Papers by Author: Yung Kang Shen

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Authors: Yung Kang Shen
Abstract: This paper reports a simple and novel procedure for mold insert of microlens array. The micro injection molding (MIM) and micro injection-compression molding (MICM) are used to replicate the microlens array. The 200×200 arrays of molded microlens, with a diameter of 150 $m, a pitch of 200 $m and a sag height of 11.236 $m have been successfully fabricated. The average surface roughness of the Ni mold insert is 6.916 nm. The average surface roughness of the molded microlens array is 4.608 nm for MIM and 4.555 nm for MICM. The complete fabrication process of mold insert is executed at room temperature and low pressure for this paper.
Authors: Yi Lin, Chiung Fang Huang, Hsin Chung Cheng, Yung Kang Shen
Abstract: Hydroxyapatite (HA) coating of hard tissue implants is widely employed for its biocompatible and osteoconductive properties as well as its improved mechanical properties. In this study, a novel micro-blasting process has been used to successfully modify a titanium alloy substrate with a HA treatment using a dopant/abrasive regime. The impact of a series of apatite abrasives, was investigated to determine the effect of abrasive particle size on the surface properties of both micro-blasting (abrasive only) and continuous (HA/abrasive) treatments. The resultant HA treated substrates were compared to substrates treated with abrasive only (micro-blasted) and an untreated Ti. The HA powder, apatite abrasives and the treated substrates were characterized for chemical composition, coating coverage, crystalline and topography. The results show that the surface roughness of the HA blasted modification was affected by the particle size of the apatite abrasives used. This study demonstrates the ability of the continuous process to deposit HA coatings with a range of surface properties onto Ti alloy substrates. The ability of the continuous technology to offer diversity in modifying surface topography offers exciting new prospects in tailoring the properties of medical devices for applications ranging from dental to orthopedic settings.
Authors: Chiung Fang Huang, Jeol Long Lee, Yung Kang Shen, Chi Wei Wu, Yi Lin, Sung Chih Hsu, Ming Wei Wu, Chung Yu Kao
Abstract: This study demonstrates the replication property and surface roughness for metal micro-mold that combines the replica molding (REM) and electroforming techniques. The micro-mold firstly uses the silicon wafer to fabricate the master mold by UV-LIGA method, and then uses the sputtering method to sputter the Ni element as the seed layer on the surface of master mold. The electroforming method manufactures the Ni mold insert from the master mold with seed layer. Finally, this study uses the PDMS material to replicate the micro-feature from the Ni mold insert by replica molding. This study indicates the replication property and surface roughness of different micro-feature shapes and sizes (concave and convex) for Ni mold insert and molded PDMS.
Authors: Yung Kang Shen, H.J. Chang, L.H. Hung
Abstract: This paper presents the application of microstructure replication of lightguiding plate for micro injection compression molding (MICM). The lightguiding plate is applied on LCD of two inch of digital camera. Its radius of micro-structure is from 100μm to 300μm by linearity expansion. The material of lightguiding plate is PMMA. This paper discusses the replication properties for different process parameters by single-parameter method for micro injection compression molding. The important process parameters of replication properties are the mold temperature, compression distance and melt temperature in micro injection compression molding. The mold temperature is the most significant factor of replication properties of microstructure of lightguiding plate for micro injection compression molding.
Authors: Jeou Long Lee, Chao Hsien Ho, Yi Lin, Yung Kang Shen
Abstract: In this work, skeletons of micro aerial vehicle are fabricated by precision injection molding. The Taguchi method is adopted to identify the important factors that govern the shrinkage of MAV skeletons. The results indicate that the most significant factor in the shrinkage of a skeleton formed by precision injection molding is the mold temperature.
Authors: Fwu Hsing Liu, Wen Hsueng Lin, Yung Kang Shen, Jeou Long Lee
Abstract: This paper presents a layer additive method, ceramic laser curing, to form a ceramic part with inner channel features, by which silica powder is bonded by curing effect under disposal of a 20W CO2 laser. This process includes four steps: making slurry by mixing a binder with ceramic powder, paving the slurry on the surface of a platform, scanning the paved slurry layer via laser beam, removing the un-cured slurries from the solidified ceramic component. This process needed only low laser power to build ceramic parts by using “curing effect”. The deflection and shrinkage of ceramics could be decreased, also the distortion due to post sintering process was avoidable. The inner channel structures were support by ceramic slurries to avoid the sagged deflection and to maintain the dimensional accuracy. The maximum flexural strength of the cured specimen was 4.7 MPa. This process has potential to fabricate inner complex ceramic components for industrial applications.
Authors: Chih Wei Wu, Chih Heng Chi, Hung Yin Tsai, Yung Kang Shen
Abstract: This paper presents an innovative fabrication of a large-area silicon mold with microstructures. Conventional techniques capable of manufacturing a large size mold pose severe challenges in making microstructures. In contrast, semiconductor process is limited in its wafer scale. This paper shows a new approach to achieve a large beyond-wafer-size silicon mold with alignment microstructures using two-direction passive alignment recombining techniques. Anisotropic bulk-micromachining technique, laterally joined of (111) silicon crystal planes, passive-alignment methods are the key to fabricate a large-area silicon mold. The area of each small silicon plate is 2.9cm2. Therefore, four small silicon plates with microstructures were recombined as a large-area square silicon mold. The optical fibers were placed into V-grooves on small silicon plates to make sure of microstructures alignment, minimum tilting and rotation angles between plates during the recombining process. The gap, height difference, and aligning accuracy of microstructures between joined silicon plates were able to achieve 8μm, 0.902μm and 20μm, respectively. Moreover, the rotation and tilting angles could be lowered to 0.0622 degree and 0.002 degree, respectively. Microstructures on the large-area silicon mold are faithfully reproduced by polydimethylsiloxane (PDMS). Finally, a 16.8 cm x 12.6 cm silicon mold was fabricated using twelve 4.2cm x 4.2cm silicon plates. It is believed that the novel technique will give an impact and create a highly value-added technology to the precise mold manufacturing.
Authors: Hsin Chung Cheng, Chiung Fang Huang, Yi Lin, Yung Kang Shen
Abstract: This study indicates the micropattern of molded plastic film from a mold insert using ultrasonic micro embossing. A mold insert and plastic film are heated above the glass transition temperature of plastic, and the softened plastic is flowed into the micropattern of a mold insert by applying pressure via a conventional technique. A longitudinal ultrasonic wave is added to the ultrasonic micro embossing process. The longitudinal ultrasonic wave generated by an ultrasonic system at a frequency of 35 KHz, has amplitude of 20 μm and output power of 900 W. The micropatterns of the Ni mold insert are groove-shaped and they are 2-μm wide and 200-nm deep. The Polypropylene (PP) is chosen as the replication materials. This study identifies the replication properties of the plastic film using different process parameters (working pressure, ultrasonic pressure, packing pressure, working time, ultrasonic time and packing time). Results of this study demonstrate that ultrasonic time is the most important process parameter for ultrasonic micro embossing.
Authors: Chui Yu Chiu, Hsin Chuan Kuo, Yi Lin, Jeou Long Lee, Yung Kang Shen, Sheng Jie Kang
Abstract: The purpose of this research is to find the optimal design for biodegradable polymer microneedle patches. Based on the mechanical properties of different skin layers and the failure criterion of the material, this research designs a microneedle of four types and three sizes, then discusses the insertion force and the variation of stress during the process of PLA microneedle insertion into skin by numerical simulation. This research uses the dynamic finite element software ANSYS / LS-DYNA to simulate the processing for PLA microneedle inserts into skin. The master microneedle array was fabricated by the MEMS process. This research uses PDMS to fabricate the mould for microneedles. Finally, a biodegradable polymer polylactic acid (PLA) microneedle patch was fabricated using a PDMS mould micro hot embossing method.
Authors: Chui Yu Chiu, Yi Lin, Yu Chi Tseng, Yung Kang Shen
Abstract: Nanoporous anodic aluminum oxide (AAO) templates are fabricated using an anodization method. The mean diameters of nanoporous anodic aluminum oxide templates are 100 nm and 200 nm by various processing parameters of the anodization method. A molded plastic thin film nanostructure is fabricated by nanoimprinting using the AAO template as a mold. The surface properties of the molded plastic thin film are discussed using various nanoimprinting process parameters. Contact angles of the molded plastic thin film with the nanostructure exceed those without the nanostructure. The molded plastic thin films with a nanostructure and a hydrophobic surface are formed, and their contact angles exceed 90°.
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