Resin-bonded NdFeB micromagnets for integration into electromagnetic vibration energy harvesters

A micromachining technique is presented for the fabrication of resin-bonded permanent magnets in the microscale. Magnetic paste is prepared from NdFeB powder and an epoxy resin, filled into lithographically defined photoresist molds or metal molds, and formed into resin-bonded magnets after curing at room temperature. A coercivity of 772.4 kA/m, a remanence of 0.27 T, and a maximum energy product of 22.6 kJ/m³ have been achieved in an NdFeB disk micromagnet with dimensions of Φ200 μm×70 μm. Based on the developed micro-patterning of resin-bonded magnets, a fully integrated electromagnetic vibration energy harvester has been designed and fabricated. The dimensions of the energy harvester are only 4.5 mm×4.5 mm×1.0 mm, and those of the micromagnet are 1.5 mm×1.5 mm×0.2 mm. This microfabrication technique can be used for producing permanent magnets tens or hundreds of micrometers in size for use in various magnetic devices.     

电镀废水微机自动处理系统的实现

本文介绍了电镀污水处理系统的组成及工作原理,给出了基于C8051F单片机监测控制系统的硬件及软件实现方案,该设计能够准确控制电镀污水处理的质量,运行结果表明该设计方案合理可靠.     

电镀废水微机自动处理系统的实现

本文介绍了电镀污水处理系统的组成及工作原理,给出了基于C8051F单片机监测控制系统的硬件及软件实现方案,该设计能够准确控制电镀污水处理的质量,运行结果表明该设计方案合理可靠。     

Alternative resist adhesion and electroplating layers for LIGA process

 The fabrication of high aspect ratio microstructures using the X-ray lithography and electroplating step of the LIGA process requires, that the metal layer on the substrate (plating base) enables a flawless resist adhesion and provides a high conductivity for the following electroplating process. In addition, a flawless metal adhesion after electroplating has to be ensured. Typically metal layers of titanium, but also of copper and gold are used. In case of higher structures, fluorescence radiation generated in the metal layer during exposure reduces the bond strength between the resist and the adhesion layer [7]. Since the fluorescence probability decreases with a decreasing atomic number, the suitability of conductive carbon as the plating base was investigated and compared to results achieved with titanium. The resist adhesion was increased tremendously on the carbon layer but the metal adhesion is insufficient. Therefore, platinum islands were deposited on the conductive carbon to facilitate good metal adhesion. The resulting resist adhesion was still superior compared to titanium. In addition, metal adhesion was achieved on these layers.     

Embedded printing trace planning for aluminum droplets depositing on dissolvable supports with varying section

Droplet-based 3D printing is a promising method to manufacture thin-walled parts with high-quality cavity surfaces of a complex geometry by virtue of dissolvable supports. However, conventional equispaced droplet scanning strategies cannot be used for dissolvable support assisted droplet printing that involves more complex impingement conditions, particularly when the dissolvable supports possess varying sections. This paper investigates the printing strategies for aluminum droplets depositing on dissolvable support that possesses preset dimensions, inclined surfaces and corners. Experimental and numerical results show that: (1) printing orientation on the oblique surfaces of dissolvable supports significantly influences the formation of hole-defects; (2) the printing strategy for corners should be specially adjusted to minimize defects. Moreover, the droplet scanning spacings on the support surfaces with preset shape and dimensions are elaborately regulated according to four different cases. Finally, the fabrication experiments of aluminum horns are performed to further examine the formability of the established droplet scanning strategies. The density of the printed horn is measured to be ~98% using the standard Archimedes method, and the corresponding industrial CT scanning results also verify a porosity-free inner structure. The cavity surfaces of the horn are smooth without obvious defects, and the average surface roughness of the inner surface is ~Ra 4.2 μm (only 0.53% of the droplet diameter). These measurement results indicate that the proposed strategies can effectively eliminate hole-defects that are commonly seen in equispaced printing.     

Fabrication of bio-microelectrodes for deep-brain stimulation using microfabrication and electroplating process

This paper presents a novel bio-microelectrode structure for deep-brain stimulation in neural disorder treatment and a method for connecting PtIr₁₀ microwires onto this microelectrode. The microelectrode is consisted of four stimulation sites fabricated by microfabrication process and two recording sites formed by encapsulation technique. After Si-based microelectrode is fabricated through microfabrication process, electroplating is used to connect microwires to the microelectrode through a Pt film electroplated on the microwires that is fixed in the grooves of the microelectrode. Scanning electron microscopy revealed that the microwire was connected tightly to the microelectrode by electroplating, and the tensile strength of the microwire connection reached up to 0.375 MPa when the thickness of the Pt film was 3 μm and above. Cyclic voltammograms showed that the microelectrode and the electroplated connection had fine electrochemical stability. The results indicated that the electroplating could be used as an effective method for connecting PtIr₁₀ microwires with Pt film microelectrode in deep-brain stimulation.     

Magnetic flux memory effect using a magnetostrictive material-shape memory piezoelectric actuator composite

A magnetostrictive-shape memory piezoelectric material composite is proposed to realize a magnet field memory effect. An imprint electrical field enables a shape memory piezoelectric actuator, and the shape memory effect maintains a certain permeability of the magnetostrictive materials. A new magnetic flux memory effect is generated using a composite of the magnetostrictive-shape memory piezoelectric actuator and a permanent magnet. This magnetic flux memory effect can be operated with a pulsed voltage to the shape memory piezoelectric actuator, so that no energy is consumed to maintain a certain magnetic effect.     

A flip-chip LIGA assembly technique via electroplating

 A novel flip-chip assembly technique by means of electroplating at a low processing temperature has been developed. Mesoscopic gears, made of nickel with 1500 μm in diameter and 250 μm in height, have been bonded to glass substrate. The bonding process is conducted by nickel electroplating at 50 °C with a current density at 53.3 A/m². The nickel electrolyte is found to penetrate about 100 μm from the perimeter to the center of the gear and form a good bond. This process can be applied to the integration of high-aspect-ratio microstructures with substrates that have pre-fabricated microelectronics massively and in parallel. As such, it provides a powerful way to achieve the integration of meso- and microscopic electromechanical systems. Received: 7 July 1999/Accepted: 30 June 2000     

Fabrication of metallic micromirror using electroplating technology

A nickel micromirror array was designed and successfully fabricated using a thick photoresist as a sacrificial layer and as a mold for nickel electroplating. It was composed of two address electrodes, two support posts and a nickel mirror plate. The mirror plate, which is supported by two nickel posts, is overhung about 10???m from the silicon substrate. The nickel mirror plate is actuated by an electrostatic force generated by electrostatic potential difference applied between the mirror plate and the address electrode. Optimized fabrication processes have been developed to reduce residual stress in mirror plate and prevent contact between the mirror plate and the substrate, which ensure a reasonable flat and smooth micromirror for operation at low actuation voltage.     

基于CPLD的电子存包系统的设计与实现

介绍了基于CPLD的刷卡式电脑联网集控型自动存包系统的设计,并对系统的软硬件构成、CPLD内部逻辑设计、工作原理等进行了详细说明。该系统速度快、安全性好、可靠性高,而且具有操作简便、查询快捷、便于实时监控等特点。     

Fabrication of metallic micromirror using electroplating technology

A nickel micromirror array was designed and successfully fabricated using a thick photoresist as a sacrificial layer and as a mold for nickel electroplating. It was composed of two address electrodes, two support posts and a nickel mirror plate. The mirror plate, which is supported by two nickel posts, is overhung about 10 μm from the silicon substrate. The nickel mirror plate is actuated by an electrostatic force generated by electrostatic potential difference applied between the mirror plate and the address electrode. Optimized fabrication processes have been developed to reduce residual stress in mirror plate and prevent contact between the mirror plate and the substrate, which ensure a reasonable flat and smooth micromirror for operation at low actuation voltage.

     

Creating low-impedance tetrodes by electroplating with additives

A tetrode is a bundle of four microwires that can record from multiple neurons simultaneously in the brain of a freely moving animal. Tetrodes are usually electroplated to reduce impedances from 2-3 MΩ to 200-500 kΩ (measured at 1 kHz), which increases the signal-to-noise ratio and allows for the recording of small amplitude signals. Tetrodes with even lower impedances could improve neural recordings but cannot be made using standard electroplating methods without shorting. We were able to electroplate tetrodes to 30-70 kΩ by adding polyethylene glycol (PEG) or multi-walled carbon nanotube (MWCNT) solutions to a commercial gold-plating solution. The MWCNTs and PEG acted as inhibitors in the electroplating process and created large-surface-area, low-impedance coatings on the tetrode tips.     

High aspect ratio micromolds for the electroplating of micro electro discharge machining tools

A new approach using micro systems technology for the fabrication of micro electro discharge machining tool electrodes using a combination of positive and negative photoresist fabricated with near UV-lithography as high aspect ratio micromolds was developed. Micromolds with heights varying from 200 to 650 μm and an aspect ratio of up to 26:1 were fabricated using SU-8?, a negative photoresist, as a micromold for the electrodeposition of the micro tool electrodes. Besides serving as a micromold, SU-8? is also used as an insulator to protect the sidewalls of the tool electrodes from corrosions. The fabrication of the SU-8? micromold was optimized to avoid cracks and delaminations. In the experiments, electrodes made of Cu, WCu, and CoFe were deposited into these High Aspect Ratio Micro Structure Technology (HARMST) micromolds. Furthermore, the process technique for electroplating in deep micromolds is discussed in this paper.     

A genetic algorithm for a single hoist scheduling in the printed-circuit-board electroplating line

In this paper, the problem of determining cyclic schedules for a material handling hoist in the printed-circuit-board(PCB) electroplating line is considered. The objective of this research is to determine an optimal simple-cycle schedule of the hoist which in turn maximizes the line throughput rate. Previous approaches to the cyclic hoist scheduling problem are all mathematical programming-based approaches to develop cyclic schedules(Mixed Integer Programming, Linear Programming based Branch and Bound, Branch and Bound Search Method and so on). In this paper, a genetic algorithm-based approach for a single hoist scheduling in the PCB electroplating line is described. Through an experiment for the well known example data, the proposed algorithm is shown to be more efficient than the previous mathematical programming-based algorithm.     

Application of electroplating in MEMS-micromachining exemplified by a microrelay

 Electrodeposition processes were proposed for the fabrication of micro-electro-mechanical systems (MEMS) long time ago. Patterned layers of nickel, nickel alloys, gold alloys, silver and copper are used to realize micro switches, relays, valves, pumps, coils and gyroscopes. The metal layers have to meet the highest requirements on homogeneity, as well as on mechanical, electric or magnetic characteristics. The application of microelectroplating has to cope with specific effects influencing the electroplating conditions in the micrometer range. So, many efforts concentrate on the control and standardisation of microelectroplating processes. The suitability and application of electroplating methods will be exemplified by two concepts of a microrelay assigned for current loads of up to several amperes. The development of these microrelays is object of the project “MikroRel”, partially funded by the German ministry for education and research (BMBF).     

Fabrication of metallic microstructures by electroplating usingdeep-etched silicon molds

A new technology is presented here to fabricate three-dimensional micromachined metal structures. The microstructures are manufactured by electroplating in deep-etched silicon structures followed by a separation from their mold. Up to 140-μm-deep silicon structures with vertical sidewalls are realized by an anisotropic plasma etching process producing the mold for electroplating. An etching gas mixture of SF_6s and CBrF₃ is used to achieve both an anisotropic etching behavior by protective film formation of CF₂ -radicals and high etching rates. The anisotropy is due to photoresist masking, which enhances the polymer formation. The vertical trenches are electroplated from the trench base filling the structures uniformly to the substrate surface. By avoiding overplating across the whole substrate the resulting structures are suitable for micromechanical devices. If needed, released microstructures from the silicon mold can be obtained by direct lift-off     

Flip chip electrical interconnection by selective electroplating and bonding

This work presents a parallel electrical interconnection process by means of flip-chip, selective electroplating and bonding. The electrical interconnection lines are built on a glass substrate made of 500/2000 Å of Cr/Au with 3150 m in length and 10 m in width. Two silicon chips are processed as the device chips to be electrically interconnected. It has been demonstrated that 98 out of 102 interconnects are established in parallel with a successful rate of 96% and the average resistance of the electroplating bond is 12 . This process has potential applications in replacing the conventional, serial wire bonding or tape automated bonding (TAB) process for massive interconnection requirements in IC or MEMS devices. Reliability test is also performed by putting the interconnects into boiling liquid nitrogen (–195 °C) repeatedly. It is found that 100% of the interconnects survive after 2 cycles of the quenching process.The author would like to thank Mr. Ron Wilson for taking SEM pictures. This project is supported in part by a NSF award (DMI-0096220) and a Sandia National Laboratory grant. This paper was presented at the Fourth International Workshop on High Aspect Ratio Microstructure Technology HARMST 2001 in June 2001.     

基于磁敏感的磁兼容金属植入物的正对比磁共振成像

在磁共振成像中,磁共振兼容金属植入物的磁化率较高,从而导致图像信号的缺失与失真,严重影响装置的精准定位和评估。2014年,有学者提出一种正对比成像方法,利用偏移180°回聚脉冲的自旋回波序列,结合特有的定量磁化率重建算法,重建出近距离放射颗粒的正对比图像。在此基础上,文章对该方法进行进一步扩展,在西门子3 T人体磁共振成像系统上,将该方法应用到活检针和过滤器等较大金属介入装置的正对比成像。活检针和过滤器水模磁共振成像实验结果表明,这种正对比成像方法可应用于较大的金属装置,有效地抑制了金属伪影,获得清晰的正对比图像,提高了装置定位和评估的精准度。     

肿瘤热化疗用磁性聚合物微球的制备及表征

以磁性四氧化三铁(Fe3O4)纳米粒子和可降解聚合物聚乳酸-羟基乙酸共聚物为原料,采用乳化-溶剂挥发法制备获得磁性聚合物微球.通过傅里叶红外光谱、热失重曲线、透射电子显微镜、振动样品磁强计对所制备的磁性聚合物微球的各项性能进行表征,并利用高频磁感应设备测定磁性聚合物微球的磁感应加热性能.结果表明,所制备的两种磁性聚合物微球中Fe3O4纳米粒子的含量分别为10.1％和18.8％,其比饱和磁化强度分别为2.3 emu/g和6.8 emu/g;在高频磁场作用下,8 min内升温分别可达到9℃和16.5℃,完全满足肿瘤磁热疗的升温需求,在肿瘤磁热疗及热化疗结合治疗中有着很好的应用潜力.