一种自封装技术制备PMMA微流控通道方法研究

本文结合湿法腐蚀技术、紫外固化纳米压印技术、热压纳米压印技术制备出聚甲基丙烯酸甲酯(PMMA)沟槽微结构,基于局部加热的自封装技术成功制备出了PMMA微流控通道。研究了硅模板结构参数的选择要求以及工艺过程中实验参数对实验的影响。实验结果表明,热硅片与基片相对运动方向应与PMMA沟槽微结构方向平行,有利于制备出变形量小、尺寸均匀的微流控通道。     

聚合物微流控芯片的注射成型

针对注塑成型微流控芯片过程中出现翘曲变形和微通道复制精度不高等缺陷,采用正交分析法,仿真优化了芯片厚度方向上的翘曲变形;基于翘曲优化结果,实验研究了微注射成型微流控芯片过程中模具温度、熔体温度和注射速度对微通道变形的影响。结果表明,保压时间和保压压力对微流控芯片的翘曲变形影响最大,而模具温度对微通道变形影响最为显著。采用优化的工艺参数,所成型的芯片微通道具有较高的复制度,无明显翘曲变形,可满足使用要求。     

微流控芯片基片与盖片一体化注塑成型研究

针对微流控芯片基片与盖片的结构特点,提出了定模先行抽芯机构,设计制造了微流控芯片基片与盖片一体化注塑成型模具,并进行注塑成型试验研究.结果表明:定模先行抽芯机构可以有效解决盖片上圆孔状储液池成型与脱模的技术难题,如何使微通道复制完全是微流控芯片基片注塑成型的主要技术难点;模具温度对提高微通道复制度起决定性作用,注射速度和熔体温度是次要因素,而注射压力相对其他因素影响力较差,但必须保持在一个较高的水平,依此形成塑料微流控芯片的注塑成型工艺规范.     

环烯烃聚合物(COP)微流控芯片的制备及其与聚甲基丙烯酸甲酯(PMMA)微流控芯片的性能对比

采用热压方法制备了环烯烃聚合物(COP)微流控芯片.考虑到温度对微结构热压成形的质量影响最大,基于材料的粘弹性特性,通过变温准蠕变实验获得了热压参考温度Tr.实验证明,在该温度下热压成形,宽度和深度方向的复制精度分别达到了97.6%和94.3%.为了研究制备的COP微流控芯片的性能,将其和同一模具制备的PMMA微流控芯片进行了性能对比实验.通过背景荧光实验、电泳实验和DNA分析实验三方面的研究表明,与PMMA芯片相比,COP芯片背景荧光低,电泳效率高,检测重现性相对标准偏差小于2.5%,适用于生化分析.     

注射成型工艺对微流控芯片微通道尺寸均匀性的影响

为了制造微通道尺寸均匀的微流控芯片,提出以梯形微通道上宽和深度的标准差来表征尺寸均匀性,研究了注射成型工艺参数对环烯烃类共聚物(COC)微流控芯片微通道尺寸均匀性的影响规律,为工艺参数的设置提供指导。结果表明,工艺参数对微通道上宽的影响较大,上宽标准差的最大极差为3.82μm;对微通道深度影响较小,深度标准差的最大极差为0.61μm。此外,模具温度对微通道尺寸均匀性的影响最显著,模具温度从80℃上升至120℃,微通道尺寸均匀性先略微下降,后逐渐提高,最低上宽标准差为3.24μm,下降幅度为54%。保压压力对微通道尺寸均匀性的影响最小,保压压力从80 MPa增加至120 MPa,微通道的尺寸均匀性逐渐提高,但最大标准差极差仅为1.29μm。     

聚合物微流控芯片超声波微熔融键合方法

为了将超声波聚合物焊接技术更好地应用于聚合物微流控芯片的键合,提出基于界面微熔融的聚合物微流控芯片超声波键合方法.设计了适用于该方法的导能筋结构,在合理的键合工艺参数控制下使导能筋结构材料不发生熔融流延,通过键合界面软化润湿来实现对微流控芯片微通道的密封连接.实验结果表明,键合时间仅为0.09 s,键合后微通道的承压能力可达6个大气压,满足微流控芯片的使用要求.面接触导能筋可采用机械加工或注塑方法获得,具有良好的产业化应用前景.     

压印成型条件对微透镜结构影响的模拟

利用Polyflow模拟热压印中微结构的充模过程,并以微透镜为例研究了在热压印中高分子材料在微结构充模时,压印温度、压力、速度、孔的大小、基片厚度等物理量变化对微透镜成型结构的影响规律。模拟结果表明,微透镜在成型初期,不同位置的曲率半径不同;随着压印过程的进行,各个位置的曲率半径逐渐减小最终趋于一致;压印速度越快,压印成型时间越短;多孔压印比单孔压印所需的时间要长;同时减小孔间距,孔周围流体速度增加,将影响微透镜成型的均匀性;增加基片厚度对曲率的减小影响甚微,靠增加基片厚度缩短成型时间的效果不太明显。     

PDMS微流控电泳芯片的快速制备

采用Protel软件绘制微流控沟道的形状,利用电路板制作技术加工出模具.该芯片由PDMS基片和PDMS盖片组成,微流控沟道位于基片上,深度和宽度分别为75μm和100μm,由盖片对其进行密封.考察了有绝缘漆模具和无绝缘漆模具制作的芯片的电泳分离情况.在所制作的PDMS微流控电泳芯片上对用异硫氰酸酯荧光素标记的氨基酸进行了电泳分离,当信噪比S/N=3时,最小检测浓度达到0.8×10-11mol/L.     

新型纳米磁色谱微流体芯片

通过标准光刻电铸工艺,在玻璃基片上制备了不同形状的顺磁性镍铁微柱阵列作为微流控通道内的磁力元件;通过SU-8胶光刻模板PDMS快速成型制备了微流控通道结构,通过O2 Plasma 处理和显微镜下对准,实现在玻璃基片上的永久封装,制备了磁分离微流控芯片;在微流控通道中引入含有微磁珠的溶液,通过外加磁场和流动式进样,观察微磁珠的对磁场的响应情况以及层流中的磁珠分离情况及捕获,并进行了DNA提取实验.     

等温准热压印中聚合物微结构成型的分析

在传统平板微热压印中,模具需要反复的加热和冷却,工艺循环时间长,存在微结构成型效率低的缺点。文中创新性地提出一种等温准热压印工艺,可有效解决这一问题。首先在研究此工艺原理的基础上,采用有限元模拟的手段探究聚合物微结构的成型过程。模拟分析可知,聚合物微结构的成型是边冷却边压印的过程,模具温度显著影响微结构的复制精度;而聚合物基片预热温度过高不会提高微结构的复制精度,却增加了脱模缺陷的可能性。模拟得到的规律可为等温准热压印实验工艺参数的选取提供依据。最后通过实验验证了模拟规律的正确性及工艺的可行性。     

Air cushion press for excellent uniformity, high yield, and fast nanoimprint across a 100 mm field

Imprint pressure uniformity is crucial to the pattern uniformity and yield of nanoimprint lithography (NIL) and, hence, its applications. We studied a novel imprint method, air cushion press (ACP), in which the mold and substrate are pressed against each other by gas pressure rather than solid plates, and compared it with a common method, solid parallel-plate press (SPP). We found that (a) under normal imprinting conditions the measured pressure distribution across a 100-mm-diameter single imprint field in ACP is nearly an order of magnitude more uniform; (b) ACP is immune to any dust and topology variations on the backside of the mold or substrate; (c) when a dust particle is between the mold and substrate, ACP reduces the damage area by orders of magnitude; (d) ACP causes much less mold damage because of significantly less lateral shift between the mold and substrate; and (e) ACP has much smaller thermal mass and therefore significantly faster speed for thermal imprinting.     

微细超声工作台的设计与微振幅测量

微细超声工作台是微细超声加工机床与微细超声振动辅助加工机床的关键零部件,其振幅值直接影响加工精度与加工效率。传统的振幅测量方法很难准确的测出微细超声工作台的微振幅。基于精密微三维运动平台的高分辨率,提出了一种恒力控制的微振幅测量方法,成功的测量出能精确到0.1微米的微振幅。本文首先对微细超声工作台中的微细超声振动系统进行了理论设计,然后采用基于恒力控制的超声振幅测量方法,对不同功率作用下的微细超声振动系统的振幅值进行了测量。     

基于收缩流动的气体超声流量计声道稀疏化及测量方法

为了提高低声道数超声流量计的准确度水平,在传统超声流量计的基础上设计了一种具有收缩流动结构的低声道数超声流量计。采用数值模拟研究了渐缩管中收缩流动的流场特征,确定了渐缩管的几何参数及超声探头的安装方式。通过空气实流实验,研究了单声道及双声道在收缩流动条件下流量计量的基本特性。在流量范围27~432m3/h,管径范围100~150mm进行了实验验证。结果表明:收缩流动的数值模拟结果与理论模型相吻合,当渐缩管的收缩比由2增大为6,被测流场均匀区占比显著增大;当收缩比固定不变时,随着流量的增大,边界层厚度显著降低。通过实流实验比较不同结构和配置超声流量计的测量结果,发现单声道收缩管超声流量计的准确度水平显著优于传统单声道气体超声流量计,与传统双声道气体超声流量计的准确度水平相当。     

G2.5超声波燃气表的仿真与实验研究

超声波流量计在中低压燃气测量领域中,由于燃气压力小、流量变化大、流速低等因素会导致其测量精度低.针对以上问题,设计两种不同的基表结构,通过流体动力学仿真计算,获得了两种基表结构在不同流量点的流场分布,通过对超声波传播路径区域的流场速度的大小和分布均匀性分析,确定更为合理的测量管路结构.最后通过设计相关实验,验证了流场仿...     

纵向超声波辅助微注塑方法

微注塑过程中,聚合物熔体在微小腔体中流动时充模阻力比常规注塑大,这影响了熔体填充效果,同时热量损失的不均衡性和不确定性容易导致注塑精度不高．提出了纵向超声波辅助微注塑方法,并对超声波振动对聚合物熔体的作用机理进行了探讨,分析了超声换能器结构对应力、振幅和响应频率的影响．基于对微注塑过程的模拟结果,开发了纵向超声波辅助微注塑装置．通过在微注塑过程中纵向超声波对熔体的能量作用降低熔体黏度,改善了熔体流动和充填性能．为了验证超声波辅助微注塑的效果,进行了菲涅尔透镜实际注塑实验．实验结果表明,相同的注塑工艺条件下,超声辅助微注塑过程中聚合物熔体的充填性能提高了6．91％．     

Multicriteria evaluation and optimization of the ultrasonic sealing performance based on design of experiments and response surface methodology

Proper closure is an essential packaging quality aspect and can, amongst others, be achieved with ultrasonic sealing. The ultrasonic sealing performance depends on the film type, and the seal settings, such as seal time, applied force and ultrasonic amplitude. Because these parameters are less intuitive than heat seal parameters and optimal settings are undefined for many films, this work presents an efficient approach to evaluate the effect of these settings on the ultrasonic sealing performance. An experimental design defines the experiments to perform. A response surface methodology is then used to model the relation between seal settings and sealing performance. Based on these models, the seal settings are optimized. As there are several criteria to express sealing performance, single‐criteria and multicriteria optimizations are described. The approach was illustrated for a polyethylene terephthalate/linear low‐density polyethylene‐C4 film. The seal settings were optimized to obtain high seal strength, limited ultrasonic horn displacement, and low seal energy. The optimum settings were 0.1 seconds (seal time), 4.32 N/mm (force), and 28.75 μm (amplitude). The predicted optimum strength, horn displacement, and energy were 2.32 N/mm, 40 μm, and 11.66 J, respectively. Besides the optimum, the seal window is also of interest. A broad seal window ensures sufficient seal strength for a wide range of settings. For the polyethylene terephthalate/linear low‐density polyethylene‐C4 film, a strength of ≥90% of the optimum was obtained for 39% of the input combinations within the design space. The presented approach is widely applicable (other films and sealing processes) since it is flexible in the input parameters, design, and responses.     

Optical characterization of an unknown single layer: Institut Fresnel contribution to the Optical Interference Coatings 2004 Topical Meeting Measurement Problem

We present the characterizations performed at the Institut Fresnel for the Measurement Problem of the Optical Interference Coatings 2004 Topical Meeting. A single layer coated on a fused-silica substrate of unknown composition and parameters is analyzed in terms of optogeometrical parameters, uniformity, and scattering. We determine the refractive index and the average thickness of the coating, then provide the localized determination of the thickness with a 2 mm spatial resolution. Topography measurements include atomic force microscopy and angle-resolved scattering measurements. These results are completed thanks to a Taylor Hobson noncontact 3D surface profiler.     

基于JJG(闽)1086-2018放射治疗CT模拟定位机X射线辐射源的质控分析

整个精确放疗流程最关键、最基础的一个环节就是定位CT扫描精确程度,做好定位CT的质控关乎整个放疗流程的成败。介绍了JJG(闽)1086-2018放射治疗CT模拟定位机X射线辐射源在检定和质控中的流程和方法,从剂量性能要求、图像成像质量和机器机械精度方面对CT模拟定位机的质量控制做了定量的要求。连续8个月的测试结果表明:CT测量值误差在30HU以内,图像均匀性≤5.0HU,空间分辨力7Lp/cm,低对比度分辨力在对比度为1.0%,0.5%,0.3%时分别≤3.0mm,≤5.0mm,≤6.0mm,达到了规程的要求。CT模拟定位机的图像质量和机械精确程度得到了很好的保障,定位CT的剂量准确,影像参数和位置精确度有规可循。     

Construction of 3D Polymer Brushes by Dip‐Pen Nanodisplacement Lithography: Understanding the Molecular Displacement for Ultrafine and High‐Speed Patterning

Dip‐pen nanodisplacement lithography (DNL) is a versatile scanning probe‐based technique that can be employed for fabricating ultrafine 3D polymer brushes under ambient conditions. Many fundamental studies and applications require the large‐area fabrication of 3D structures. However, the fabrication throughput and uniformity are still far from satisfactory. In this work, the molecular displacement mechanism of DNL is elucidated by systematically investigating the synergistic effect of z extension and contact time. The in‐depth understanding of molecular displacement results in the successful achievement of ultrafine control of 3D structures and high‐speed patterning at the same time. Remarkably, one can prepare arbitrary 3D polymer brushes on a large area (1.3 mm × 1.3 mm), with <5% vertical and lateral size variations, and a patterning speed as much as 200‐fold faster than the current state‐of‐the‐art.     

Improvement of thickness uniformity and crystallinity of AlN films prepared by off-axis sputtering

We improved both the thickness uniformity and crystallinity of Aluminum nitride (AlN) films deposited by off-axis sputtering. The results in thickness uniformity and X-ray rocking curve full-width at half-maximum (FWHM) of AlN (0 0 0 2) are achieved to be ±0.2% and 1.4°, respectively on a 100 mm Si (1 0 0) substrate. The residual stress can be controlled from tensile to compressive by varying sputtering parameters such as gas pressure, RF power and DC bias voltage applied to a substrate without degradation in the crystallinity and thickness uniformity.