• JSTS:Journal of Semiconductor Technology and Science
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• v.7 no.3
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• pp.133-139
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• 2007

Future MEMS systems will be composed of larger varieties of devices with very different functionality such as electronics, mechanics, optics and bio-chemistry. Integration technology of heterogeneous devices must be developed. This article first deals with the current development trend of new fabrication technologies; those include self-assembling of parts over a large area, wafer-scale encapsulation by wafer-bonding, nano imprinting, and roll-to-roll printing. In the latter half of the article, the concept towards the heterogeneous integration of devices and functionality into micro/nano systems is described. The key idea is to combine the conventional top-down technologies and the novel bottom-up technologies for building nano systems. A simple example is the carbon nano tube interconnection that is grown in the via-hole of a VLSI chip. In the laboratory level, the position-specific self-assembly of nano parts on a DNA template was demonstrated through hybridization of probe DNA segments attached to the parts. Also, bio molecular motors were incorporated in a micro fluidic system and utilized as a nano actuator for transporting objects in the channel.

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.146.1-146.1
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.220-223
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• 2005

The rapid prototyping (RP) technology has been advanced for various applications such as verification of design, functional test. However, many RP machines still have low accuracy and limitation of applications for various materials. In this research, a hybrid RP system was developed to improve precision of micro parts. This hybrid system consists of deposition and material removal process by mechanical micro machining to fabricate nano composites using photo-curable polymer resin with various nano particles. In this work, using hybrid RP process with Multi-Walled Carbon Nano Tube (MWCNT) and hydroxyapatite, micro parts were fabricated. The precision of parts was evaluated based on the original CAD design, and to see the effect of nano particles on mechanical properties, tensile strength was measured. From the results of experiments, it was confirmed that the part made by hybrid process had higher precision, and the addition of nano particles improved mechanical properties.

• Journal of the Korean Vacuum Society
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• v.19 no.4
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• pp.300-306
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• 2010

Superhydrophobic micro-nano hybrid structures were fabricated by reactive ion etching of hydrophobic polymer micro patterns using gold nanoparticles as etch masks. Micro structures of perfluoropolyether bisurethane methacrylate (PFPE) were prepared by soft-lithographic technique using polydimethylsiloxane (PDMS) molds. Water contact angles on the surfaces of various PFPE micro structures and corresponding micro-nano hybrid structures were compared to examine the effects of micro patterning and nanostructure formation in the manifestation of superhydrophobicity. The PFPE micro-nano hybrid structures exhibited a very stable superhydrophobicity, while the micro-only structures could not reach the superhydrophobicity but only showed the unstable hydrophobicity.

• Korean Journal of Metals and Materials
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• v.50 no.8
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• pp.591-597
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• 2012

This paper presents regularly micro-textured glass surfaces ensuring the superhydrophobic properties in the Cassie-Baxter regime. The proposed surfaces were fabricated simply and efficiently by filling the glass material into a silicon micro-mold with periodic micro-cavities based on a thermal-reflow process, resulting in a successful demonstration of the textured glass surface with periodically-arrayed micro-pillar structures. The static and dynamic wetting properties of the micro-textured glass surfaces were characterized by measuring the static contact angle (SCA) and contact angle hysteresis (CAH), respectively. In addition, the surface wettability was estimated theoretically based on Wenzel and Cassie-Baxter wetting theories, and compared with the experimental ones. Through the experimental and theoretical observations, it was clearly confirmed that the proposed micro-textured glass surfaces showed the slippery superhydrophobic behaviors in the Cassie-Baxter wetting mode.

• Design & Manufacturing
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• v.16 no.3
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• pp.58-65
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• 2022

Micro-fluidic chip has been fabricated by lithography process on silicon or glass wafer, casting using PDMS, injection molding of thermoplastics or 3D printing, etc. Among these processes, 3D printing can fabricate micro-fluidic chip directly from the design without master or template for fluidic channel fabricated previously. Due to this direct printing, 3D printing provides very fast and economical method for prototyping micro-fluidic chip comparing to conventional fabrication process such as lithography, PDMS casting or injection molding. Although 3D printing is now used more extensively due to this fast and cheap process done automatically by single printing machine, there are some issues on accuracy or surface characteristics, etc. The accuracy of the shape and size of the micro-channel is limited by the resolution of the printing and printing direction or layering direction in case of SLM type of 3D printing using UV curable resin. In this study, the printing direction and thickness of each printing layer are investigated to see the effect on the size, shape and surface of the micro-channel. A set of micro-channels with different size was designed and arrayed orthogonal. Micro-fluidic chips are 3D printed in different directions to the micro-channel, orthogonal, parallel, or skewed. The shape of the cross-section of the micro-channel and the surface of the micro-channel are photographed using optical microscopy. From a series of experiments, an optimal printing direction and process conditions are investigated for 3D printing of micro-fluidic chip.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.245-248
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• 2005

This paper is concerned with manufacturing technology of thin foil tensile specimen using CIP(Cold Isostatic Press) and measurement of precision mechanical property. This thin foil tensile specimen manufacturing technology is a method that can make a metal thin foil specimen for micro tensile testing. We can get a burr free micro metallic thin foil specimen using this technology. For testing mechanical property of this micro thin foil, we use a nano scale material testing machine that was developed by KITECH. In this paper, micro tensile specimens of nickel and copper thin foil are fabricated with CIP and precision mechanical properties of these materials could be measured. We will expect that precision mechanical property of micro/nano material and component. Micro and Nano mechanical property can be measured using this technology and mechanical property data base of micro/nano material and component can be constructed.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.5
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• pp.385-392
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• 2016

Recently in the display industry, demands for high-luminance and resolution of display devices have been steadily increasing. Generally, micro linear patterns are applied to an optical film in order to improve its properties of light. However, these patterns are easily viewed to eyes and moire phenomenon can be occurred. Micro random patterns are proposed as a method to solve these problems, increasing light-luminance and light-diffusion. However, conventional pattern manufacturing technologies have long processing times and high costs making it difficult to apply to large area molds. In order to combat this issue, micro-random patterns are formed by using a roll to plate indentation method along with abrasive paper tools composed of AlSiO2, SiC, and diamond grains. Also, forming properties, such as size and fill-factor of random patterns, are analyzed depending on type, mesh of abrasive paper tools, and indentation forces.

• Current Optics and Photonics
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• v.2 no.6
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• pp.540-546
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• 2018

We propose an implementation scheme for an optical encryption system with hybrid-pattern random keys. In the encryption process, a pair of random phase keys composed of a white-noise phase key and a structured phase key are positioned in the input plane and Fourier-spectrum plane respectively. The output image is recoverable by digital reconstruction, using the conjugate of the encryption key in the Fourier-spectrum plane. We discuss the system encryption performance when different combinations of phase-key pairs are used. To measure the effectiveness of the proposed method, we calculate the statistical indicators between original and encrypted images. The results are compared to those generated from a classical double random phase encoding. Computer simulations are presented to show the validity of the method.

• Journal of Sensor Science and Technology
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• v.17 no.3
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• pp.178-182
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• 2008

Planar type micro catalytic combustible gas sensor was developed by using nano crystalline $SnO_2$ Pt thin film as micro heater was deposited by thermal evaporation method on the alumina substrate. The thickness of the Pt heater was around 160 nm. The sensor showed high reliability with prominent selectivity against various gases(Co, $C_3H_8,\;CH_4$) at low operating temperature($156^{\circ}C$). The sensor with nano crystalline $SnO_2$ showed higher sensitivity than that without nano crystalline $SnO_2$. This can be explained by more active adsorption and oxidation of hydrogen by nano crystalline $SnO_2$ particles. The present planar-type catalytic combustible hydrogen sensor with nano crystalline $SnO_2$ is a good candidate for detection of hydrogen leaks.