Jeou Long Lee

Microfluidic chip fabrication for silicon mold insert by micro hot embossing

This study uses the microfluidic chip as an example to discuss its properties using silicon mold insert by micro hot embossing molding. This study uses the lithography technology to fabricate the silicon mold insert. In this study, the authors use the Taguchi method (L9 table) to discuss the different processing parameters for the properties of molded microfluidic chip. The results show that the most important parameter is the embossing temperature for replication properties of molded microfluidic chip and the de-molding temperature is most important parameter for surface roughness for molded microfluidic chip.

A Study of the Microstructure and Properties of Electroformed Ni-P Model Insert

In this study, a Ni-P alloy electroforming nanostructure material with low surface roughness and low internal stress was developed by using a pulse current. Square-wave cathodic current modulation was employed to electrodeposit ultrafine-grained Ni-P films from an additivefree Sulfamate nickel bath. The effect of various factors, such as peak current density, duty cycle and pulse frequency on the roughness and internal stress were investigated. Pulse current significantly influences the microstructure of Ni-P alloys. The internal stress and roughness of Ni-P alloys increased as peak current density increased, but the internal stress of Ni-P alloys decreased as duty cycle decreased.

Optimal Design of Microneedles Inserts into Skin by Numerical Simulation

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.

Surface Modification of Plastic Thin Film Using Anodic Aluminum Oxide Template for Nano Imprint

Nano-porous anodic alumina oxide (AAO) templates are fabricated by anodizing method. The average diameter of nano-porous anodic alumina is 200 nm. The molded plastic thin film (Polycarbonate, PC) with nano-structure is fabricated by AAO as mold insert for nanoimprint. This research discusses the surface property of molded plastic thin film for different processing parameters (embossing temperature, embossing pressure, embossing time, de-molding temperature) on nanoimprint. The original contact angle of PC material without nano-structrue is about 78.2°. The contact angle of molded PC with nano-structrue is about 115.5°. The contact angle of molded plastic film (PC) with nano-structure is larger than that without nano-structure. The hydrophilic property of PC material has changed to hydrophobic property. A significant advantage of the fabrication process employed in this work is that it can create the good surface modification of plastic thin film.

Fabrication and detection for the skeletons of micro aerial vehicle using precision injection molding

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.

Fabrication and analysis of microfluidic mold insert by micro electrical discharge machining

This study develops an improved method for generating aluminum mold inserts used in the replication of polymer-based microfluidic chip. Since molding masters that are suitable for microfluidic chip replication must have features whose dimensions are of the order of tens to hundreds of microns, micro electrical discharge machining is employed herein to fabricate an aluminum mold insert of a microfluidic chip. The width and depth of the aluminum mold insert for the microfluidic chip are 61.50 µm and 49.61 µm, respectively. The surface roughness values of the microchannel and the sample reservoir in aluminum mold insert for the microfluidic chip are 59.92 nm and 34.34 nm, respectively. PMMA material is adopted as the molded microfluidic chip that is produced by micro-hot embossing molding. The PMMA material can replicate the microchannel and sample reservoir very well when the aluminum mold insert is used in micro-hot embossing molding. The results indicate that the most important parameter in the replication of molded microfluidic chip is the embossing pressure, which is also the most important parameter in determining the surface roughness of the molded microfluidic chip.

Morphological evolution of nanostructured surface using anodic aluminum template

Nanoporous anodic aluminum oxide (AAO) templates are fabricated using an anodization method. The mean diameter of the nanoporous anodic aluminum oxide templates is 100 nm. A molded plastic thin film with nano-structure is fabricated using AAO template as a mold insert by nanoimprint. The surface properties of the molded plastic thin film obtained using various processing parameters in nanoimprint are discussed. The contact angle of the molded polycarbonate (PC) thin film with the nano-structure exceeds that without the nano-structure. The molded PC thin film (with nano-structure) with a hydrophobic surface is formed, and has a water contact angle of 128.5°. The use of anodic aluminum oxide to prepare a mold insert for nanoimprint supports the formation of a nano-structure in the molded PC thin film, and effectively increases its reflectance.

Warpage Measurement of a Micro Electrical Fan on Micro-Injection Molding

This study characterizes warpage of a micro-injection molded micro electrical fan using the Michelson interference method. This study conducts experiments to analyze different polymers-polypropylene (PP), polyamide (PA), acrylonitrile-butadiene styrene (ABS), ABS+ polycarbonate (PC), and polyoxymethylene (POM)-process parameters, such as mold temperature, injection temperature, injection pressure, injection time, packing time, and packing pressure, for a micro electrical fan. To obtain the optimum result (minimum warpage), this study assesses the effect (warpage) of each material on micro-injection molding. PA plastic is the very suitable material for micro electrical fan with Michelson interference analysis on micro-injection molding.

Rapid forming of hydroxyapatite-silica ceramics

This paper proposes a solid freefrom fabrication (SFF) technology for fabricating hydroxyapatite(HA)-silica ceramics, which can generate porous three-dimensional physical objects. The HA powder and the silica are mixed with water into slurries form as raw materials. The slurries are paved by a scraper to from a thin layer which is selective scanned by a laser beam according to the cross-section of a 3D model. The HA particles are embeded in the sintered silica matrix to form green parts via a suitable range of process parameters. The benefits of this process are: bio-ceramic parts can be built by lower laser energy and faster fabricating speed. Following a subsequence heat treatment process has been developed to optimize the crystallization process and to increase the strength of the sintered parts. The parts were analyzed by an Atomic Force Microscope (AFM) to determine the surface roughness. The results obtained indicate that the proposed process was possible to generate multilayer, overhanging, and porous structure with brittle property but sufficient integrity for handling prior to post-processing. It was possible to produce the porous structure from the proposed hydroxyapatite-silica ceramics, which had a greater potential for possible bone scaffolds fabrication.

Fabrication Inner Channel Ceramics Using Layer Additive Method

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.