With the wide application of portable wearable devices, a variety of electronic energy storage devices, including microsupercapacitors (MSCs), have attracted wide attention. Laser-induced graphene (LIG) is widely used as electrode material for MSCs because of its large porosity and specific surface area. To further improve the performance of MSCs, it is an effective way to increase the specific surface area and the number of internal active sites of laser-induced graphene electrode materials. In this paper, N-doped polyimide/polyvinyl alcohol (PVA) as precursor was used to achieve in situ doping of nitrogen atoms in laser-induced graphene by laser irradiation. Through the addition of N atoms, nitrogen-doped laser-induced threedimensional porous graphene (N-LIG) exhibits large specific surface area, many active sites, and good wettability all of which are favorable conditions for enhancing the capacitive properties of laser-induced graphene. After assembly with PVA/H2SO4 as gel electrolyte, the high surface capacitance of the MSC device with N-LIG as electrode material is 16.57 mF cm− 2 at the scanning rate of 5 mV s− 1, which is much higher than the 2.89 mF cm− 2 of the MSC device with LIG as electrode material. In addition, MSC devices with N-LIG as electrode materials have shown excellent cyclic stability and flexibility in practical tests, so they have a high application prospect in the field of flexible wearable microelectronics.

Laser induced surface activation (LISA) technology requires refined selection of process variables to fabricate conductive microcircuits on a general polymer material. Among the process variables, laser mode is one of the crucial factors to make a reliable conductor pattern. Here we compare the continuous wave (CW) laser mode with the pulse wave (PW) laser mode through determination of the surface roughness and circuit accuracy. In the CW laser mode, the surface roughness is pronounced during the implementation of the conductive circuit, which results in uneven plating. In the PW laser mode, the surface is relatively smooth and uniform, and the formed conductive circuit layer has few defects with excellent adhesion to the polymer material. As a result of a change of laser mode from CW to PW, the value of Ra of the polymer material decreases from 0.6 m to 0.2 m; the value of Ra after the plating process decreases from 0.8 m to 0.4 m, and a tight bonding force between the polymer source material and the conductive copper plating layer is achieved. In conclusion, this study shows that the PW laser process yields an excellent conductive circuit on a polymeric material.

다공성 분리막은 입자성 물질을 제거하는데 산업적으로 다양하게 응용되고 있다. 기존 다공성 분리막 제작 방법 과 다르게, 용액퍼짐 상분리법은 매우 간단하게 기공을 형성할 수 있다. 먼저 지지층으로 메쉬 위에 물을 적신 후, 물과 혼합 되지 않은 용매에 폴리설폰 용액을 흘려준다. 이때 물과 혼합되지 않은 용매는 쉽게 기화되어 폴리설폰은 얇은 막으로 만들어지게 된다. 기공을 형성하기 위해 폴리설폰 용액에 물과 혼합할 수 있는 물질을 넣게 되면, 넣어주는 농도 비율에 따라 기공크기를 조절할 수 있게 된다. 막의 두께는 쉽게 용액의 농도로 조절이 된다. 다공성 분리막은 메쉬의 형성을 그대로 유지하고 있어 3차원 구조체를 형성하는데 매우 유용하다. 본 연구에서 제시된 용액 퍼짐 상분리법은 매우 낮은 생산단가와 쉬운 공정조절에 의해 기존 분리막에 비해 높은 가격경쟁력을 가질 수 있는 특징을 보이고 있다.

Surface plasmon resonance is the resonant oscillation of conduction electrons at the interface between negative and positive permittivity material stimulated by incident light. In particular, when light transmits through the metallic microhole structures, it shows an increased intensity of light. Thus, it is used to increase the efficiency of devices such as LEDs, solar cells, and sensors. There are various methods to make micro-hole structures. In this experiment, micro holes are formed using a wet chemical etching method, which is inexpensive and can be mass processed. The shape of the holes depends on crystal facets, temperature, the concentration of the etchant solution, and etching time. We select a GaAs(100) single crystal wafer in this experiment and satisfactory results are obtained under the ratio of etchant solution with H2SO4:H2O2:H2O = 1:5:5. The morphology of micro holes according to the temperature and time is observed using field emission - scanning electron microscopy (FE-SEM). The etching mechanism at the corners and sidewalls is explained through the configuration of atoms.

An optimum route to fabricate a hybrid-structured W powder composed of nano and micro size powders was investigated. The mixture of nano and micro W powders was prepared by a ball milling and hydrogen reduction process for WO3 and W powders. Microstructural observation for the ball-milled powder mixtures revealed that the nano-sized WO3 particles were homogeneously distributed on the surface of large W powders. The reduction behavior of WO3 powder was analyzed by a temperature programmed reduction method with different heating rates in Ar-10% H2 atmosphere. The activation energies for the reduction of WO3, estimated by the slope of the Kissinger plot from the amount of reaction peak shift with heating rates, were measured as 117.4 kJ/mol and 94.6 kJ/mol depending on reduction steps from WO3 to WO2 and from WO2 to W, respectively. SEM and XRD analysis for the hydrogen-reduced powder mixture showed that the nano-sized W particles were well distributed on the surface of the micro-sized W powders.

Magnetostrictive actuator is fabricated with powder nano bonding method instead of sputtering method. Fabrication process and experimental measurement method for magneto-mechanical characteristics is proposed. For the design of highly flexible magnetostrictive actuator, TbDyFe nano powder bonding with Teflon substrate is adopted. The fabrication process for Teflon substrate and nano powder bonding is suggested and magnetostrictive behaviors are investigated. Variable magnetic field is applied to measure the magnetostrictive characteristics and magnetostriction is measured with different waves and different magnitude of magnetic field.

Recently, products that a have 3-dimensional(3D) micro structure have been in wide use. To fabricate these 3D micro structures, several methods, such as stereo lithography, reflow process, and diffuser lithography, have been used. However, these methods are either very complicated, have limitations in terms of patterns dimensions or need expensive components. To overcome these limitations, we fabricated various 3D micro structures in one step using a pair of diffusers that diffract the incident beam of UV light at wide angles. In the experiment, we used positive photoresist to coat the Si substrate. A pair of diffusers(ground glass diffuser, opal glass diffuser) with Gaussian and Lambertian scattering was placed above the photomask in the passage of UV light in the photolithography equipment. The incident rays of UV light diffracted twice at wider angles while passing through the diffusers. After exposure, the photoresist was developed fabricating the desired 3D micro structure. These micro structures were analyzed using FE-SEM and 3D-profiler data. As a result, this dual diffuser lithography(DDL) technique enabled us to fabricate various microstructures with different dimensions by just changing the combination of diffusers, making this technology an efficient alternative to other complex techniques.

This study is carried out to develop the new process for the fabrication of ultra-fine electrodes on the flexible substrates using superhydrophobic effect. A facile method was developed to form the ultra-fine trenches on the flexible substrates treated by plasma etching and to print the fine metal electrodes using conductive nano-ink. Various plasma etching conditions were investigated for the hydrophobic surface treatment of flexible polyimide (PI) films. The micro-trench on the hydrophobic PI film fabricated under optimized conditions was obtained by mechanical scratching, which gave the hydrophilic property only to the trench area. Finally, the patterning by selective deposition of ink materials was performed using the conductive silver nano-ink. The interface between the conductive nanoparticles and the flexible substrates were characterized by scanning electron microscope. The increase of the sintering temperature and metal concentration of ink caused the reduction of electrical resistance. The sintering temperature lower than resulted in good interfacial bonding between Ag electrode and PI film substrate.

본 연구는 마이크로 스케일의 내부 구조를 갖는 3차원 인공지지체를 제작하기 위하여 개발된 제조 시스템의 성능 분석을 위해 x-y축 정밀 스테이지 시스템으로 조립되었을 때의 해상도 및 정확도를 측정 하였으며, z축 정밀 스테이지를 분리하여 다양한 물리적 오차를 제거하였다. 기존의 x-y-z축 정밀 스테이 지 시스템을 x-y축으로 분리하고 각 축의 이동거리를 4종류(±0.25μm, ±0.5μm, ±25μm, ±50μm)로 설정하여 각 위치마다의 변위를 레이저 측정기를 이용하여 기록하였다. 가장 작은 이동거리(±0.25μm)에서의 진동이 상대적으로 가장 크게 나타났으며, y축 스테이지 위에 x축 스테이지를 조립하였기 때문에 x축 스테이지 자중에 의한 모멘텀으로 인하여 y축 스테이지 구동변위 값이 크게 나타났다. 하지만 z축 스테이지는 기존 시스템과 달리 별로도 분리하여 구동 오차를 줄였으며, 일체화된 광학시스템을 적용하여 광학오차를 감 소시켰다. 따라서 새로운 시스템에서는 500μW, 140mm/min의 가공조건에서도 마이크로 스케일의 3차원 인 공지지체 형상의 구조물을 성공적으로 제작할 수 있었다.

To fabricate a precise micro metal mold, the electrochemical etching process has been researched. We investigated the electrochemical etching process numerically and experimentally to determine the etching tendency of the process, focusing on the current density, which is a major parameter of the process. The finite element method, a kind of numerical analysis, was used to determine the current density distribution on the workpiece. Stainless steel(SS304) substrate with various sized square and circular array patterns as an anode and copper(Cu) plate as a cathode were used for the electrochemical experiments. A mixture of H2SO4, H3PO4, and DIW was used as an electrolyte. In this paper, comparison of the results from the experiment and the numerical simulation is presented, including the current density distribution and line profile from the simulation, and the etching profile and surface morphology from the experiment. Etching profile and surface morphology were characterized using a 3D-profiler and FE-SEM measurement. From a comparison of the data, it was confirmed that the current density distribution and the line profile of the simulation were similar to the surface morphology and the etching profile of the experiment, respectively. The current density is more concentrated at the vertex of the square pattern and circumference of the circular pattern. And, the depth of the etched area is proportional to the current density.

Novel polymer mold process for fabrication of microcomponents using metal nanopowders was developed and experimentally optimized. Polymer mold for forming green components was produced by using a hard master mold and polydimethylsiloxane (PDMS). In the preparation of metallic powder premix for the green components without any defect, 90 wt.% 17-4PH statinless steel nanopowders and 10 wt.% organic binder were mixed by a ball milling process. The green components with very clear gear shape were formed by filling the powder premix into the PDMS soft mold in surrounding at about . Cold isostatic pressing (CIP) was very potent process to decrease a porosity in the sintered microcomponent. The microgear fabricated by the improved process showed a good dimension tolerance of about 1.2%.

We newly designed and manufactured a new arranging system for a three-dimensional artificial crystal of monosized micro particles. In this system, a robotic micro-manipulator accurately locates the spherical particle onto the lattice point, and subsequently fiber lasers micro-weld the contact points between the neighboring particles. Actually, one- and two-dimensional arrays were constructed using monosized tin particles with the diameter of 400 m. Moreover, due to optimization of the process parameters, we successfully constructed the artificial crystals of simple cubic and diamond structures. In particular, the diamond structure which can represent a large photonic band gap is expected to progress toward a practical photonic crystal device.

Manufacturing technologies of micro parts were studied in nano grained Al-1.5mass%Mg alloy. During compressive test at 300 , the Al alloy showed stain softening ℃ phenomenon by grain boundary sliding regardless of strain rate. Micro spur gear with ten teeth (height of 200 μm and pitch of 250 μm) was fabricated with sound shape by micro forging. During micro forging, increase of applied stress induced by friction between material and die surface was effectively compensated by decrease of stress by strain softening behavior and as a result, flow stress increased only about 50 MPa more than that in compressive test.

New powder compaction process, in which a Bingham semi-solid/fluid mold is utilized, is developed to fabricate micro parts. In the present process, a powder material is filled as slurry in a solid wax mold, dried and compressed. The wax is heated during compaction and becomes semi-solid state, which can acts as a pressurized medium for isostatic compaction. Since the compacted micro parts are very fragile, the mold's temperature is controlled to higher than its melting point during unloading, to avoid breakage of the compacts. To demonstrate effectiveness of this process, some micro compacts of alumina are shown as examples.

사진식각 공정으로 종횡비가 매우 큰 유리 미세구조물을 제작하였다. 미세구조물의 제작에는 압축응력에 강하고 전기적 절연체인 감광성 유리를 사용하였다. 감광성 유리는 석영기판 위에 크롬이 패턴된 마스크를 사용하여 파장이 312nm인 자외선에 노광되었다. 500˚C 이상의 열처리공정을 거친 후 초음파 분위기에서 10%의 불산용액으로 식각함으로써 유리 미세구조물을 제작하였다. 미세구조물의 최종 형상은 감광성 유리의 두께, 마스크 패턴, 자외선 노광조건 및 식각조건에 크게 의존하였으며, 종횡비가 30이상인 스트라이프 구조의 유리 미세구조물을 제작할 수 있었다.