Microfluidic chips for capillary electrophoresis with integrated electrodes for capacitively coupled conductivity detection based on printed circuit board technology

A simple and low budget microfabrication method compatible with mass production was developed for the integration of electrodes for capacitively coupled contactless conductivity detection (C4D) in Lab on a Chip devices. Electrodes were patterned on a printed circuit board using standard processing. This was followed by lamination-photolithography-lamination to cover the electrodes in dry film photoresist (DFR) using an office laminator. This resulted in a flush, smooth surface on top of the detection electrodes, enabling subsequent integration of a microfluidic network at a distance dictated by the thickness of the DFR (17 μm, 30 μm and 60 μm were used in this work). This process was applied to create two types of detectors, re-usable detectors to be used in combination with a separate microfluidic network and integrated detectors where the microfluidic network is irreversibly sealed to the detector. A poly(dimethylsiloxane) (PDMS) slab containing the microfluidic network was positioned on top of the re-usable detectors to create the PDMS hybrid devices. The integrated DFR devices were created by patterning and sealing the microchannel in DFR using subsequent lamination and lithographic steps. The sensitivity of the C4D made using this new technology for small inorganic cations was between 6 and 20 μM, which is comparable with devices made using significantly more advanced technologies. Where the 17 μm film slightly improved the sensitivity, the use of 30 μm thick insulating films was preferred as these did not impose significant restrictions on the applicable field strengths.     

一种新型柔性触觉阵列传感器信号处理电路设计

依据一种利用压阻特性的3×3点阵的柔性触觉传感器,设计了针对这种新型柔性触觉传感器的信号处理电路。该电路能完成信号放大、阵列信号的选通、A／D转换以及通过LED电路对其信号的采集。并详细地阐述了电路的原理和所用芯片的功能。所设计的信号处理电路能够判断出这种触觉传感器单元所受三维加载力的大小和位置。通过在正向压力的加载试验,验证了电路的可行性。     

Image registration for automated inspection of printed circuit patterns using CAD reference data

An image registration approach for inspection of printed circuit patterns which has been validated on a prototype system is described. Theoffline procedure forms, selects, prioritizes, and sorts registration features from CAD-generated reference data. A feature is selected if it satisfies clearance rules that account for the maximum expecteddiscongruence between captured and reference images. The sorting scheme considers the detection complexity of a feature and its distance away from the center of the expected image, since outer features represent potential global distortions better. Theruntime registration procedure detects features and finds the parameters that transform pixels into reference data coordinates and vice versa. We represent robust feature-measurement techniques that offer accurate subpixel localization and verify feature authenticity. We describe an edge-detection technique based on a novel way of authenticating zero-crossings and a method that disqualifies edges detected on defects of the part under inspection.     

基于喷墨打印的可实现敏感材料原位沉积和高温检测的柔性丙酮气体传感器

通过离子交换技术对衬底表面改性,然后喷墨打印掩膜图形,在聚酰亚胺衬底两面分别制备了银叉指电极和加热电阻.通过调节电阻加热器两端的直流偏压,实现25 ℃~280 ℃的控温加热.集成的加热器具有双重功能:纳米ZnO敏感薄膜原位沉积和高温检测.结果表明,该传感器对丙酮气体的灵敏度随温度单调增加(<150 ℃).此外,加热器促进了ZnO敏感薄膜表面丙酮气体分子的解吸,缩短了传感器响应和恢复时间,并减小了初始电阻的漂移.此外,在丙酮检测中,加热器能有效地减少湿度干扰.     

A novel bending microactuator with integrated flexible electro-rheological microvalves using an alternating pressure source for multi-actuator systems

This paper presents a novel bending microactuator with integrated flexible electro-rheological microvalves (FERVs) using an alternating pressure source for multi-actuator systems. The proposed bending microactuator is a fluidic elastomer actuator that has two fluidic chambers inside and can bend with the chamber pressures controlled by the integrated FERVs, each of which has a flexible structure and changes a flow of electro-rheological fluid (ERF) through its viscosity change due to an applied electric field. The utilization of the FERVs in the actuator reduces the overall size, while the benefits of the alternating pressure source are reduction of the number of pipes in a multi-actuator system and removal of the fluid reservoir tank. The mathematical models were demonstrated and utilized for optimizing and designing the dimensions of the actuator to obtain the maximum bending angle, the fast response, and the highest output force. The designed actuator was successfully fabricated using MEMS technologies and experiments were conducted to investigate the bending angle and the response time of the successfully fabricated actuator. The results showed good agreement between the experimental results and the simulation results, which proved the validity of the proposed models. Comparing with the previously proposed microactuator with an FERV, the proposed actuator had 4.5 times larger bending angle. From the results, the optimized actuator showed the feasibility for use in e.g. micro gripper application.

     

Adaptive resonance neural classifier for identification of gases/odours using an integrated sensor array

A new approach to intelligent gas sensor (IGS) design using a classifier based on adaptive resonance theory (ART) artificial neural network (ANN) is presented. Using published data of sensor arrays fabricated and characterised at our laboratory, we demonstrate excellent gas/odour identification performance of our classifier for a 4-gas, 4-sensor system to identify individual gas/odour. Since the ART neural network is a self-organising classifier trained in the unsupervised mode, it avoids the drawbacks associated with static feedforward neural networks trained with a locally optimal backpropagation-type training algorithms applied by researchers in the recent past. The ART neural network offers easy implementability and real time performance in addition to giving excellent classification accuracy as demonstrated by our experiments.     

On the integration of flexible circuit boards with hot embossed thermoplastic structures for actuator purposes

In this work, the integration of flexible printed circuit boards (FPCB) on thermoplastic structures has been studied for the first time. The process was developed with the objective to provide thermal paraffin-based microactuators with local heaters. Essentially, such actuators consist of rigid cavities sealed with flexible membranes deflecting on the melting of enclosed paraffin. Following this concept, 100 μm deep and 2.5 mm wide, circular cavities were fabricated by means of hot embossing of polycarbonate (PC) and joined thermally and by gluing to FPCB or blank polyimide (PI). The bond strength was measured by cavity bursting. The adhesion between PC and PI with thermal bonding was too low to allow any mechanical post processing, whereas gluing facilitated satisfactory joining. Here, the bond strength, measured with cavity bursting was found to depend heavily on the curing conditions. For instance, the use of an intensive UV-exposure could increase the adhesion with a 100% compared to curing with an ordinary UV-lamp. Investigation of channel cross-sections revealed an overall glue thickness of 2–15 μm and that only a minor amount of glue migrated into the channels.Two embossing tools of different resilience were investigated for the embossing of the microstructures. A polydimetylsiloxane (PDMS) mould replicated from SU-8-patterned silicon was compared to a more conventional nickel mould replicated from dry-etched silicon. The embossed samples were inspected in polarised light and it was found that PDMS embossed samples contained no interference fringes. This indicated that ridges, otherwise occurring just outside the cavities, were eliminated in these samples. Electron spectroscopy for chemical analysis (ESCA) revealed a slight difference in silicon contents between surfaces resulting from the two moulds. The nickel embossed surfaces were essentially free from silicon, whereas the PDMS embossed surfaces typically contained a significant concentration of silicon.A couple of actuators with FPCB joined to PDMS embossed PC cavities were fabricated using the developed process. These devices facilitated heating far beyond the melting point of paraffin but failed through paraffin leakage at the bond interface after a small number of activation cycles.     

Electrical characterization of integrated passive devices using thin film technology for 3D integration

With the development of 3D integration technology,microsystems with vertical interconnects are attracting attention from researchers and industry applications.Basic elements of integrated passive devices(IPDs),including inductors,capacitors,and resistors,could dramatically save the footprint of the system,optimize the form factor,and improve the performance of radio frequency(RF) systems.In this paper,IPDs using thin film built-up technology are introduced,and the design and characterization of coplanar waveguides(CPWs),inductors,and capacitors are presented.     

Design of a printed log‐periodic dipole array antenna with high gain for millimeter‐wave applications

In this article, a V‐band printed log‐periodic dipole array (PLPDA) antenna with high gain is proposed. The antenna prototype is designed, simulated, fabricated, and tested. Simulation results show that this antenna can operate from 42 to 82 GHz with a fractional impedance bandwidth of 64.5% covering the whole V‐band (50–75 GHz). The antenna has a measured impedance matching bandwidth that starts from 42 to beyond 65 GHz with good agreement between the experimental and simulated results. At 50 and 65 GHz, the antenna has a measured gain of 10.45 and 10.28 dBi, respectively, with a gain variation of 2.6 dBi across the measured frequency range. The antenna prototype exhibits also stable radiation patterns over the operating band. It achieves side‐lobe suppression better than 17.26 dB in the H‐plane and better than 8.95 dB in the E‐plane, respectively. In addition, the cross‐polarization component is 18.5 dB lower than the copolarization with front‐to‐back ratio lower than 24.1 dB in both E‐ and H‐planes across the desired frequency range. Based on a comparison of performance among the reported work in the literature, we can say that the proposed PLPDA antenna is a proper candidate to be used in many applications at V‐band frequency. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:185–193, 2015.     

Fabrication of a 2-D in-plane micro needle array integrated with microfluidic components using crystalline wet etching of (110) silicon

We propose a two-dimensional (2-D) in-plane micro-needle array with shaft sidewalls aligned parallel to the vertical (111) crystalline plane of (110) silicon. Six types of needle tips with various shapes and tapered angles were fabricated so as to maintain the tip sharpness. Two layers of micro needles (upper and bottom needle arrays) for the 2-D array were realized using simultaneous etching from the front and back sides of (110) silicon. In addition, microfluidic components were embedded in the micro-needle chip to inject or extract biochemical samples. The length of the micro needles was easily extended to 2200 μm, and the insertion forces of the single and arrayed micro needles were evaluated by pricking chicken breast flesh. In case of a micro needle having a tapered angle of 10° and tip end width of 1 μm, the insertion force per needle was as low as 15 mN, which is lower than those reported in previous studies.     

Design and simulation of a new wireless power transfer circuit with a single-stage regulating rectifier for flexible sensor patches

Microsystem Technologies - A new wireless power-transfer circuitry with a single-stage regulating rectifier is designed by this study for wearable flexible sensor patches. The patch is orchestrated...     

结合商业模式探索物联网控制技术课程创新的改革策略

物联网控制技术是物联网系统高效应用的核心技术,商业模式是物联网行业发展的重要驱动,两者之间存在一定的联系.将物联网控制技术和商业模式相结合,有望拓展物联网的创新空间,促进教育和相关产业发展.本文从商业模式与物联网控制技术结合的视角,探讨物联网控制技术课程在理论内容、实验教学、实训方案等方面的改革策略,以提高学生创新和综...     

Design of liveness-enforcing supervisors with simpler structures for deadlock-free operations in flexible manufacturing systems using necessary siphons

Siphons can be used to characterize deadlock states and solve deadlock problems in Petri nets that model flexible manufacturing systems. This paper presents an iterative siphon-based control (ISC) deadlock prevention policy for Petri nets via the combination of mixed integer programming (MIP) and the concept of necessary siphons (NSs). At each iteration in this ISC policy, a maximal deadly marked siphon that is closely related to deadlocks in a Petri net can be conveniently found by an MIP-based deadlock detection method. Then the places in it are classified and an NS is derived from the classified places. For each NS found, depending on its complementary set, the proposed policy adds a proper control place (CP) to make it marked (max-controlled). Moreover, during the ISC procedure, a test for redundant NSs is carried out under a certain condition in order to avoid the addition of the corresponding CPs. The siphon control process proceeds iteratively until the controlled system is live. Compared with the existing approaches, the proposed policy usually leads to a structurally simple liveness-enforcing supervisor by adding as few CPs as possible and achieves better control results. Some examples are introduced to illustrate the proposed approach.     

Design of a controller for a multivariable system with varying parameters using the extended direct Nyquist array

The extended direct Nyquist-array design method is used to design a controller for a gas-turbine-powered marine propulsion plant, the parameters of which are dependent upon load conditions. Non-linear simulation results for the compensated system are presented and compared with the non-linear responses obtained using a conventional controller and also a multivariable gain-scheduled controller developed in previous work.     

Prediction of laser cutting parameters for polymethylmethacrylate sheets using random vector functional link network integrated with equilibrium optimizer

Journal of Intelligent Manufacturing - In this paper, an enhanced random vector functional link network (RVFL) algorithm was employed to predict kerf quality indices during CO2 laser cutting of...