Papers by Keyword: Micro-Fabrication

Abstract: Cysteine and homocysteine are the biological thiols which have an important function in various biochemical processes in our body. Alterations in their level lead to various abnormalities. Therefore, we fabricated a miniaturized platform for capillary electrophoresis that could separate and detect these amino thiols electrochemically. The device was fabricated using conventional photolithography technique on the glass substrate. The microchannel was molded in polydimethylsiloxane with gold electrodes deposited on glass for separation and detection. Based on the amperometric detection, we could detect cysteine in 93 sec while homocysteine was detected in 111 sec.

Abstract: A novel V-shaped microstrip meander-line slow-wave structure was investigated to expand the operating bandwidth. The high frequency characteristics of V-shaped structure and traditional N-shaped and U-shaped structures were analyzed by electromagnetic simulation software HFSS, and the effects of different structural parameters on the high frequency characteristics were studied. The results show that the V-shaped structure provides better performance in operation bandwidth and interaction impedance than traditional structures, and when the dielectric rod replaces the dielectric slab the performance further improves.

Abstract: This work proposes a novel and simple fabrication process of a nickel-copper thermal bimorph actuator. This new fabrication process employs only two-step electroplating technique that is easy, cheap and compatible for various materials. In this study, the total thickness of fabricated cantilever actuator is around 80 μm, i.e. 30±10 and 50±10 μm for nickel and copper, respectively, and its length is equal to 22.5 mm. For actuator’s width, it is varied as 258±7, 351±7 and 447±7 μm. After heating by applying current through the actuator’s structure, the actuator bends up due to the elongation mismatch between copper and nickel elements. It is found that the deflection becomes larger for a narrower actuator. From the experiments, the deflection at current of 2.5A for 258±7 μm wide actuator is approximately equal to 4 mm. In addition, the response of all actuators is faster than 1 Hz. With obtained large deflection and fast response, the fabricated actuators are viable to employ for flow control applications.

Abstract: This paper investigated an novel wireless RF pressure sensor fabricated with SU-8 polymer. The sensor consists of an inductor (L) interconnected with pressure-variable capacitor (C) to form a LC resonant circuit. The fabricated devices is 4 × 3 mm² in size and houses 9 turns of Cu electro-plated coil with inductance of 100 nH. In this system, RF signal was transmitted from external antenna to the fabricated LC resonator. Then RF signal was changed as power of fabricated device via inductive coupling. The external antenna was modulated by resonant frequency of the LC resonator. By detecting this abrupt resonant frequency shift of the device, the pressure change of the device can be measured by wireless method.

Abstract: Polymeric Micro-Fabricated Filters Have Excellent Sieving Properties. Their Identical Properties such as High Surface Porosity and Perfectly Patterned Pore Structure, which Is Combined with Mechanical Strength Make them Ideal for many Applications such as Microorganism Removal, Blood Filtration and Protein Purification. To Improve the Performance of the Micro-Fabricated Filters, we Employed Oxygen Plasma Treatment to Increase the Surface Hydrophilicity and Reduce the Membrane Fouling during Microfiltration. Hydrophilization and Integrity of the Surfaces Were Analyzed by Contact Angle Measurements and Topographic Imaging with an Atomic Force Microscope (AFM). Treatment of Polymeric Membranes with Oxygen Plasma Led to a Stable Hydrophilization and an Increased Surface Roughness. The Filtration Properties of the Modified and Unmodified Membranes Were Examined Using Clay Particles. A Significant Increase in Total Collected Volume of Filtrate Was Observed for the Treated Membranes during Filtration of Simulated Drinking Water Samples Using Clay Suspension.

Abstract: A novel multibranched chromophore containing carbazole moiety，4, 4´, 4´´-tris(9-carbazyl-trans-styryl) triphenylamine (TCSTPA)，was synthesized and characterized by ¹HNMR and elemental analysis. A larger two-photon absorption (TPA) cross section of the chromophore was obtained as high as 2350 GM compared to that of the traditional linear chromophore when pumped by a femtosecond laser at 800 nm. Microstructure based on TPA induced polymerization with a spatial resolution of submicron was fabricated under much lower incident laser power using TCSTPA as a TPA photoinitiator and a multifunctional resin of pentaerythritol triacrylate (PETA) as a polymerizable monomer. The result indicates potential applications of this kind of chromophores with multibranched structural motif in the fabrication of polymer and functional microdevices.

Abstract: Nanomaterials such as 1-dimensional nanowires and nanotubes and 2-dimensional graphene are the promising materials for novel device developments due to their unique physical and chemical properties. For field emission applications, nanomaterials are excellent candidate for an electron source by advantages of their small dimensions and high aspect ratios. In this study, we used GaN nanowires as the nanomaterials synthesized by Vapor-Liquid-Solid method. The field emission devices were then fabricated using the general Si microfabrication techniques. Moreover, the field emission properties of the GaN nanowires were characterized using cold field emission theory. It is demonstrated that the fabrication techniques shown in this study are efficient to fabricate field emission devices using nanomaterials.

Abstract: We studied the effect of geometry on single focusing of particles in the passive microfluidic channels. There is a quantitative analysis of focusing on non-axisymmetric straight channels with two different unique designs as well as curved channels having symmetrical and asymmetrical radius of curvatures in one turn. We found that there is a clear relationship in existence of single line focusing with the degree of non-symmetry in microchannels. One-degree of asymmetry in straight channels does not induce any formation of single focusing, but single line focusing is pronounced by two-degree of asymmetry in straight channels. On the other hand, single line focusing in the curved channels is enhanced with asymmetrical radius of curvatures in one turn. The single line focusing in curved channels is seen at Rep values higher than 1, which gives us better continuous and high-throughput performance. The position of single focused particles in the microchannels is found to be 50 m with respect to the channel wall in the asymmetrical curved microchannels.

Abstract: The main function of the substrate is to sustain and improve the performance of the thin-film. The property and surface configuration of the substrate material have a huge influence on the characteristics of the thin-film. Fabrication of substrate for the micro-transformer can choose a variety of materials, including the silicon, metal, glass, quartz, ceramics, plastics, polymer, etc. Different materials used as substrate have different effects on voltage gain and insertion loss of the transformer. At present, the silicon is used in most cases for its excellent properties. However, it is increasingly found that there exists some problems to gain better performance, such as the parasitic effect. And so, to employ other materials is essential. This paper discusses the effects induced by using different substrate materials. Through the analysis, a general cognition about how to choose the materials can be obtained, which is helpful to design and fabrication of the micro-transformer.

Abstract: The cantilever with a high-aspect-ratio and long probe is a key sub-system of the atomic force microscopes (AFMs) used to measure the surface aspect of the mechanical and optical devices. In this paper, a novel cantilever with a 50μm-length-probe and self-sensing piezoresistor was designed; and based on the micro fabrication technology, the processes were planned. The dynamic and static characteristics of the cantilever were analyzed on theory and finite element method (FEM). The results show that the length of the probe has no effect on the cantilever’s dynamic and static performance.