柔性膜式微型电磁驱动器的设计与仿真分析

硅橡胶具有生物兼容性好且制作技术与微细加工工艺兼容的优点,采用硅橡胶作为MEMS驱动器中的振动膜具有较好的应用前景。研究了一种微型电磁驱动器,由内嵌永磁体阵列的柔性硅橡胶(PDMS)振动膜和线圈两层构成,采用电镀工艺制作线圈层;采用电镀方法制作磁体阵列,由甩胶机旋涂硅橡胶并进行固化,制作内嵌磁体阵列的硅橡胶膜,对磁体磁化后可作为双向驱动器。对该驱动器进行了理论分析与数值模拟,采用有限元分析工具ANSYS对微驱动器的电磁驱动力及其挠度进行分析,二者结果基本一致,振动膜中心最大挠度的分析误差为7.96%,其一阶固有频率的分析误差为16.1%。     

双腔并联式无阀压电微泵的设计及制作

为了实现微流控芯片的小型化、集成化,设计并制作了一种可定量连续输送微量液体的无阀压电微泵.该微泵采用双腔并联式结构,利用微机电系统(MEMS)技术在硅基片上制作了具有扩散口/喷口无阀结构的出入水口,采用压电双晶片作为驱动部件,以聚二甲基硅氧烷(PDMS)作为泵膜.测试结果表明,泵膜的厚度、工作频率和电压对微泵的输出流速均有明显的影响,在频率1100 Hz及电压80 V时,双腔体并联式无阀压电微泵的最大流速为210μL/min,约为相同结构单腔体微泵流速的1.5倍.     

一种无阀压电微泵的研究

介绍了一种适用于微流体系统的无阀微泵。该微泵利用聚二甲基硅氧烷(PDMS)作为泵膜,利用硅各向异性腐蚀形成扩散口/喷口结构,并利用压电双晶片作为驱动部件。该微泵的制作工艺简单,使用寿命长,具有良好的液体驱动性能。对于使用15 mm长的压电双晶片作为驱动器的压电无阀微泵,在100 V6、0 Hz、占空比为1的方波驱动下,最大流速可达151μL/min。     

基于MEMS的无阀泵研究进展

微流体控制系统是微机电集成系统(MEMS)一个主要分支,微泵作为微流体控制系统的重要组成部分,根据其有无阀片可分为有阀型微泵和无阀型微泵.无阀型微泵由于其结构相对简单、制造工艺要求不高,因而有着独特的发展优势.主要介绍了基于MEMS的扩张管/收缩管型无阀泵几年来在结构设计、制作工艺等方面的研究成果、现状和发展前景.     

微机电系统技术：—硅基微加工

当前流行的硅基做加工技术主要有体微加工（bulkmieromachining）和表面做加工（sutheemic。achini。）两种。它们之间的主要区别为：前者将微机械的运动部件制作在硅衬底里,后者则将微机械运动部件制作在硅衬底表面上的薄膜里”健体微加工技术目前用体微加工技术制作的主要产品有：某些压力传感器、加速度传感器。微泵、微阀、微沟槽等微传感器、微机械和微机械零件等,这些产品的微结构的显著特点是它们都有可运动的悬臂梁或桥、可振动的膜或硅衬底里的沟槽。这些微结构的形成主要利用腐蚀技术和光刻技术相结合,有选择地从硅衬底上挖去…     

多孔硅技术在硅基微型燃料电池中的应用

多孔硅作为一种新型材料，利用其疏松多孔的特性及与IC加工的兼容性，将其用于硅微质子交换膜燃料电池的研究中，作为其电极扩散层，对多孔硅膜的性能、制备工艺及多孔硅膜表面金属淀积工艺进行了研究，提出一套基于MEMS加工技术和薄膜淀积技术的制作硅微质子交换膜燃料电池的工艺。     

基于(111)硅单片集成三轴加速度计的工艺研究北大核心

介绍了一种新型单片集成电容式三轴微加速度计的加工方法,该方法采用非绝缘体上硅(SOI)的单硅片单面加工技术,易于与IC工艺兼容,而且成本低廉,成品率高,适用于批量生产,可替代传统的SOI工艺。该方法主要利用硅深度反应离子刻蚀(DRIE)技术结合普通(111)单晶硅片内部可选择性横向自停止腐蚀技术制作并释放得到悬浮可动的敏感结构。此外,创新的锚点设计不仅使检测电极之间相互电学隔离,而且便于引线键合与封装。最后基于开环接口电路对加工制造的三轴加速度计进行了测试,验证了该工艺的可行性。     

基于PMMA的微泵研制

无阀微泵经常被使用是为了直接控制微泵的流量,它避免了阀片的不稳定性引起的微泵失效。本文叙述了以聚合物PMMA为材料来制作微流体器件微泵,给出微流体制作工艺的几种方法并从中选出适合于PMMA微泵制作方法,进行无阀微泵制作与测试,最后对用PMMA材料制作的微泵进行了流量和背压的测试。     

一种具有"8悬臂梁-质量块"结构的新型硅微加速度计

提出了一种具有"8悬臂梁-质量块"结构的新型三明治式硅微机械电容式加速度计,用微机械加工工艺在(111)硅片上制作出了具有信号输出的器件.该加速度计的惯性质量块由同一(111)硅片上下表面对称分布的8根悬臂梁支撑.这些悬臂梁是利用(111)硅在KOH溶液中的各向异性腐蚀特性结合深反应离子刻蚀(DRIE)实现的,其尺度精确可控,保证了结构的对称性.该加速度计的谐振频率为2.08kHz,品质因子Q为21.4,灵敏度为93.7mV/g.     

一种具有“8悬臂梁-质量块”结构的新型硅微加速度计

提出了一种具有"8悬臂梁-质量块"结构的新型三明治式硅微机械电容式加速度计,用微机械加工工艺在(111)硅片上制作出了具有信号输出的器件.该加速度计的惯性质量块由同一(111)硅片上下表面对称分布的8根悬臂梁支撑.这些悬臂梁是利用(111)硅在KOH溶液中的各向异性腐蚀特性结合深反应离子刻蚀(DRIE)实现的,其尺度精确可控,保证了结构的对称性.该加速度计的谐振频率为2.08kHz,品质因子Q为21.4,灵敏度为93.7mV/g.     

Performance analysis of valveless micropump with disposable chamber actuated through Amplified Piezo Actuator (APA) for biomedical application

The precise manipulation of fluid through pumping systems has been the technological challenge in microfluidic applications. The biomedical applications call for precise and accurate delivery of fluid through miniaturized pumping systems. This paper presents a novel valveless micropump for biomedical applications operated by the Amplified Piezo Actuator. Integrating the disposable chamber and reusable actuator with the proposed micropump allows the actuator to be reused and eliminates the possibility of infection or contagion. The micropump was fabricated using low-cost polymeric materials like Polymethylmethacrylate (PMMA), Silicone rubber through CNC milling, Laser Cutting, conventional moulding operation. The micropump chamber, nozzle/diffusers, and a bossed diaphragm constituted disposable part and Amplified Piezo Actuator with structural support formed the reusable part of the micropump. The bossed diaphragm of the pump chamber consists of a central cylindrical protrusion to reduce the force of adhesion on the diaphragm and transmit force required for micropump actuation. A theoretical analysis was performed to assess the effect of diaphragm thickness and the bossed region on the effective stiffness of the diaphragm, which in turn influences the deflection achieved. Besides, an analytical approach has been presented to address the effect of adhesive force on the diaphragm surface due to the residual fluid and chamber depth. The experimental characterization of the micropump was carried out to determine the optimal performance parameters with water, fluids mimicking blood plasma, and whole blood. Based on the experimental results, the pumping rate and head developed by the micropump have been significantly affected by factors such as bossed ratio, diaphragm thickness, depth of the micropump chamber, and viscosity of the fluid. The optimum configuration of the micropump cosidered silicone rubber diaphragm with thickness of 0.20 mm having a bossed ratio of 0.33 and a chamber depth of 1.25 mm. With the optimal operating parameters of 150 V sinusoidal input of frequency 5 Hz, the proposed micropump was capable of delivering 7.192 ml/min, 6.108 ml/min, and 5.013 ml/min of water and blood plasma, whole blood mimicking fluid with the maximum backpressure of 294.00 Pa, 226.243 Pa, and 204.048 Pa respectively. The corresponding resolution, i.e., pumping volume/stroke of the micropump was about 23.972 µl, 20.358 µl, and 16.708 µl, respectively.     

Theoretical analysis and optimization of electromagnetic actuation in a valveless microimpedance pump

The construction of a novel valveless microimpedance pump is proposed and the utilized electromagnetic actuator is designed and optimized in this study. The actuating mechanism comprises an electroplated permanent magnet mounted on a flexible PDMS diaphragm and electroplated Cu coils located on a glass substrate. The electromagnetic force between the magnet and the Cu coils causes the diaphragm to deflect and then creates the accumulative effects of wave propagation and reflection at the junction of the compressible and rigid sections. The resulting pressure gradient in the fluid drives the flow from the inlet to the outlet of the micropump. The constituent parts of the electromagnetic actuator, namely the diaphragm, the microcoils, and the magnet are modeled and analyzed in order to optimize the actuator design. The design models are verified both theoretically and numerically and the relationships between the magnetic force, diaphragm displacement, and diaphragm strength are established. The magnitude of the magnetic force acting on the flexible diaphragm are calculated using Ansoft/Maxwell3D FEA software and the resulting diaphragm deflection simulated by ANSYS FEA software are found to agree with the theoretical predictions. Different diaphragm shapes are investigated and their relative strength and flexibility are compared. It is found that a circular PDMS diaphragm represents the most appropriate choice for the actuating mechanism in the micropump. The desired diaphragm deflection of 15 μm is obtained using a compression force of 16 μN, generated by a coil input current of 0.9 A. The diaphragm deflection can be regulated by varying the current passed through the microcoil and hence the flow rate can be controlled. The valveless microimpedance pump proposed in this study is easily fabricated and can be readily integrated with existing biomedical chips due to its plane structure. The results of the present study provide a valuable contribution to the ongoing development of Lab-on-a Chip systems.     

A novel valveless micropump with electrohydrodynamic enhancement for high heat flux cooling

Integrated microchannel cooling systems, with micropumps integrated into microchannels, are an attractive alternative to stand-alone micropumps for liquid-cooled microchannel heat sinks. A new micropump design capable of integration into microchannels and especially suited for electronics cooling is presented. It combines induction electrohydrodynamics (EHD) with a valveless nozzle-diffuser micropump actuated using a vibrating diaphragm. A comprehensive numerical model of the micropump has been developed to study the combined effect of EHD and valveless micropumping. The numerical model has been validated using theoretical and experimental results from the literature. The flow rate achievable from the new micropump is presented and the effect of several key parameters on the micropump performance investigated.     

微型热致动泵

利用硅微细加工工艺制作出热致动微型泵,该泵采用薄膜型准对称结构设计及双面双金属驱动方式,它具有体积较小、工艺简单、易于集成,效率高和流量较大生平特点。     

无阀微泵泵腔中流体流动的有限元模拟与分析

采用有限元仿真软件ANSYS/FLOTRAN对收缩/扩张型无阀微泵泵腔中流体流动的全过程进行了数值模拟和仿真分析,得到了流体在整个泵腔中的流场构形和流动特性。结果表明,泵腔结构单元的弯道效应与出/入口处流体速度分布的非线性混合将导致腔中的局域涡流现象。通过对3个简单模型的模拟计算,证明了缓冲腔的不同结构对无阀微泵的整流效率有较大影响,是泵腔结构参数优化设计不可忽视的重要环节。     

Electrochemical aspects of new materials and technologies in microelectronics

Major scaling issues, which need to be addressed to continue scaling according to Moore’s law, include increase of transistor leakage due to use of thin gate oxide (about 1 nm limit for SiO₂), power (reaching 100 W/cm²) and RC delay (dielectric constant limit is 1 for air and Cu resistivity increases with scaling down the feature sizes). Integration of new materials and technologies will allow us to continue scaling and improve device performance. Examples of new materials include high-k dielectrics and strained silicon in the frond end of wafer processing, low-k carbon-doped oxide and electroplated copper in the back end of wafer processing as well as electroplated bumps, high thermal conductivity interface, heat sink and heat spreader materials in packaging. Electrochemical technologies will play an increasingly important role in silicon technology due to low cost, use of self-assembly processing and self-aligned growth ability. New electrochemical technologies in silicon processing include copper electroplating (replaced Al interconnect to reduce RC delay and increase reliability), bump electroplating (replaced wire bonding to allow increased I/O and improve reliability), and porous silicon for silicon on isolator fabrication (to reduce transistor leakage). Copper electroplating allows a low R, an excellent gap fill capability and superior materials properties with (111) textured Cu films and large grain size, and a stable and controlled process.     

Fabrication of a two-step Ni stamp for blind via hole application on PWB

This study examined imprint lithography with a two-step Ni stamp to solve the laser process problems and simultaneously form a blind via and layer pattern. The Ni stamp was fabricated by electroplating on a dry-etched Si mold, made from a SOI (silicon on insulator) wafer, and pattern replication. For the pattern transfer of the Ni stamp, hot embossing was performed on SU8-coated BT and Si wafer substrates. The residual layer was of a uniform thickness with an embossed shape of acceptable squareness.     

泵腔结构参数对压电气泵性能影响

为了探究泵腔结构参数对压电气体隔膜泵性能的影响,该文设计了一种压电气体隔膜泵的泵腔结构。首先简述了泵腔的结构设计与工作原理,推导出泵腔出口气流速度的表达式,通过仿真得出泵腔高度、气孔直径对腔体内的瞬时气压、气流速度及气体流量的影响。最后制作了泵腔样机并应用在压电气体隔膜泵中,进行了实验测试及理论分析对比。结果表明,实验结果与理论分析相吻合,输出流量随着腔高的增大而减小,随着气孔直径的增大而增大,这为压电气体微泵的腔体设计提供了理论参考。     

A Two-Wafer Approach for Integration of Optical MEMS and Photonics on Silicon Substrate

This letter reports a novel two-wafer approach which demonstrates an integration of optical microelectromechanical system (MEMS) devices and photonics on a silicon substrate. The great advantage of this novel wafer bonding scheme is the ability to maintain the optical axis of the optical MEMS device at the same axis as the optical components. The bonded two wafers which are partially processed, which allows for further processing on the wafer after bonding. Thus, the critical alignment issue is resolved for devices requiring precise alignment in x-/y-/z-axis. Individual functionalities of optical MEMS device and optical coupling between silicon waveguide, fibers and ball lens are demonstrated. This technology shows the potential for integrating silicon photonics integrated circuit and MEMS components with reconfiguration functions on a single silicon substrate.      

Electrical failure analysis of peristaltic micropumps fabricated with PZT actuators

A detection method based on electrical analysis for valveless peristaltic lead zirconate titanate (PZT) micropump fabrication is proposed. The modified Butterworth-Van Dyke (BVD) model is used to analyze the properties of resistant or capacitive elements related to various failures. The series resistance and parallel capacitance in the BVD model are used to detect faults and classify the failure type. The failure analysis of the micropump assembly process focuses on the three common failures: (a) PZT cracking, (b) uneven silver epoxy distribution, and (c) PZT inversion. The analysis approach combines experimental results with a circuit model to determine PZT micropump fabrication reliability. It can be used to detect defects in peristaltic PZT micropumps and classify failure type.