基于石英和载玻片的微电极制备工艺研究

研究以石英片和载玻片为基底的微电极制备工艺,以较常见的叉指型电极为例,基于光刻工艺中各工艺参数要求,重点研究曝光和显影时间对微电极的影响。制得的2种不同基底的电极,采用对比度、精度等关键参数进行分析,最终确定选用载玻片作为芯片基底并获得其最佳工艺参数;制作带电极的PDMS—玻璃微流控芯片,通过实验,成功观察到酵母菌细胞的正、负介电泳现象。     

利用电子束曝光系统制作高深宽比图形的研究

为了加工具有高深宽比的器件,采用能量连续递减近似模型,运用蒙特卡罗方法分析高能电子束曝光领域的电子散射轨迹及背散射电子对曝光分辨力的影响,探讨了制作高深宽比图形的工艺条件。计算机模拟结果与实验结果吻合得很好,表明在其它实验条件不变的情况下,较高的加速电压能提高图形的高深宽比,提供了制作高深宽比图形的一种方法。     

采用SU—8胶制作模具的工艺研究

主要描述了SU—8胶制造微流体芯片用模具的工艺研究。讨论了各工艺流程主要包括有前烘、中烘、光刻、显影等因素对模具的影响。提出了一个可供参考的模具制作工艺流程,对抗粘层工艺进行了讨论。另外,在模具制造过程中加入反应离子刻蚀(RIE)来提高SU—8与硅基底的粘附性。最终通过上述的工艺研究,成功制作出了应用于流体的模具,并制造成了微流控芯片。     

基于微流控光开关的波导结构分析与优化

光开关是全光网的关键器件,提出一种全新基于微流控技术的波导型光开关设计。通过电控方法改变光波导结构,实现光路变化。基于有限元方法,重点研究了光开关插入损耗、串扰、透过率等参数,对波导层光传输性能进行评价。优化结果表明,当波导层以一定角度斜交叉时,透过率提高,插入损耗降低,最低降到0.18dB,实现了光开关的结构优化。由于采用微流控技术和有机光学材料,这类开关体积小、结构简单、成本低,易于集成大规模光开关阵列。     

基于PVDF薄膜的流场动态压力检测方法的研究

针对检测狭小空间流场压力时,通用液体压力传感器存在体积大、频响低以及干扰流场等问题,提出一种基于聚偏氟乙烯(PVDF)薄膜的流场动态压力检测方法,该方法采用光刻工艺直接在敷镀有金属铝电极的PVDF薄膜上制作压力传感元件,该元件具有面积小、厚度薄、柔韧性好的特点,非常适合于狭小流场空间壁面压力分布的测量.试验研究表明:该...     

基于FPGA的微流控芯片电泳控制系统设计

设计一套基于FPGA的微流控芯片的电泳控制系统。该系统采用具有大量控制端口的FPGA作为系统的控制芯片,同时为了节约控制端口,选取串行控制的A／D与D／A芯片;采用USB2.0高速传输接口与上位机通信,满足了实施控制与数据上传的要求;采用VerilogHDL语言对芯片编程后,可同时对30个PCR芯片实施控制,另外还编写了基于Windows XP的驱动程序与控制软件。     

基于双差压式的液体微流检测仪设计

针对现有液体流量计对低流与微流分辨力不够的难点,设计了一种基于双差压原理的新型液体微流检测仪.在单差压传感器的另一侧,接有完全相同的取压管和差压传感器,当液体流过导液管时,会同时在两侧的输入管与输出管之间产生压力差,形成双差压.双差压传感器将导液管入口与出口之间的压力差转换成电压输出,经放大电路放大后送单片机实现A/D转换和信号处理,最后显示出流量值.测试结果表明:该微流检测仪分辨力达到0.1 mL/min,每个流量点的重复性优于0.042％,具有设计原理新颖、结构简单、精度高、量程范围宽等优点.     

基于MEMS技术的SU-8仿昆虫微扑翼飞行器设计及制作

为研制一种轻质仿昆虫微扑翼飞行器,提出了采用微机电系统(MEMS)领域的SU-8光刻胶作为结构材料的制作方案.基于仿生学原理和微机电系统加工技术,设计微扑翼飞行器结构及MEMS 工艺方法.研究结果表明,该种结构设计及制作方案满足设计要求,为仿昆虫微扑翼飞行器的研制提供了一种很好的途径.     

Reduction of diffraction effect for fabrication of very high aspect ratio microchannels in SU-8 over large area by soft cushion technology

Edge bead due to spin coating has been found to cause an air gap as large as 53 m for a 99-m thick (measured at the wafer center) SU-8 coating over a 4-in. wafer. This caused poor mask width replication and non-uniformity of SU-8 pattern width. We have devised a process using a soft cushion technology to improve mask dimension replication and large-area pattern uniformity. A soft cushion was placed beneath the substrate to produce convex bending of the wafer in order to improve the contact between the mask and photoresist top surface during UV exposure. Dramatic improvements in pattern uniformity, from over 30% variation in SU-8 width across the wafer to less than 10%, and mask width replication, from 54% deviation from mask width to 20%, have been demonstrated. Numerically calculated increases in SU-8 width from the wafer center to the edge bead using the Fresnel diffraction equation match well with observed values. Further, employment of this technique with a narrow (10 m) dark-field mask enabled the fabrication over the entire surface of 4-in. diameter wafers of dense SU-8 gratings separated by microchannels with aspect ratio over 18.     

Process research of high aspect ratio microstructure using SU-8 resist

SU-8 is a negative, epoxy type, near-UV photoresist. This resist has been specifically developed for ultrathick, high-aspect-ratio MEMS-type applications using standard lithography equipment. However, in practice, SU-8 has shown to be very sensitive to process parameter variation. The orthogonal array was used in our experiments in order to improve the lithography quality and analyze the interaction among the parameters. The analyses show that the interaction between the exposure dose and post exposure bake has played an important role in adhesion between SU-8 resist and the substrate. The proposed process conditions are given. The output structure has straight sidewall profile, fine line and good space resolution. The aspect ratio is larger than 20. Moreover, several metallic films are used as substrates. The Ti film with oxidation treatment was found to have the strongest adhesion to the resist. The result will help to open possibilities for low-cost LIGA-type process for MEMS applications.     

Design and fabrication of a SU-8 based electrostatic microactuator

Comb-drive microactuator is widely used in MEMS devices and traditionally is made of silicon as structural material using silicon-based fabrication technology. Recent development in UV lithography of SU-8 has made it possible to fabricate the ultra high aspect ratio microstructures with excellent sidewall quality. In this paper, we report a low cost alternative to the silicon-based comb drive by using cured SU-8 polymer as structural material. The microactuator was designed to have a integrated structure without assembly or bonding. A unique integration fabrication process was successfully developed based on UV lithography of SU-8 and selectively metallizing SU-8 polymer structures. Preliminary experimental results have proved the feasibility of the microactuator and the fabrication technology.     

Fabrication of support structures to prevent SU-8 stiction in high aspect ratio structures

We have previously demonstrated that it is possible to fabricate densely-packed high aspect ratio structures in SU-8 by means of a top-plate support member which stiffens the overall structure and prevents pattern collapse. In this work we have computed the tensile stresses induced in the top-plate structures due to the capillary forces that arise between the columns due to the surface tension of the drying liquid. We have further studied the dynamic behavior of the structure after an instantaneous force. Based on these results, we have shown that the predicted optimal thickness of the top-plate structure is sufficient to maintain structural integrity.     

UV-LIGA interferometer biosensor based on the SU-8 optical waveguide

SU-8 resist was used as a core/cladding waveguide material to fabricate a Mach–Zehnder interferometer (MZI) for biochemical sensing. The refractive index of the SU-8 resist was fine-tuned with a Δn of 0.004 for single-mode transmission. The UV lithography processes of the SU-8 resist were also optimized to pattern the high resolution (1 μm) and high aspect ratio (A_R = 6) Y-branch structure of the optical interferometer. Optical measurements reveal that the SU-8 MZI chip can efficiently transmit the NIR laser (λ = 1310 nm) with a total loss less than 6 dB. When one branch of the MZI is in contact with the analyte, the interfered intensity stabilizes after the soaking time exceeds 5 min. NaCl solution with a concentration of 10⁻⁹ g/l can be detected using the SU-8 MZI chip. In the future, the polymer MZI chip can be mass-produced by molding process (or the LIGA process). The low-cost, label-free, real-time and high-sensitivity MZI chip will benefit many applications related to biological, environmental and industrial detection.     

A numerical and experimental study on gap compensation and wavelength selection in UV-lithography of ultra-high aspect ratio SU-8 microstructures

This paper presents a study on UV-lithography of thick SU-8 resist using air gap compensation and optimal wavelength selection for ultra-high aspect ratio microstructures. Both numerical simulations and experiments were conducted to study effects of different lithography conditions: broadband light source with and without air gap compensation, filtered light source with glycerol liquid, and filtered light source with Cargille refractive index matching liquid. A thick PMMA sheet was used as an optical filter to eliminate most of the i-line components of a broadband light source. Using the filtered light source and gap compensation with the Cargille refractive index liquid perfectly matching that of SU-8, patterns with feature sizes of 6 μm thick, 1150 μm tall (aspect ratio of more than 190:1) and high quality sidewalls were obtained. Microstructures with height up to 2 mm and good sidewall quality were also obtained and presented. The study also proved that Cargille refractive index matching liquid is compatible with UV-lithography of SU-8 and may be used as an effective air gap compensation solution.     

基于STC8A8K+MS5837的高精度船舶吃水监测系统的设计

为提高船舶吃水检测精度,研制了基于STC8A8K+MS5837的高精度船舶吃水监测系统;该系统利用压力传感器MS5837高精度的特点,并结合液体压强与深度的关系解决船舶吃水测量精度低的问题,同时单片机STC8A8K将吃水数据通过RS485总线发送给上位机;上位机以Cortex-A9处理器为核心,搭载了Linux操作系统,液晶屏上可以显示实时数据,并且可以通过USB接口导出测量数据,保存数据以供后续研究;现场实验表明,该系统具有安装方便、实时性高的优点,其测量精度可达0.1 mm。     

Simulation and experimental validation of a SU-8 based PCR thermocycler chip with integrated heaters and temperature sensor

We present a SU-8 based polymerase chain reaction (PCR) chip with integrated platinum thin film heaters and temperature sensor. The device is fabricated in SU-8 on a glass substrate. The use of SU-8 provides a simple microfabrication process for the PCR chamber, controllable surface properties and can allow on chip integration to other SU-8 based functional elements. Finite element modeling (FEM) and experiments show that the temperature distribution in the PCR chamber is homogeneous and that the chip is capable of fast thermal cycling. With heating and cooling rates of up to 50 and 30 °C/s, respectively, the performance of the chip is comparable with the best silicon micromachined PCR chips presented in the literature. The SU-8 chamber surface was found to be PCR compatible by amplification of yeast gene ribosomal protein S3 and Campylobacter gene cadF. The PCR compatibility of the chamber surfaces was enhanced by silanization.