1,721,212 research outputs found
3-D diffuser lithography and its application to LCD/LED backlight unit and flexible front-light unit
No full textShape-controlled, high fill-factor microlens arrays fabricated by a 3D diffuser lithography and plastic replication method
No full textThis paper describes a simple and effective method to fabricate a plastic microlens array with controllable shape and high fill-factor, which utilizes the conventional lithography and plastic replication. The only difference from conventional lithography is the insertion of a diffuser that randomizes paths of the incident ultraviolet (UV) light to form lens-like 3D latent image in a thick positive photoresist. After replication of the developed concave microlens mold onto the polydimethylsiloxane ( PDMS), the focal length of the fabricated hemispherical microlens was observed to be 13-88 mum depending on the UV exposure dose. Two PDMS curing conditions were tested, where the elevated temperature of 85 degreesC resulted in smoother surface roughness of 2.6 nm in RMS value in the microlens mold. The proposed method can be extensively applied for microlens fabrication with other plastic materials due to its simplicity and versatility. (C) 2004 Optical Society of America
A 3-D planar microlens for an effective monolithic optical interconnection system
No full textA three-dimensional (3-D) planar microlens with curved sidewalls was fabricated by using the recently developed 3-D diffuser lithography and the polydimethylsiloxane (PDMS) replication method. The sidewall of the fabricated 3-D planar microlens had a radius of curvature of 140 mu m, and a well-defined focal spot with a width of 1.5 mu m and a height of 3 mu m was observed. An excellent single-mode fiber-to-fiber coupling efficiency of 71% was demonstrated by applying the developed 3-D planar microlens, which displayed more than two times the coupling ability compared to that of a conventional two-dimensional planar microlens with straight sidewalls. Finally, it was verified that the coupling efficiency was little affected by variation in the process conditions used for the photoresist mold fabrication
Self-assembled monolayer-assisted thin metal polishing for fabricating uniform 3D microstructures
No full textA self-assembled monolayer (SAM) was actively used to improve the reproducibility and yield of micromachining technology. A harsh metal mechanical polishing process was replaced with a metal wet etching process by using a hexadecanethiol (HDT) SAM as an etch-protect mask. The fundamental results of the experiment show the excellent ability of the HDT SAM in protecting the gold from the gold wet etchant and the wide process margin. The proposed process, which was used to fabricate a 3D suspended inductor, greatly improves the process yield. The proposed micromachining technology with a SAM is expected to have a variety of applications for the highly reproducible and uniform fabrication of MEMS
Parallel-Plate MEMS Variable Capacitor With Superior Linearity and Large Tuning Ratio Using a Levering Structure
No full textAn innovative and simple method is proposed to achieve ultralinear behavior in a capacitance-versus-voltage response and to obtain a large capacitance tuning ratio in a parallel-plate microelectromechanical systems (MEMS) variable capacitor by moving the plate to an increasing-gap direction. By adopting a levering structure, the common closing-gap motion of the electrostatic actuator was transformed into an increasing-gap movement in order to decrease the capacitance as the actuation voltage was increased. By balancing out the rate that the plate moves up as the actuation voltage increased and the rate that the capacitance decreases as the plate moves up, high linearity was achieved. The proposed MEMS variable capacitor, which was fabricated via metal surface micromachining, showed an excellent linearity factor (LF) of 99.5% in the C-V response, and a capacitance tuning ratio of 134% was achieved in the actual usage range (10-45 V) at a low frequency. When it was operated at 1 GHz, the proposed device demonstrated an LF of 99.5% and a capacitance tuning ratio of 125%
3D Integration of Microlenses to Realize a Low-Power and High-sensitivity Optical Detection System for a Disposable Lab-on-a-chip
No full text
Use of nanoporous columnar thin film in the wafer-level packaging of MEMS devices
No full textThis paper presents a new packaging technology that uses a nanoporous columnar thin film to seal microelectromechanical system (MEMS) devices at the wafer level. In the proposed packaging process, the processing temperature is 350 degrees C. The process is relatively inexpensive compared to wafer level packaging processes, because the wafer-bonding step is eliminated and the die size is shrunk. In the suggested approach, a sputtered columnar thin film at room temperature forms vertical nanopores as etch holes, and an air cavity is formed by the removal of a sacrificial layer through the nanopores in the columnar membrane. Subsequent hermetic vacuum packaging of the cavity is achieved by depositing thin films over the membrane under low pressure. The hermeticity of the packaging was verified by using an optical surface morphology microscope to measure the deflection change of the sealing membrane before and after breaking of the vacuum through an interconnected membrane. The long-term hermeticity was monitored by measuring the maximum central deflection of the PECVD sealing layer over a period of 170 days. The precise pressure (0.7 Torr) and short-term (30 days) pressure change inside the cavity were measured by encapsulated Ni Pirani gauges, representing packaged freestanding MEMS devices
마이크로셔터 블라인드 패널을 이용한 디스플레이 장치
No full textA display apparatus may be provided that includes: a transparent display panel; a blind panel which is disposed adjacent to the transparent display panel and includes a plurality of cells that are individually drivable; and a controller which changes an operation mode through an on/off of the transparent display panel and a selective drive of a cell included in the blind panel. As a result, the display apparatus according to the embodiment of the present invention is a transparent display apparatus using the OLED. The display apparatus is able to operate without the external environmental constraints and to operate in various modes including the display function
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