membrane have been fabricated at the Institute for Microstructure Technology, Research Center, Karlsruhe (FZK/IMT), Germany. Prototype masks generated by e-beam lithography, optical lithography and electroplating of gold absorbers on a polyimide mask membrane have been fabricated by Optnics Precision, Japan, with the aim to offer commercially available low cost masks. Both mask types were applied to pattern PMMA resist layers of 300–750 μm thickness at the 2.5 GeV electron storage ring ANKA, Germany, using comparable process parameters. FZK/IMT masks provide microstructures with significantly better structure quality. The layout area, however, is currently limited to 12 cm², and the Ti mask membrane tends to lead to a slight resist surface attack, such as rounding of the resist edges. Optnics masks provide microstructures with reduced structure quality due to sidewall striations (sidewall roughness up to 2 μm) and thermal distortions (of up to 3–5 μm) which limit the potential scope of applications. They could nevertheless potentially be applied as low quality, low cost X-ray masks. High resolution and high accuracy applications, however, require more sophisticated but also more expensive masks, like the Ti-masks from FZK/IMT.     

Microfluidic spatial growth of vertically aligned ZnO nanostructures by soft lithography for antireflective patterning

Hierarchical assemblies of nanostructured building blocks on conducting substrates are significant for construction of functional devices. Microfluidics is powerful but less exploited tool for spatial organization or growth of functionally sophisticated nanostructures with precise control. In this paper, we introduce a simple but unique strategy for the hydrothermal synthesis and patterned assembly of ZnO nanostructures within microchannels by soft lithography technique. Optical/antireflection properties of such hierarchically structured nanostructures are studied.