• Applied Microscopy
• /
• v.40 no.4
• /
• pp.267-270
• /
• 2010

The skin is the largest organ of the integument system whose surface is closely related with many physiological and pathological conditions. Various methods are used to understand the structural and functional status of human skin. We would like to present usefulness of scanning electron microscopic (SEM) observation of skin replica and its significance of training module for a novice. The silicon replicas from several regions of the body (hand, finger, forearm, lip, and face) were casted by applying Exafine$^{(R)}$ mixture. The positive replicas were prepared by applying EPON 812 mixture on negative silicon replicas. Some of the negative silicon replicas were cut with a razor blade and surface profiles were observed. The negative and positive replicas were coated with platinum and were observed under the scanning electron microscope. We could investigate the detailed structures of the human skin surface without any physical damage to the subject. The positive replicas depicted real surface structure of the human skin vividly. The cross sectional view of the negative silicon replicas provided surface profile clearly. The scanning electron microscopic observation of the human skin replicas would be useful to study skin surface structures and to evaluate medical and esthetical applications.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.8 no.2
• /
• pp.94-99
• /
• 2008

The replica of silicone mold which can produce the test samples and the market-displayable products without making expensive metallic patterns is advantageous because it incurs less cost than the ordinary method that manufactures the products from the metallic patterns. However, the production of the products using silicone mold should require a technician with professional knowledge about the metallic patterns every time. Thus we tried to judge whether a forming analysis software for iron molding can be applied to silicon molding in this paper. In other words, this paper suggests a method to use a computer simulator from the designing step of the silicone mold, which is the most important part in making replica using simple silicone molds to the step of pouring the cast. The paper shows that if the know-how of a professional worker is provided in advance, an amateur worker can easily produce silicone molds of the best quality, the defective rate of the products will be decreased, and the replica will have a more complete status. By doing so, we suggested a possibility for reducing the delivery time at the production sites and for improving the product quality.

• Journal of the Korean Ceramic Society
• /
• v.51 no.6
• /
• pp.539-543
• /
• 2014

Foam type porous silicon carbide ceramics were fabricated by a polymer replica method using polyurethane foam, carbon black, phenol resin, and silicon powder as raw materials. The influence of the C/Si mole ratio of the ceramic slurry and heat treatment temperature on the porous silicon carbide microstructure was investigated. To characterize the microstructure of porous silicon carbide ceramics, BET, bulk density, X-ray Powder Diffraction (XRD), and Scanning Electron Microscope (SEM) analyses were employed. The results revealed that the surface area of the porous silicon carbide ceramics decreases with increased heat treatment temperature and carbon content at the $2^{nd}$ heat treatment stage. The addition of carbon to the ceramic slurry, which was composed of phenol resin and silicon powder, enhanced the direct carbonization reaction of silicon. This is ascribed to a consequent decrease of the wetting angles of carbon to silicon with increasing heat treatment temperature.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.351-354
• /
• 2004

This work presents a simple and cost-effective approach for maskless fabrication of positive-tone silicon master for the replica molding of hyperfine elastomeric channel. Positive-tone silicon masters were fabricated by a maskless fabrication technique using the combination of nanoscratch by Nanoindenter ⓡ XP and XOH wet etching. Grooves were machined on a silicon surface coated with native oxide by ductile-regime nanoscratch, and they were etched in a 20 wt％ KOH solution. After the KOH etching process, positive-tone structures resulted because of the etch-mask effect of the amorphous oxide layer generated by nanoscratch. The size and shape of the positive-tone structures were controlled by varying the etching time (5, 15, 18, 20, 25, 30 min) and the normal loads (1, 5 mN) during nanoscratch. Moreover, the effects of the Berkovich tip alignment (0, 45$^{\circ}$) on the deformation behavior and etching characteristic of silicon material were investigated.

• Journal of the Korean institute of surface engineering
• /
• v.37 no.1
• /
• pp.22-27
• /
• 2004

Copper electroforming process has been applied to duplicate Koryo Tripitaka (Taejang'kyong), wooden printing block. Thin copper replica printing plates of 1 mm thickness was successfully manufactured from the printing face (54.5${\times}$25.5 cm) of wooden printing plate. Major processes are (1) silicon rubber replication of the master (2) silvering on silicon rubber (3) copper electroforming (4) separation of copper from the silicon mandrel (5) final coloring by brass plating and trimming. This process has various Potential applications in making thin metallic objects such as plaques, statues, bust and hollow metal objects for jewelry.

• Nuclear Engineering and Technology
• /
• v.56 no.1
• /
• pp.189-194
• /
• 2024

This paper presents a radiation-hardened-by-design preamplifier that utilizes a self-compensation technique with a charge-sensitive amplifier (CSA) and replica for total ionizing dose (TID) effects. The CSA consists of an operational amplifier (OPAMP) with a 6-bit binary weighted current source (BWCS) and feedback network. The replica circuit is utilized to compensate for the TID effects of the CSA. Two comparators can detect the operating point of the replica OPAMP and generate appropriate signals to control the switches of the BWCS. The proposed preamplifier was fabricated using a general-purpose complementary metal-oxide-silicon field effect transistor 0.18 ㎛ process and verified through a test up to 230 kGy (SiO₂) at a rate of 10.46 kGy (SiO₂)/h. The code of the BWCS control circuit varied with the total radiation dose. During the verification test, the initial value of the digital code was 39, and a final value of 30 was observed. Furthermore, the preamplifier output exhibited a maximum variation error of 2.39%, while the maximum rise-time error was 1.96%. A minimum signal-to-noise ratio of 49.64 dB was measured.

• Journal of Sensor Science and Technology
• /
• v.28 no.2
• /
• pp.113-116
• /
• 2019

A three-dimensional porous structure was fabricated by pattern transfer printing for applications of electrodes in gas sensors. To form replica patterns, solutions were mixed with acetone, toluene, heptane, and poly(methyl methacrylate). These replica patterns can also be formed on substrates such as polyimide, polydimethylsiloxane, and silicon. The wide range of line widths from 1 to $5{\mu}m$ was derived from the surface grating patterns of master substrates. The cross-bar pattern with 40 layers showed a thickness of 600 nm. The area of platinum transferred patterns with different line widths was enhanced to $20{\times}25mm$, which is applicable to various electrode patterns of gas sensors.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.22 no.5
• /
• pp.831-836
• /
• 2013

This study demonstrates the process of fabricating patterns using tribonanolithography (TNL),with laboratory-made micro polycrystalline diamond (PCD) tools that are attached to an atomic force microscope (AFM). The various patterns are easily fabricated using mechanical scratching, under various normal loads, using the PCD tool on single crystal silicon, which is the master mold for replication in this study. Then, polydimethylsiloxane (PDMS) replica molds are fabricated using precise pattern transfer processes. The transferred patterns show high dimensional accuracy as compared with those of TNL-processed silicon micro molds. TNL can reduce the need for high cost and complicated apparatuses required for conventional lithography methods. TNL shows great potential in that it allows for the rapid fabrication of duplicated patterns through simple mechanical micromachining on brittle sample surfaces.

• Journal of the Korean Society for Precision Engineering
• /
• v.23 no.7 s.184
• /
• pp.138-145
• /
• 2006

A nanopatterning technique was proposed and demonstrated for low cost and mass productive process using the scanning probe lithography (SPL) and soft lithography. The nanometer scale structure is fabricated by the localized generation of oxide patterning on the H-passivated (100) silicon wafer, and soft lithography was performed to replicate of nanometer scale structures. Both height and width of the silicon oxidation is linear with the applied voltagein SPL, but the growth of width is more sensitive than that of height. The structure below 100 nm was fabricated using HF treatment. To overcome the structure height limitation, aqueous KOH orientation-dependent etching was performed on the H-passivated (100) silicon wafer. Soft lithography is also performed for the master replication process. Elastomeric stamp is fabricated by the replica molding technique with ultrasonic vibration. We showed that the elastomeric stamp with the depth of 60 nm and the width of 428 nm was acquired using the original master by SPL process.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2011.05a
• /
• pp.37.1-37.1
• /
• 2011

Miniaturization of lenses has been widely researched by various scientific and engineering techniques. As a result, micro scaled lens structure could be easily achieved from various fabrication techniques; nevertheless it is still challenging to make nano scaled lenses. This paper reports a novel fabrication method of silicon nanotemplate for nanolens array. The inverse structure of nanolens array was fabricated on silicon substrate by reactive ion etching (RIE) process. This technique has a flexibility to produce different tip shapes using different pattern masks. Once the silicon nano-tip array structure is well-defined using an optimized recipe, it is followed by polymer molding to duplicate nanolens array from the template. Finally, the nanostructures formed on silicon nanotemplate and polymer replica were investigated using FE-SEM and AFM measurements. The nano scaled lens can be manufactured from the same template, also using other replication techniques such as imprinting, injection molding and so on.