Browsing by Author "Chen, Michael"

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An electrically tunable imaging system with separable focus and zoom functions using composite liquid crystal lenses
(2014-05-19)
Chen, Ming-Syuan
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Chen, Po-Ju
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Chen, Michael
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Lin, Yi-Hsin
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光電工程學系
We demonstrated an electrically tunable optical image system with separable focus function and zoom function based on three tunable focusing composite liquid crystal (LC) lenses. One LC lens in charge of the focus function helps to maintain the formed image at the same position and the other two LC lenses in charge of zoom function assist to continuously form an image at image sensor with tunable magnification of image size. The detail optical mechanism is investigated and the concept is demonstrated experimentally. The magnifications of the images can be switched continuously for the target in a range between 10 cm and 100 cm. The optical zoom ratio of this system maintains a constant similar to 6.5:1 independent of the object distance. This study provides not only a guideline to design the image system with an electrically optical zoom, but also provide an experimental process to show how to operate the tunable focusing lenses in such an image system. (C) 2014 Optical Society of America
An Electrically Tunable Polarizer for a Fiber System Based on a Polarization-Dependent Beam Size Derived From a Liquid Crystal Lens
(2014-06-01)
Chen, Michael
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Chen, Chyong-Hua
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Lai, Yinchieh
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Lu, Yan-qing
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Lin, Yi-Hsin
A broadband electrically tunable variable polarizer for fiber systems based on a liquid crystal lens is proposed and demonstrated. The polarization selectivity is based on a polarization-sensitive coupling efficiency to the fiber in the fiber system. For an incident ordinary ray, the output beam size remains the same as that of the incident beam, which results in low coupling efficiency. For an incident extraordinary ray (e-ray), the output beam size is close to the size of the fiber core, giving rise to high coupling efficiency because of the lens effect. Moreover, the output beam size of the e-ray can be electrically controlled, thus allowing the optical attenuation to be manipulated. In our experiments, the polarizationdependent loss from the visible to the near-infrared spectral region was approximately 12 dB. Such a broadband electrically variable polarizer may be applied to various designs for fiberoptic sensing devices and polarization-sensitive optical instruments.
An Electrically Tunable Polarizer for a Fiber System Based on a Polarization-Dependent Beam Size Derived From a Liquid Crystal Lens
(2014-06-01)
Chen, Michael
;
Chen, Chyong-Hua
;
Lai, Yinchieh
;
Lu, Yan-qing
;
Lin, Yi-Hsin
A broadband electrically tunable variable polarizer for fiber systems based on a liquid crystal lens is proposed and demonstrated. The polarization selectivity is based on a polarization-sensitive coupling efficiency to the fiber in the fiber system. For an incident ordinary ray, the output beam size remains the same as that of the incident beam, which results in low coupling efficiency. For an incident extraordinary ray (e-ray), the output beam size is close to the size of the fiber core, giving rise to high coupling efficiency because of the lens effect. Moreover, the output beam size of the e-ray can be electrically controlled, thus allowing the optical attenuation to be manipulated. In our experiments, the polarizationdependent loss from the visible to the near-infrared spectral region was approximately 12 dB. Such a broadband electrically variable polarizer may be applied to various designs for fiberoptic sensing devices and polarization-sensitive optical instruments.
An electrically-tunable liquid crystal lens coupler for the fiber communication systems
(2015-01-01)
Chen, Chyong-Hua
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Chen, Michael
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Lin, Yi-Hsin
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光電工程學系
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Department of Photonics
In this study, we demonstrated an electrically tunable lens coupler for both variable optical attenuation (VOA) and polarization selection. This coupler consists of a liquid crystal (LC) lens sandwiched between two GRIN lens. A GRIN lens is used to couple the light into the single mode fiber, and a LC lens is used to electrically manipulate the beam size of light. It is known that the lens power of a LC lens is tunable with high polarization sensitivity. Then, as the applied voltage on the LC lens is zero, the incident light is focused due to GRIN lens and coupled into the fiber. On the other hand, the beam size of the transformed e-ray becomes larger because the lens power of a LC lens for the e-ray decreases with the increase of the applied voltage. This results in the decrease of the coupling efficiency, and the optical power coupled into the fiber is smaller. This lens coupler for the e-ray functions as a VOA due to a continuous optical attenuation. On the contrary, the lens power of this LC lens for the o-ray does not vary because of optical anisotropy of the LC layer, and then the coupling efficiency for the o-ray remains high. For an arbitrary polarized incidence, this tunable lens coupler acts as a broadband polarizer for the fiber systems. The polarization dependent loss is larger than 30 dB and the switching time is around 1 second.
Development of a highly sensitive enzyme-linked immunosorbent assay (ELISA) through use of polyprotein G-expressing cell-based microplates
(2018-12-14)
Chen, Yi-Jou
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Chen, Michael
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Hsieh, Yuan-Chin
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Su, Yu-Cheng
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Wang, Chang-Hung
The sensitivity of traditional enzyme-linked immunosorbent assays (ELISAs) is limited by the low binding avidity and heterogeneous orientation of capture antibodies coated on polystyrene-based microplates. Here, we developed a highly sensitive ELISA strategy by fixing poly-protein G-expressing cells on microplates to improve the coating amount and displayed orientation of capture antibodies. One or eight repeated fragment crystallisable (Fc) binding domains of protein G are stably expressed on the surface of BALB/c 3T3 cells (termed 1pG cells or 8pG cells), which then act as highly antibody-trapping microparticles. The 8pG cells showed higher antibody-trapping ability than the 1pG cells did. The antibody-coating amount of the 8pG cell-based microplates was 1.5-23 times and 1.2-6.8 times higher than that of traditional polystyrene-based and commercial protein G-based microplates, respectively. The 8pG cell-based microplates were then applied to an anti-IFN-alpha sandwich ELISA and an anti-CTLA4 competitive ELISA, respectively, and dramatically enhanced their detection sensitivity. Importantly, direct coating unpurified capture antibody produced by mammalian cells did not impair the antigen-capturing function of 8pG cell-based microplates. The 8pG cell-based microplates exhibited a significant improvement in antibody-coating amount and preserved the homogeneous orientation of capture antibodies, making them a potential replacement for traditional microplates in various formats of ELISAs.
Development of an inflammatory tissue-selective chimeric TNF receptor
(2019-01-01)
Lee, Chia-Jung
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Wang, Chao-Ching
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Chen, Michael
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Chuang, Kuo-Hsiang
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Cheng, Tian-Lu
Background: Inhibiting TNF-alpha is an effective therapy for inflammatory diseases such as rheumatoid arthritis. However, systemic, nondiscriminatory neutralization of TNF-alpha is associated with considerable adverse effects. Methods: Here, we developed a trimeric chimeric TNF receptor by linking an N-terminal mouse Acrp30 trimerization domain and an MMP-2/9 substrate sequence to the mouse extracellular domain of TNF receptor 2 followed by a C-terminal mouse tetranectin coiled-coil domain (mouse Acrp-MMP-TNFR-Tn). Results: Here, we show that the Acrp30 trimerization domain inhibited the binding activity of TNFR, possibly by closing the binding site of the trimeric receptor. Cleavage of the substrate sequence by MMP-9, an enzyme highly expressed in inflammatory sites, restored the binding activity of the mouse TNF receptor. We also constructed a recombinant human chimeric TNF receptor (human Acrp-MMP-TNFR-Tn) in which an MMP-13 substrate sequence was used to link the human Acrp and the human TNF receptor 2. Human Acrp-MMP-TNFR-Tn showed reduced binding activity, and MMP-13 digestion recovered its binding activity with TNF-alpha. Conclusion: Acrp-masked chimeric TNF receptors may be able to be used for inflammatory tissue-selective neutralization of TNF-alpha to reduce the adverse effects associated with systemic neutralization of TNF-alpha.
Electrically assisting crystal growth of blue phase liquid crystals
(2014-05-01)
Chen, Michael
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Lin, Yi-Hsin
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Chen, Hung-Shan
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Chen, Hung-Yuan
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光電工程學系
We proposed an electrically assisting crystal growth of blue phase liquid crystals (BP-LCs) to generate uniform crystal orientation of BP-LCs. With an applied electric field, a phase transition from BP-LCs to focal conic state and homeotropic state occurs. As the electric field is removed, the crystal orientation of [220] quickly dominates the crystal growth process and other crystal orientations grow less at the same time. The BP-LCs with a single crystal orientation can be achieved with multiple cycles of the electrical treatment. We also provide a possible mechanism of crystal growth with electrical treatment which is applicable for both BP-LCs and PSBP-LCs. In addition, we conclude that the hysteresis effect is mainly affected by the domain size of PSBP-LCs rather than uniformity of crystal orientation. This study helps further understanding of the origin of hysteresis effect in PSBP-LCs which is important for development of many BP-LCs based photonic devices, such as micro lenses, displays, and lasers. (C) 2014 Optical Society of America
Hysteresis of Polymer Stabilized Blue Phase Liquid Crystals
(2012)
Chen, Hung-Shan
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Wu, Chun-Hung
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Chen, Michael
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Lin, Yi-Hsin
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光電工程學系
We demonstrate a hysteresis-free polymer-stabilized blue phase liquid crystals (PSBP-LCs) as well as hysteresis-free dye-doped polymer stabilized blue phase liquid crystals (DDPSBP-LCs) by means of enlarging the domain size and improving the uniformity of the crystal orientations of PSBP-LC and DDPSBP-LC. The mechanism based on the crystal growth is proposed. The hysteresis-free PSBP-LC (or DDPSBP-LC) is important in PSBP-LC-based photonic devices, such as displays, electro-optical switches, and electrically tunable focusing LC lenses.
Hysteresis-free polymer-stabilized blue phase liquid crystals using thermal recycles
(1970-01-01)
Chen, Hung-Shan
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Lin, Yi-Hsin
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Wu, Chun-Hung
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Chen, Michael
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Hsu, Hsu-Kuan
"We demonstrate a hysteresis-free polymer-stabilized blue phase liquid crystals (PSBP-LCs) using thermal recycles by means of enlarging the domain size of PSBP-LC and improving the uniformity of the crystal orientations of PSBP-LC. The crystal growth of PSBP-LCs bases on a competition between the heterogeneous nucleation and the homogeneous nucleation is also demonstrated and discussed. This study opens a new window for understanding the hysteresis of the PSBP-LC and assisting in designing many PSBP-LC-based photonic devices, such as displays, electro-optical switches, and electrically tunable focusing LC lenses. (C)2012 Optical Society of America"
Influence of alignment layers on crystal growth of polymer-stabilized blue phase liquid crystals
(2016-04-01)
Chen, Po-Ju
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Chen, Michael
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Ni, Shih-Ya
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Chen, Hung-Shan
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Lin, Yi-Hsin
The feature that devices based on blue phase liquid crystals (BPLCs) is free of alignment layers. However, the alignment layers could affect the morphologies of BPLC-devices as well as the electro-optical properties. In this paper, we investigate the influence of alignment layers to crystal growth of polymer-stabilized blue phase liquid crystals (PS-BPLCs). Without alignment layer, PS-BPLCs experiences both homogeneous nucleation and heterogeneous nucleation, and the morphology appears in random crystal orientations. On the contrary, when the surfaces coated with alignment layers, a heterogeneous nucleation dominates during the crystal growth process. We further proposed a possible mechanism for crystal growth under different surface condition. This study provides an alternative method to control crystal growth of PS-BPLCs, which is for facilitating many PS-BPLCs based photonic devices. (C) 2016 Optical Society of America
Sensitivity of PEGylated Interferon Detection by Anti-Polyethylene Glycol (PEG) Antibodies Depends on PEG Length
(2013-08-01)
Cheng, Ta-Chun
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Chuang, Kuo-Hsiang
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Chen, Michael
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Wang, Hsin-Ell
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Tzou, Shey-Cherng
Attachment of poly(ethylene glycol) to proteins can mask immune epitopes to increase serum half-life, reduce immunogenicity, and enhance in vivo biological efficacy. However, PEGylation mediated epitope-masking may also limit sensitivity and accuracy of traditional ELISA. We previously described an anti-PEG-based sandwich ELISA for universal assay of PEGylated molecules. Here, we compared the quantitative assessment of PEGylated interferons by anti-PEG and traditional anti-interferon sandwich ELISA. The detection limits for PEG-Intron (12k-PEG) and Pegasys (40k-PEG) were 1.9 and 0.03 ng/mL for anti-PEG ELISA compared to 0.18 and 0.42 ng/mL for traditional anti-interferon sandwich ELISA. These results indicate that the anti-PEG sandwich ELISA was insensitive to PEGylation mediated epitope-masking and the sensitivity increased in proportion to the length of PEG. By contrast, PEG-masking interfered with detection by traditional anti-interferon sandwich ELISA. Human and mouse serum did not affect the sensitivity of anti-PEG ELISA but impeded traditional anti-interferon sandwich ELISA. The anti-PEG sandwich ELISA was comparable to anti-interferon sandwich ELISA and radioassay of I-131-Pegasys in pharmacokinetic studies in mice. The anti-PEG sandwich ELISA provides a sensitive, accurate, and convenient quantitative measurement of PEGylated protein drugs.
Simulation Study on Polarization-Independent Microlens Arrays Utilizing Blue Phase Liquid Crystals with Spatially-Distributed Kerr Constants
(2014-12-01)
Chen, Hung-Shan
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Chen, Michael
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Chang, Chia-Ming
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Wang, Yu-Jen
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Lin, Yi-Hsin
Polarization independent liquid crystal (LC) microlens arrays based on controlling the spatial distribution of the Kerr constants of blue phase LC are simulated. Each sub-lens with a parabolic distribution of Kerr constants results in a parabolic phase profile when a homogeneous electric field is applied. We evaluate the phase distribution under different applied voltages, and the focusing properties of the microlens arrays are simulated. We also calculate polarization dependency of the microlenses arrays at oblique incidence of light. The impact of this study is to provide polarizer-free, electrically tunable focusing microlens arrays with simple electrode design based on the Kerr effect.