Patterned electrodeposition of interconnects using microcontact printing

Microcontact printing combined with electroless deposition is a potential low cost technique to make electrical interconnects for opto-electronic devices. Microcontact printed inhibitors locally prevent electroless deposition resulting in a pre-defined pattern of metal tracks. The inhibition of electroless Ni deposition on Pd-seeds and on indium tin oxide (ITO) by self-assembling molecules (SAM) was investigated. Polarisation measurements and transients show that on Pd seeds for electroless deposition, thiol-compounds inhibit the oxidation of the reducing agent, hypophosphite, in the electroless Ni bath. Cyclic voltammetry suggests that the inhibition is due to adsorption of the inhibiting molecules on active sites of the Pd-seeds only or as a SAM on the entire Pd seeds depending on the thiol-compound used. Polarization measurements show that after a pre-treatment in nitric acid hexadecylamine (HDA) is able to inhibit Ni electrodeposition on ITO. It was found that the pre-treatment activated ITO for Ni electrodeposition. Adsorbed HDA increases the crystallization overpotential for Ni electrodeposition by approximately 100 mV.     

Screen printing of silver nanoparticle suspension for metal interconnects

Silver nanoparticle suspensions were synthesized by chemical reduction method using a formaldehyde reductant. Polyvinyl pyrrolidone (PVP) of two different molecular weights (M.W.=8,000 and 29,000) was used as a stabilizer for the suspensions. PVP of a smaller molecular weight could produce silver suspensions of nanoparticle size around 20 nm. Water-based conductive silver inks with different silver concentrations were prepared and tested for suitability for screen printing. We have successfully printed silver metal lines on glass substrates using a 400 mesh screen-mask with 60wt.% silver ink prepared in this study. Curing at a low temperature of 200 °C for an hour was found sufficient to reach the lowest resistivity value with the synthesized ink. For a line with a width and thickness of 0.5 mm and 2.12 μm, respectively, it exhibited a resistivity of 3.3×10⁻⁵ Ω·cm, which could serve as conducting lines for various electronic applications.     

Temperature dependence of the electrical transport properties in few-layer graphene interconnects

We report a systematic investigation of the temperature dependence of electrical resistance behaviours in tri- and four-layer graphene interconnects. Nonlinear current–voltage characteristics were observed at different temperatures, which are attributed to the heating effect. With the resistance curve derivative analysis method, our experimental results suggest that Coulomb interactions play an essential role in our devices. The room temperature measurements further indicate that the graphene layers exhibit the characteristics of semiconductors mainly due to the Coulomb scattering effects. By combining the Coulomb and short-range scattering theory, we derive an analytical model to explain the temperature dependence of the resistance, which agrees well with the experimental results.     

Simultaneous synthesis and patterning of graphene electrodes by reactive inkjet printing

Reactive inkjet printing (RIP), a single-step process for micro-chemical reactions and arbitrary patterning, was applied to fabricate reduced graphene oxide (RGO) films. Graphene oxide was successfully reduced to RGO through the RIP process. The printed RGO films showed moderate conductivity and transmittance. LED operation with reactive inkjet-printed RGO electrodes was also demonstrated. By utilizing this printing method, we can drop additional reducing steps and obtain directly patterned RGO instead, which suggests that reactive inkjet-printed RGO would be feasible for use as transparent electrodes to replace indium tin oxide in displays and photovoltaic devices.     

改性氧化石墨烯膜处理印染废水的能力与机理

利用改性氧化石墨烯膜处理高色度、高毒性工业染料废水。使用硫脲（TU）对氧化石墨烯（GO）进行交联,以m(TU):m(GO)=0.5,反应温度80 °C,反应时间1 h的TU-GO纳米片为原料,在聚醚砜微滤膜（0.22 μm）上沉积,当负载量为238.73 mg/m2时,对甲基橙、罗丹明B、亚甲基蓝的截留率为94.01%、87.07%和99.67%;为优化对罗丹明B的分离效果,使用硫脲（TU）和氯化胆碱（ChCl）组成低共熔溶剂(DES)制备改性氧化石墨烯膜：m(TU):m(ChCl)=2:1,改性时间1 h。改性氧化石墨烯膜未对甲基橙、亚甲基蓝原有的高截留率造成影响,截留率分别为93.95%,99.24%;对罗丹明B截留率提升至99.16%。另对TU交联过程中对GO的还原机理和增稳机理做出分析。     

3D打印制备三维石墨烯及其在水处理中的应用

石墨烯作为一类新型纳米材料,具有对水中各类污染物良好的吸附去除性能,但石墨烯纳米粉末态的性状使其在使用后难以从溶液中分离出来而造成二次污染。因此构建大体积的三维石墨烯结构,可以有效弥补水处理中纳米材料难以分离的问题。本文介绍了如今常用的三维结构制备方法,如模板法、自组装法等,但这些方法通常步骤烦琐、影响因素及所需条件较多等,在过程中易产生结构缺陷,从而影响制得的三维结构的力学性能。文中指出,3D打印法通过计算机数据调控,具有操作简便、结构设计精准、批量制备的优点,可制备出优良的三维结构体,并可通过对浆料组分的灵活调控进行改性或增加其力学性能。综上所述,配置满足3D打印黏度要求的浆料,并使制得的三维结构具备一定要求的力学性能,充分利用其精密的规模化生产,是使3D打印三维石墨烯适用于水处理的关键所在。     

用于喷墨印花染料纯化的自组装GO/TiO2复合纳滤膜的制备

数码喷墨打印技术对墨水高纯度和低含盐量要求,不断促使染料纯化技术的开发与研究。基于氧化石墨烯(GO)/纳米二氧化钛(TiO₂)自组装的纳滤膜材料的开发,探究了纳米TiO₂颗粒尺寸和与GO共混比例,所获最优GO/TiO₂复合纳滤膜中TiO₂颗粒尺寸为60 nm,与GO共混比例为1∶1。其纯水通量为10.69 L/(m²·h·bar),对NaCl和Na₂SO₄的截留分别为12.6%和15.7%,对铬黑T、刚果红和考马斯亮蓝R的截留均高于99%。采用自制的连续恒容渗滤装置对粗品墨水进行染料脱盐浓缩的实验,所获染料的浓度由最初的2.0 g/L浓缩至9.74 g/L,NaCl和Na₂SO₄浓度则由起始10 g/L分别下降至5.3 mg/L和11 mg/L,满足数码印花对墨水高纯度以及低盐度的要求。     

Micro-scale fracture toughness of textured alumina ceramics

Enhanced fracture resistance of textured alumina is ascribed to crack deflection along grain boundaries. In this work, we quantify and compare the micro-scale fracture toughness of textured alumina grains and grain boundaries by micro-bending tests. Notched micro-cantilevers were milled from single alumina textured grains (perpendicular to the [0001] direction) and across several textured grains (along the [0001] direction), using a focused ion beam technique. Bending tests were performed with a nanoindenter. A shape function for notched pentagonal-shaped cantilevers was developed using finite element analysis. The critical stress intensity factor at the notch tip was determined based on the measured fracture loads. The micro-scale fracture toughness of the textured alumina grain boundaries (2.3 ± 0.2 MPa m^1/2) was about 30% lower than that of the grains (3.3 ± 0.2 MPa m^1/2). These findings at the micro-scale are paramount for understanding the macroscopic fracture behaviour of textured alumina ceramics.     

Robust and conductive mesoporous reduced graphene oxide-silica hybrids achieved by printing and the sol gel route

Reduced graphene oxide (rGO) scaffoldings are used as templates to create lightweight 3D rGO/silica and rGO/silico-aluminate hybrids by a simple impregnation route and the sol-gel method. The printed rGO assemblies are infiltrated by the corresponding alkoxide precursor solution and gelled by exposure to ammonia vapours, producing an hybrid replica of the rGO structure. The hybrids show a significant prevalence of mesopores, with total porosity above 94 %, density of ～ 0.1 g?cm^?3 and high specific surface area (≥ 190 m²?g^?1). As a result, the 3D composite materials show enhanced water adsorption capacity and hydrophilicity, display compressive strengths in the range 0.1 – 0.4 MPa, which scale with the proportion of silica (or Al-modified silica) on the hybrid scaffold, and electrical conductivities are above 60 S?m^?1. These properties are very attractive for applications in the removal of pollutants, water filtering, catalysis, drug delivery, or energy production and storage.     

微尺度效应和壁面滑移对微挤出成型的影响分析

研究分析了聚合物在微细管道中的微尺寸效应以及壁面滑移机理,在采用数值模拟软件Polyflow的基础上分析了黏度和壁面滑移对聚合物微尺寸流动的影响,并结合不同的边界条件分析了机头压缩段长度对制品变形的影响。结果表明,有壁面滑移条件下,熔体流动阻力减小,速度分布更加均匀,制品变形较小。     

燃料电池的微尺度测试技术

随着燃料电池体积的微小化,传统的测试技术已经不再适合微型燃料电池某些参数的测试。在这种情况下,基于微机电系统的微尺度测试技术被逐步引入燃料电池的测试中。本文对燃料电池的温度、湿度及燃料浓度等参数的微小型测试技术进行了回顾,同时也对引入显微镜等设备的微型燃料电池可视化系统进行了讨论。最后对燃料电池的微尺度测试技术发展前景进行了分析。     

微型有机化学实验教学的改革与实践

通过对微型有机化学实验的优势进行分析,探讨了微型有机化学实验在教学实践中存在的问题和对策,初步摸索出微型有机化学实验教学改革的课程设置原则和方案。通过合理地设置常量和微量化实验课程,在教学实践过程中把基本操作实验和以及综合设计研究型实验很好的衔接起来。不仅能使学生掌握基本的实验操作技能,还提高了学生对有机化学实验的兴趣和学习积极性,培养了进一步综合设计研究的能力,树立了环保意识和社会责任感。     

Use of carbon nanotubes for VLSI interconnects

The requirements for using carbon nanotubes as interconnects in future integrated circuits are defined. Growth techniques and some methods of their characterisation are described. The need to grow nanotubes on conducting metal substrates is pointed out and this effort is starting.     

Crosstalk analysis of carbon nanotube bundle interconnects

ABSTRACT: Carbon nanotube (CNT) has been considered as an ideal interconnect material for replacing copper for future nanoscale IC technology due to its outstanding current carrying capability, thermal conductivity, and mechanical robustness. In this paper, crosstalk problems for single-walled carbon nanotube (SWCNT) bundle interconnects are investigated; the interconnect parameters for SWCNT bundle are calculated first, and then the equivalent circuit has been developed to perform the crosstalk analysis. Based on the simulation results using SPICE simulator, the voltage of the crosstalk-induced glitch can be reduced by decreasing the line length, increasing the spacing between adjacent lines, or increasing the diameter of SWCNT.     

声场强化微小流化床流动特性研究

在内径4.3mm微小流化床中,考察了声场对FCC及石英砂颗粒流化质量的影响。重点讨论了声压级与频率对微小流化床最小流化速度的影响。结果表明,声场能改善微小流化床流化质量。尤其对于51μm石英砂颗粒,声场可以使其消除沟流,实现稳定流化。声压越大,声场对微小流化床流化质量改善越明显。最小流化速度随声压增高呈单调下降趋势。相同声场条件下,声波对微小流化床最小流化速度数值降低幅度大于大尺度流化床。声场对微小流化床最小流化速度的影响存在最佳频率。但不同颗粒的最佳频率不同。内径4.3mm流化床,51,67,83μm石英砂颗粒与83μmFCC颗粒对应的最佳频率分别为90,90,140和140Hz。在一定的声压与频率下,声场可以降低最小流化速度约9%～21%。对于微小流化床,床径越小,则床层空隙率越大,越有利于实现外场强化,最小流化速度的降低幅度也逐渐增大。     

Micro-scale fluid model for drying of highly porous particle aggregates

A discrete three-dimensional model for the fluid flow and phase transition at the microscopic scale during convective drying of highly porous particle aggregates has been developed. The phase distributions are described by time-dependent cell volume fractions on a stationary cubic mesh. The solid phase volume fractions are computed from an arbitrary collection of spherical primary particles generated by gravitational deposition using the discrete element method. The volume of fluid method is used to track the liquid–gas interface over time. Local evaporation rates are computed from a finite difference solution of a vapor diffusion problem in the gas phase, and the liquid–gas interface dynamics is described by volume-conserving mean curvature flow, with an additional equilibrium contact angle condition along the three-phase contact lines. The evolution of the liquid distribution over time for different wetting properties of the solid surface as well as binary liquid bridges between solid particles are presented.     

Micro-scale modelling of substrate removal kinetics in multicomponent fixed-film systems

Modelling of fixed-film reactors, as for suspended growth systems has to account for all the major components and biochemical processes responsible for the removal of substrate. Traditionally fixed-film reactors are viewed as two-component (substrate/biomass) systems interacting with the governing effect of molecular diffusion. Recent developments however have shown the importance of viability and product formation in the modelling of biological systems. This paper emphasizes these two new parameters and evaluates the kinetic relationships between the bulk substrate concentration and biofilm composition as it affects substrate removal and residual product formation.     

微尺度下塑料微管气辅挤出成型的模拟及分析

在微尺度下,为了保证塑料微管成型的精度,必须考虑熔体的可压缩性对塑料微管成型的影响.针对微尺度下熔体的可压缩性,对塑料微管的双层气垫层气辅挤出成型的过程进行了有限元数值模拟,并且与不可压缩熔体所得到的数值分析的结果进行了对比.对壁厚为1 mm以下的塑料微管的挤出过程中熔体的密度、微管的内半径、熔体的壁厚、温度、X及Y速...     

Jet printing

Ink jet printers, some capable of producing a full colour gamut, are now widely used as output devices for computer-generated design work. Some advances have been made in the application of these ink jet paper printing technologies to textile printing, mainly for carpets. This review describes the principal jet systems that have been developed commercially for both textile and reprographic uses, and indicates areas in which the ink jet principle appears to have future potential. The physical and chemical requirements of the inks used in the different systems, as well as the possible pretreatment of the substrate to improve ink receptivity and the durability of the print, are also discussed.