Low-cost origami fabrication of 3D self-aligned hybrid microfluidic structures

3D microfluidic device fabrication methods are normally quite expensive and tedious. In this paper, we present an easy and cheap alternative wherein thin cyclic olefin polymer (COP) sheets and pressure sensitive adhesive (PSA) were used to fabricate hybrid 3D microfluidic structures, by the Origami technique, which enables the fabrication of microfluidic devices without the need of any alignment tool. The COP and PSA layers were both cut simultaneously using a portable, low-cost plotter allowing for rapid prototyping of a large variety of designs in a single production step. The devices were then manually assembled using the Origami technique by simply combining COP and PSA layers and mild pressure. This fast fabrication method was applied, as proof of concept, to the generation of a micromixer with a 3D-stepped serpentine design made of ten layers in less than 8 min. Moreover, the micromixer was characterized as a function of its pressure failure, achieving pressures of up to 1000 mbar. This fabrication method is readily accessible across a large range of potential end users, such as educational agencies (schools, universities), low-income/developing world research and industry or any laboratory without access to clean room facilities, enabling the fabrication of robust, reproducible microfluidic devices.     

用于微流控制备的3D打印机设计

针对微流控芯片传统加工工艺成本较高,工时较长等问题提出了一种低成本、适用于微流控芯片制备的3D打印机设计方案,该设计方案由3D打印机本体和上位机控制软件组成,其中上位机控制软件负责将事先建好的三维模型进行分析、切片,并生成G-code格式文件;3D打印控制系统负责接收、解析G-code文件及转化为打印机可识别的控制指令以完成物体的快速成型。详细阐述了3D打印机各功能模块的具体实现,给出了测试打印结果,证明该打印机具有成本低、精度高的优点。     

A combination of 3D printing and PCB technologies in microfluidic sensing device fabrication

Microsystem Technologies - Microfluidic devices are increasingly being used as analytical systems, biomedical devices, chemistry and biochemistry instruments, and basic research systems....     

The design and fabrication of polymerase chain reaction platform

Thermalcycler was extensively used machine for amplify DNA sample. One of the major problems in the working time was that it spent most of time for cooling and heating. In order to improve the efficient, the study presented a novel method for amplify DNA sample. For this concept, the DNA sample in the silicon chamber which was pushed by a tappet through the three temperature regions around a center and then the DNA segments could be amplified rapidly after 30 cycles. The polymerase chain reaction (PCR) platform was composed of the thin-film heaters, Cu plates, DC powers, and temperature controllers. The photolithography and bulk etching technologies were utilized to construct the thin-film heater and DNA reaction chambers. Finally, 1 μl 100 bp DNA segment of Escherichia coli K12 was amplified successfully within 36 min on this PCR platform.     

The design and fabrication of autonomous polymer-based surface tension-confined microfluidic platforms

A one-step thick film printing process has been established for patterning hydrophobic polyvinyl chloride (PVC) substrate materials with hydrophilic cellulose acetate. The opposing patterned substrate materials are brought within close proximity utilizing spacer material of defined thickness. The parallel-plate configured devices are capable of supporting autonomous fluid transport through capillarity. Minimum attainable path widths of 313.3 ± 17.9 μm can be achieved utilizing an affordable personal printer for photomask generation. In addition, a theoretical model for this system predicting meniscus position as a function of time and system architecture is posed along with experimental data which is found to be in good agreement with the model. Lastly, the curvature of the surface is approximated and exploited for the determination of the true pressure jump across the curved surface at the gas–liquid interface at all points on a discretized surface. The curvature associated pressure jump results are found to be consistent with the Laplace pressure approximation.

Structure design and system integration of 3D camera platform

This article is focusing on designing a new type of high-strength, high-precision and three-dimensional (3D) parallel film shooting platform, which not only supports the cameras but also adjusts the two cameras’ distance and angle manually or automatically. Firstly, the design of the head structure of the stent comprises three layers, a bottom bracket, an intermediate bracket and a top bracket. Secondly, the main part of system integration includes a communication module and a control module. Actually, in the communication module, a chip NEC infrared remote control is used as a source of remote control signals, including the information about the stepper motor, such as rotation direction, revolution per minute and working condition. In addition, the control module is based on the microcontroller stepper motor of the STC89C51, and the stepper motor is driven by a driver chip L298N, which controls the direction and the rotation angle. Finally, the related software is programmed under C language environment in Keil uVision3. Compared with the traditional platform cameras, the new camera platform has strong stiffness, high precision and a solid structure, and it can be remotely controlled to meet the requirements of various professional shooting environments.     

Design and fabrication of a novel microfluidic nanoprobe

The design and fabrication of a novel microfluidic nanoprobe system are presented. The nanoprobe consists of cantilevered ultrasharp volcano-like tips, with microfluidic capabilities consisting of microchannels connected to an on-chip reservoir. The chip possesses additional connection capabilities to a remote reservoir. The fabrication uses standard surface micromachining techniques and materials. Bulk micromachining is employed for chip release. The microchannels are fabricated in silicon nitride by a new methodology, based on edge underetching of a sacrificial layer, bird's beak oxidation for mechanically closing the edges, and deposition of a sealing layer. The design and integration of various elements of the system and their fabrication are discussed. The system is conceived mainly to work as a "nanofountain pen", i.e., a continuously writing upgrade of the dip-pen nanolithography approach. Moreover, the new chip shows a much larger applicability area in fields such as electrochemical nanoprobes, nanoprobe-based etching, build-up tools for nanofabrication, or a probe for materials interactive analysis. Preliminary tests for writing and imaging with the new device were performed. These tests illustrate the capabilities of the new device and demonstrate possible directions for improvement.     

三维微弹簧型MEMS探卡的设计和制备

随着IC器件上的I/O尺寸减小和密度增加,与之通过接触来进行电性能测试的探卡密度也要相应增加,传统手工制作的环氧树脂针形探卡难以满足使用要求,使用MEMS技术制作探卡成为发展的趋势,但是当前MEMS探卡的主要问题是不能承受和产生破坏焊垫表面氧化层和污染层所需的应力.本文提出了一种简支梁结构、通过多次电镀工艺制作的三维弹性MEMS探卡,这种探卡可以承受更大应力,并且具有较小的自身电阻.针对间距为250 μm阵列排布的器件I/O,使用ANSYS有限元方法对弹簧型探卡进行了结构分析和设计,采用UV-LIGA工艺制备探卡,最后对探卡的力学性能进行了测试.     

Chitosan microfiber fabrication using a microfluidic chip and its application to cell cultures

In this study, a poly-methyl-methacrylate (PMMA) microfluidic chip with a 45° cross-junction microchannel is fabricated using a CO₂ laser machine to generate chitosan microfibers. Chitosan solution and sodium tripolyphosphate (STPP) solution were injected into the cross-junction microchannel of the microfluidic chip. The laminar flow of the chitosan solution was generated by hydrodynamic focusing. The diameter of laminar flow, which ranged from 30 to 50 μm, was controlled by changing the ratio between chitosan solution and STPP solution flow rates in the PMMA microfluidic chip. The laminar flow of the chitosan solution was converted into chitosan microfibers with STPP solution via the cross-linking reaction; the diameter of chitosan microfibers was in the range of 50–200 μm. The chitosan microfibers were then coated with collagen for cell cultivation. The results show that the chitosan microfibers provide good growth conditions for cells. They could be used as a scaffold for cell cultures in tissue engineering applications. This novel method has advantages of ease of fabrication, simple and low-cost process.     

Improvements in operations management applied to a 3D simulation connected to a physical platform

Logistics are a key factor for manufacturing companies in developed countries to better exploit their competitive advantages of proximity to market and flexibility. In order to improve the management of a logistics/distribution center, this paper proposes the use of control methods based on Multi-Agent Systems enhanced with Radio-Frequency Identification. However, the best way to demonstrate the benefits of using these solutions, is to apply them to a real company; but, naturally, this is impractical. In this paper, an experimental platform composed of a 3D simulation combined with a physical miniature model is used to illustrate the proposed control methods. The set-up described here has been assembled in the AUTOLOG laboratory at the University of Castilla-La Mancha in Spain. The design of the platform is somewhat generic, allowing adaptation to different distribution problems, but has been inspired on a real local facility. The objective of this system is to provide a test-bench to experiment with multidisciplinary theories, techniques, and algorithms that can be grouped into four areas: automation and robotics, instrumentation and control, production planning, and logistics and distribution.     

Efficient batch-mode mixing and flow patterns in a microfluidic centrifugal platform: a numerical and experimental study

During recent years centrifugal-based microfluidic devices known as Lab-on-a-CD have attracted a lot of attentions. Applications of these CD-based platforms are ubiquitous in numerous biological analyses and chemical syntheses. Mixing of different species in microscale is one of the essential operations in biochemical applications where this seemingly simple task remains a major obstruction. Application of centrifugal force, however, may significantly improve the flow agitation and mixing, especially when it is combined with the Coriolis force which acts perpendicular to centrifugal force. In this study, mixing process in minichambers located on a rotating platform under a periodic acceleration and deceleration angular velocity profile is investigated both numerically and experimentally. We have incorporated various arrangements of obstacles and baffles, which are usually used in stationary mixers, within a batch-mode rotating mixing chamber. Subsequently, the effect of these obstacles on flow field and mixing process has been studied, and among these arrangements four cases have been selected for further experimental analysis. Experimental studies have been performed on a multi-layer CD platform fabricated in polycarbonate plates, and subsequently mixing has been investigated in these minichambers. The quantitative mixing data were obtained after a set of image analyses on the captured images of mixing chamber during the process and the results were compared with the simulation. The results indicate a good resemblance between the two studies both qualitatively and quantitatively. Furthermore, it has been shown that the application of obstacles and baffles together in chamber results in reducing the mixing time more than 50 % as compared to a chamber without any obstacle and/or baffle configuration. Obtaining mixing times less than 10 s in both studies, makes these CD-based platforms an appropriate device for many applications in which a cost-effective device as well as low mixing time is required.

     

基于三维头型及穴位分布的辅助设计平台的研究

为设计适合中国人头型的头戴产品,提高产品佩戴时的适配性和舒适性,开展了 辅助头戴产品设计的图形化平台的研究。首先基于国家标准重构了5 种标准头型的三维头部数 字化模型,并根据不同头型的第5,50 和95 百分位的头型缩放因子,构造了共15 个三维数字 化头型;然后根据中医理论中的穴位分布及定位方法,在所构造的头型上建立了7 条经络和78 个穴位的三维分布模型。采用三维网络图形开发包Three.js 开发了头戴产品辅助设计平台,实 现了多百分位头型的连续变形、头部穴位动态定位及基准平面剖切功能,可对头戴产品的穴位 点匹配、贴合区域间隙和干涉等进行适配性分析。以某头戴按摩仪为例开展试戴及适配性分析, 可有效发现该产品结构上存在的问题。该研究可为相关头戴产品的适配性分析提供参考。     

Integration of impedance spectroscopy sensors in a digital microfluidic platform

Digital microfluidics combines the advantages of a low consumption of reagents with a high flexibility of processing fluid samples. For applications in life sciences not only the processing but also the characterization of fluids is crucial. In this contribution, a microfluidic platform, combining the actuation principle of electrowetting on dielectrics for droplet manipulations and the sensor principle of impedance spectroscopy for the characterization of the fluid composition and condition, is presented. The fabrication process of the microfluidic platform comprises physical vapor deposition and structuring of the metal electrodes onto a substrate, the deposition of a dielectric isolator and a hydrophobic top coating. The key advantage of this microfluidic chip is the common electric nature of the sensor and the actuation principle. This allows for fabricating digital microfluidic devices with a minimal number of process steps. Multiple measurements on fluids of different composition (including rigid particles) and of different conditions (temperature, sedimentation) were performed and process parameters were monitored online. These sample applications demonstrate the versatile applications of this combined technology.     

AVS 3D实时解码器在FPGA/SoC平台上的设计与实现

AVS(audio video coding standard)工作组针对3D视频提出了双目立体视频编解码方案。以AVS双目拼接算法为核心,通过FPGA硬件加速模块完成双目立体ES流的语法元素解析,与So C开发板Xilinx ZYNQ 7020协同工作,创新性地在FPGA/So C协同平台上实现了AVS 3D实时解码器。通过HDMI接口将解码数据输出到三维显示设备,得到了具有深度信息的3D视频,验证了AVS 3D实时解码器的有效性。     

Simulation, fabrication and characterization of a 3D piezoresistive force sensor

In this contribution we report on a miniaturized bulk micro-machined three-axes piezoresistive force sensor. The force sensor consists of a full membrane with 16 conventional two terminal p-type diffused piezoresistors on the surface of the membrane. The die size of the chip is 6.5 mm × 6.5 mm. Piezoresistors with four different designs were placed on the membrane. Sensitivities were found to be in the range of 0.37–0.79 mV/(V mN) and 1.68–2.92 mV/(V mN) in Z-direction and X- or Y-direction, respectively. The stiffness of the measured microprobes in the range of 5–8 mN/μm and 0.27–0.48 mN/μm were obtained in vertical and lateral direction, respectively. Various single and twin membranes designs were simulated to calculate stiffness of the microprobe. The measurement results show a cross-axis sensitivity of <2.5% at full scale of 25 mN.     

Additive fabrication of a 3D electrostatic energy harvesting microdevice designed to power a leadless pacemaker

Microsystem Technologies - This paper presents the development of a process enabling to fabricate complex three-dimensional nickel microdevices. The possibilities offered by this new process are...     

A numerical design study of chaotic mixing of magnetic particles in a microfluidic bio-separator

A two-dimensional numerical investigation into the mixing of magnetic microparticles with bio-cells in a chaotic micromixer is carried out by using a multiphysics finite element analysis package. Fluid and magnetic problems are simulated in steady-state and time-dependent modes, respectively. Intensity of segregation is utilized as the main index to examine the efficiency of the mixer. Trajectories of the particles are used in order to detect chaos in their motion and quantify its extent. Moreover, probability of the collision between particles and target bio-cells is examined as a supplemental index to study the effects of driving parameters on the mixing process. Simulation results reveal that while in some ranges of operating conditions all indices are in good agreement, there are some ranges where they appear to predict contradicting results which is discussed in details. It is found that optimum operating conditions for the system is obtained when the Strouhal number is less than 0.6, which corresponds to the efficiency of about 85% in a mixing length of 500 μm (The mixer design described here is patent pending).