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The effects of the continuity of the surface pattern on wetting enhancement was investigated using micropillar and microhole arrays on hydrophilic and hydrophobic materials. Isolated micropillar arrays and continuous microhole arrays were prepared by a microscale imprinting technique using positive and negative Si molds fabricated by a conventional photolithography technique. The contact angles (CAs) and contact angle hysteresis (CAH) of the prepared surfaces were measured as a function of the surface parameter ξ, defined as the ratio of the top surface area of the microstructure to the surface area of the flat unit cell. It was found that the CAs of the micropillar array monotonically increased as the surface ratio decreased, regardless of the native wettability of the solid. However, an abnormal and consistent decrease of the CAs for the microhole array was observed when ξ0.5. To investigate the mechanism of this abnormality in wetting enhancement, the energy barriers for normal direction wetting, the so-called wetting transition from Cassi-Baxter (CB) wetting to Wenzel wetting, and lateral direction wetting, that is, spreading, were investigated with consideration of the trapped air in the microhole. The analysis unveiled that the hydrophobicity of the hydrophilic surfaces are attributable to the liquid-air interface pinning at the discontinuous edge of the pillar, which results in CB wetting. The abnormal decrease in the CAs of the microhole-patterned surfaces with ξ0.5 has been attributed to the relatively low energy barrier for spreading influenced by the continuity of the three-phase contact line. Additionally, trapped air in the microhole also plays a role in the spreading of water droplets by hindering the wetting transition from CB wetting to Wenzel wetting.

Carbon & Light Materials Application R&D Gropu, KITECH, Jeonju-city, Jellabuk-do 54853, Korea(Received March 14, 2016: Corrected March 21, 2016: Accepted March 25, 2016)초록: 본 연구에서는 소수성 구현을 위한 표면 거칠기가 접촉각과 접촉각 이력에 미치는 영향을 평가하였다. 초발수특성을 극대화하기 위해, 액적이 이동하기 위해 필요한 구름저항력을 제안하였으며, 이에 대한 평가를 통하여 표면에 형성한 패턴이 접촉각 이력 및 구름저항력에 큰 영향을 주는 것을 확인하였다. 초발수 특성이 요구되는 실제 응용을 위해서는 액적의 이동에 필요한 에너지를 최소화하기 위하여 접촉각을 극대화하고 동시에 접촉각 이력을 최소화하기 위한 표면 패턴 형상의 최적화가 요구됨을 확인하였다.Abstract: In this study, the effects of the contact angle (CA) and contact angle hyteresis (CAH) of planar and nano-patterned surfaces on rolling resistance of water droplet were studied. Based on the investigation on the CAH of waterdroplet on surfaces with various static wettability, it was found that the rolling resistance coefficient of water droplet ishighly influenced by the surface pattern as well as CAH. The observed results suggest that the optimal surface patternsshould be designed in order to minimize the rolling resistance of water droplet for the practical applications wheresuperhydrophocitiy is required.Keywords: Superhydrophobicity, Contact angle hysteresis, Rolling resistance, Rolling resistance coefficient

Division of Hematology/Oncology, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA(Received March 16, 2016: Corrected March 24, 2016: Accepted March 29, 2016)초록: 본 연구에서는 생체 영상 이미징을 위한 다채널 필터 모듈 개발 및 특성 평가 연구를 수행하였다. 필터 모듈은700 nm 및 800 nm 파장대의 근적외선 형광 이미징을 동시에 구현할 수 있도록 제작되었으며, 모듈의 특성 평가를 위해magnification, exposure, gain의 변수에 따른 signal to back ground ratio (SBR)을 통한 대조영상 평가를 진행하였다. 또한 생체 영상 분석을 위해 신장 및 간의 광학적 특성이 동일한 생체 모사 조직인 phantom을 제작하여 두께에 따른 필터모듈의 특성 및 광원의 주입량에 따른 특성 연구를 진행하였다. 제작된 필터 모듈은 magnification, exposure, gain의 변화에도 4이상의 SBR 차이를 보이며, kidney phantom 및 liver phantom의 경우 각각 50 mA, 60 mA의 광원 주입량에서4이상의 SBR 대조 영상을 확인하였다. Abstract: In this study, development of multichannel filter module and characteristic evaluation for bio imaging werestudied. The filter module was fabricated in order to realize near infrared fluorescence imaging of 700 nm and 800 nmwavelength ranges, and contrast imaging analysis for characteristic evaluation of the filter module was studied throughsignal to back ground ratio (SBR), controlled by parameters such as magnification, exposure, gain. Furthermore, phantoms,which are biomimetic tissue with equal optical properties of kidney and liver, were fabricated to study characteristics ofboth filter module depending on thickness and exposure amount of light source for bio imaging analysis. The fabricatedfilter module has more than 4 of SBR difference despite changes of magnification, exposure, gain, and in the case ofthe kidney phantom and the liver phantom, contrast imaging of more than 4 of SBR was confirmed on 50 mA, 60 mAexposure amount of light source respectively.Keywords: Medical image, Fluorescence filter system, Near-infrared fluorescence microscope, Phantom imaging

Department of Cogno-Mechatronics Engineering, Pusan National University, Geumjeong-gu, Busan 609-735, Korea(Received March 18, 2015: Corrected March 26, 2015: Accepted March 27, 2015)초록: 본 연구에서는 대면적 나노 금속 격자형 편광 필름 제작에서 증착 두께에 따른 광 특성 연구를 수행하였다. 나노 금속 격자형 편광필름은 PET(Polyethylene phthalate)기판 위에 알루미늄 선 격자 구조로 구성된다. 본 연구에서는 대면적 편광필름 제작을 위한 증착공정을 통한 금속 격자 형성을 목표로 하였으며, 금속 격자형 편광 필름 제작에 있어 최적의 투과율과 소광비를 가지는 금속 박막 형성 조건을 도출하였다. 최적화 공정에 의해 나노 금속 격자형 편광필름은140 nm 주기, 70 nm 선폭, 70 nm의 금속층 높이를 가지는 금속 격자 구조로 제작 되었다. 분석결과 600 nm 파장에서80% 이상의 최고 투과율 6및 10 이상의 소광비를 가지는 나노 금속 격자 편광필름의 높은 광 특성을 확인하였다. Abstract: In this study, we demonstrate the change of optical characteristic by thickness of metal deposition on nanometal grid polarizer film fabrication. Nano metal grid polarizer film consists of aluminium grid polarizer layer on PET(Polyethylene phthalate) substrate. We aim at metal grid layer formation for the large nano wire grid polarizer fabrication.we draw process conditions of the nano metal grid polarizer film fabrication to improve transmittance and extinction ratioand Nano wire grid polarizer film (NWGP) film is fabricated with 140 nm pitch, 70 nm width, and 70 nm depth of metalgrid on optimum design conditions. As a result, we get high optical properties of nano wire grid polarizer which is themaximum transmittance of 80% and the extinction ratio of 10

【Bioimaging has advanced the field of nanomedicine, drug delivery, and tissue engineering by directly visualizing the dynamic mechanism of diagnostic agents or therapeutic drugs in the body. In particular, wide-field, planar, near-infrared (NIR) fluorescence imaging has the potential to revolutionize human surgery by providing real-time image guidance to surgeons for target tissues to be resected and vital tissues to be preserved. In this review, we introduce the principles of NIR fluorescence imaging and analyze currently available NIR fluorescence imaging systems with special focus on optical source and packaging. We also introduce the evolution of the FLARE intraoperative imaging technology as an example for image-guided surgery.】

This study proposes a simple cost-effective method of optical interconnection with a view to minimizing and overcoming the excess loss caused by the alignment tolerance between optical waveguides in the integration/interface process in order to fabricate a large-area optical circuit layer. To that end, a large-area polymeric mold with a continuous channel structure was fabricated. The fabrication process consisted of fabricating the primary polymer mold by using the original master in the polymer replication process and involved the simple alignment of the replicated polymeric mold so that only some sections overlapped with the original master. The dimensions (i.e., width and thickness) of the cavity of the polymeric mold were identical to those of the original master. When the original master was inserted into the cavity of the polymeric mold after having separated the original master and the polymeric mold, the rib structures of the original master and the channel structures of the polymeric mold could be arranged in a passive alignment. A large-area polymeric mold with a continuous channel structure was fabricated by coating a polymeric solution onto the non-overlapping original master. For this study, a polymeric multimode optical waveguide with a length of 200 mm was fabricated using the original master with a length of 130 mm with 50 straight ribs. The excess loss of the proposed large-area multimode optical waveguide interconnection, compared with the original master-based optical waveguide, was 0 dB at 850 nm.

The roll to roll (RTR) imprint process is an integrated imprinting process where steps ranging from assignment of a function to a flexible rolled substrate to rewinding of the same substrate in a roll are performed. RTR imprint is a green, low-cost technology without limitations. In RTR imprint, it is important to manufacture the mold precisely and maintain uniform process condition. To this, process conditions have to include precision tension control, optimization of process parameters. We introduced RTR imprint to fabricate planar lightwave circuit (PLC) device for communication, by new schematic design and process optimization, we fabricated successfully optical device. The fabricated optical device showed the optical performance which was satisfied to meet international standard.

Optical devices are used extensively in the field of information network. Increasing demand for optical device, optical interconnection has been a important issue for commercialization. However many problems exist in the interconnection between optical device and optical fiber, and in the case of the multi-channel, problems of the optical alignment and optical array arise. For solving the alignment and array problem of optical device and the optical fiber, we fabricated fiber alignment and array by using imprint technology. Achieved higher precision of optical fiber alignment and array due to fabricating using imprint technology. The silicon stamp with different depth was fabricated using the conventional photolithography. Using the silicon stamp, a nickel stamp was fabricated by electroforming process. We conducted imprint process using the nickel stamp with different depth. The optical alignment and array by fabricating the patterns of optical device and fiber alignment and array using imprint process, and achieved higher precision of decreasing the dimensional error of the patterns by optimization of process. The fabricated optical interconnection of PLC device was measured 3.9 dB and 4.2 dB, lower than criteria specified by international standard.

In the nanoimprint lithography (NIL) stamp, a fluorinated self-assembled monolayer (SAM) is used as an antisticking layer. The uniformity and durability of the antisticking layer should be improved for achieving an effective fabrication of imprinted devices. In order to achieve these goals, we manufactured a vaporized SAM coating system with tilt and rotation functions, and we uniformly formed the antisticking layer on the stamp surface. The antisticking layer was with the 0.5 nm uniformity and the almost the same thickness of coating and re-coating. Moreover, to enhance durability, we conducted the pre-treatment before SAM coating and post-treatment after SAM coating – plasma cleaning, re-coating, deionized (DI) water deposition and annealing. The content of fluorine increased with re-coating, we could infer that the density of the antisticking layer increased via re-coating. To inspect the lifetime of the SAM-coated stamp, we measured the stamp surface contact angle in every five thermal NIL and identified that the durability of antisticking layer was dramatically improved.

We proposed the simple and attractive fabrication method of nickel stamp with improved sidewall roughness for polymeric optical devices. For this, the imprinted optical devices patterns under optimum imprinting conditions were annealed to improve the sidewall roughness generated by the DRIE process in the silicon stamp fabrication. The annealed sidewall roughness is reduced to 24.6 nm, nearly decreasing by 76% compared with the result before the annealing. Then, low cost and durable nickel stamp with improved sidewall roughness was fabricated by the annealed polymeric patterns being used as original master for electroforming process. And, we verified the superiority of the improved nickel stamp by comparing the optical propagation losses for optical waveguides to be fabricated, respectively, using the nickel stamp and original silicon stamp. The optical waveguides fabricated by the imprint lithography using the improved nickel stamp was demonstrated that their optical losses were reduced as 0.21 dB/cm, which was less than the propagation loss for polymeric waveguides using the conventional original silicon stamp. This result could show the effectiveness of the fabricated nickel stamp with improved sidewall roughness. Furthermore, we were able to successfully fabricate a polymeric 1 × 8 beam splitter device using the improved nickel stamp. And, the insertion loss for eight channels obtained to be from 10.02 dB to 10.91 dB.

Although imprint technology has made considerable progress in recent times, there are certain limitations on its use because of several problems. One of these is the reliability caused by the dimensional change of the imprinted structure. In particular, a hot-embossed structure is inherently involved in residual stress due to the temperature and pressure cycle during the fabrication process. A structure with residual stress undergoes stress relaxation, which leads to dimensional change. Therefore, we have conducted research on its dimensional stability by using an annealing process. To evaluate the reliability of an imprinted structure, it is necessary to measure changes in the mechanical properties, such as elastic modulus, micro-hardness, residual stress, and dimensional change. Through these measurements, we propose a way of controlling the level of residual stress. Before annealing, the dimension of an imprinted structure changes by 0.9 μm during one month. However, after annealing, a dimensional change of 0.3 μm was observed over the same period.

With increasing the interest in environment-friendly vehicles such as electric vehicle, hybrid electric vehicle and fuel cell electric vehicles, variable speed driving systems are continuously researched and developed. The demand for the main driving motor of high efficiency, high power and high speed is highly increasing. Recently, as a motor satisfying this demand, the interior permanent magnet synchronous motor which adopted high energy density magnet is being mainly used. In this paper, electromagnetic analysis and optimal dimension design for the electric driving motor using the finite element method and MotorPro™ software are performed. Through the experiments, the performance of the developed motor is proved.

We propose an integrated structure that combines chip and fiber array blocks for optical interconnection with a polymeric planar lightwave circuit (PLC) device using the roll-to-roll imprint process. The fiber array blocks and PLC chip of the integrated structure are fabricated on the same substrate, and the alignments in the three spatial directions were established with the insertion of an optical fiber. The characteristics of the integrated structure were evaluated by fabricating a 1×2 optical splitter device. The structure had an insertion loss of 3.9 dB, and the optical uniformity of the channel was 0.1 dB, indicating that the same performance for an active alignment can be expected.

Here, we present a new double-side patterned sapphire sub- strate methodology that improves the efficiency of gallium nitride-light emitting diodes (GaN-LEDs). The light extraction efficiency of GaN- based LEDs was analyzed through the use of a ray-tracing simulation. The extraction efficiency was simulated using patterned sapphire sub- strate LEDs with a variety of shapes, depths, sizes, and spacing. Through the optimal patterning of the various factors, high extraction effi- ciency was realized and subsequently improved upon. The thermal LED characteristics were analyzed through the use of the COMSOL general heat transfer module. The LEDs patterned on the sapphire substrate were fabricated using nano imprint lithography. We found that the output power of the double-side patterned LED was 52% greater than that of a flat LED. The thermal resistance of the double side patterned LED was 9.5 K∕W less than that found for the flat LED. © The Authors. Published by