• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.400-401
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• 2006

광-바이오센서로 이용하기 위해 광섬유 형태의 마흐-젠더 간섭계와 측면 연마된 광섬유를 결합한 구조를 제안하였고, 이를 제작 및 특성 평가하였다. 마흐-젠더 간섭계 구성은 1310nm와 1550nm 파장에서 광 파워 분기비가 50:50인 $2{\times}2$ 광커플러 2개를 제작하여 구성하였으며, 센서부로는 측면 연마한 광섬유를 이용하였다. 제작된 광섬유 형태의 마흐-젠더 간섭계 센서의 센서부 표면에 다양한 굴절률 용액을 이용하여 광학적 특성을 평가하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.401-401
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• 2014

In this study, graphene, the most attractive material today, has been applied to the wavelength-modulated surface plasmon resonance (SPR) sensor. The optical fiber sensor technology is the most fascinating topic because of its several benefits. In addition to this, the SPR phenomenon enables the detection of biomaterials to be label-free, highly sensitive, and accurate. Therefore, the optical fiber SPR sensor has powerful advantages to detect biomaterials. Meanwhile, Graphene shows superior mechanical, electrical, and optical characteristics, so that it has tremendous potential to be applied to any applications. Especially, grapheme has tighter confinement plasmon and relatively long propagation distances, so that it can enhance the light-matter interactions (F. H. L. Koppens, et al., Nano Lett., 2011). Accordingly, we coated graphene on the optical fiber probe which we fabricated to compose the wavelength-modulated SPR sensor (Figure 1.). The graphene film was synthesized via thermal chemical vapor deposition (CVD) process. Synthesized graphene was transferred on the core exposed region of fiber optic by lift-off method. Detected analytes were biotinylated double cross-over DNA structure (DXB) and Streptavidin (SA) as the ligand-receptor binding model. The preliminary results showed the SPR signal shifts for the DXB and SA binding rather than the concentration change.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1516-1517
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• 2000

본 논문에서는 Porous Si(PSi)의 Photoluminescence(PL)특성을 이용한 UV detector를 이론적으로 고찰하곤 제작하였다. PSi의 PL에 의해 발생하는 빛의 피크 파장과 photodiode의 흡수영역을 최적화하여 UV detector의 효율을 극대화 시켰다. 제작된 PSi detector는 기존의 Si에 비해 반응 표면적을 증가시킬 수 있다는 장점이 있어 optical biosensor에 응용이 기대 된다.

• Korean Journal of Optics and Photonics
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• v.28 no.1
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• pp.9-15
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• 2017

We precisely measured and analyzed the dynamics of peptide-antibody interactions, using an ellipsometric biosensor based on a silicon substrate. To reduce the signal error due to the imperfect flatness of the substrate for extremely low concentrations of peptide, we fabricated the biosensor with a silicon substrate coated with Dextran SAM, instead of a glass prism coated with a thin metallic thin film. At an injection speed of $100{\mu}l/min$ of buffer liquid, we detected the dynamics of antibody-Dextran SAM or peptide-antibody fixed on biosensor, respectively. We detected the dynamics of antibody-Dextran SAM interactions down to a low concentration of 5 ng per liter, and we precisely measured the dynamics of association and dissociation of peptide and antibody down to 100 nM of peptide. We obtained the rate constants for association and dissociation from fitting the data by using deduced dynamical equation. As a result, we obtained an equilibrium constant for dissociation of 97 nM of peptide-antibody complex, which belongs to Class I.

• Applied Chemistry for Engineering
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• v.29 no.6
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• pp.645-651
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• 2018

Lung cancer has the highest death rate of any cancer diseases in Koreans. However, patients often feel difficult to recognize their disease before facing the terminal diagnosis due to the absence of any significant symptoms. Furthermore, the clear detection of an early cancer stage is usually obscure with existing diagnostic methods. For this reason, extensive research efforts have been made on introducing a wide range of biochemical diagnostic tools for the molecular level analysis of biological fluids for lung cancer diagnoses. A chip-based biosensor, one type of the analytical devices, can be a great potential for the diagnosis, which can be used without any further expensive analytical equipments nor skilled analysts. In this mini review, we highlight recent research trends on searching biomarker candidates and bio-chip sensors for lung cancer diagnosis in addition to discussing their future aspects.

• Bulletin of the Korean Chemical Society
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• v.28 no.11
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• pp.2083-2088
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• 2007

Biosensor based on rugate PSi interferometer for the detection of avidin has been described. Rugate PSi fabricated by applying a computer-generated pseudo-sinusoidal current waveform has been prepared for the application as a label-free biosensor based on porous silicon interferometer. The fabrication, optical characterization, and surface derivatization of a rugate PSi has been described. The method to fabricate biotinderivatized rugate PSi has been investigated. The surface and cross sectional morphology of rugate PSi are obtained with SEM. FT-IR spectroscopy is used to characterize the oxidation and functionalization reaction of rugate PSi sample. Binding of the avidin into the biotin-derivatized rugate PSi induces a change in refractive index. A red-shift of reflectivity by 18 nm in the reflectivity spectrum is observed, when the biotin-modified rugate PSi was exposed to a flow of avidin.

• KSBB Journal
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• v.10 no.1
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• pp.105-112
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• 1995

The fiber-optic biosensor using enzyme-immobilized Langmuir-Blodgett film is developed fort the measurement of ethanol. The enzyme, alcohol dehydrogenase, is immobilized at the molecular level on the arachidic acid monolayer using Langmuir-Blodgett film technique. Based on the ordered multisubstrate mechanism, the immobilized enzyme kinetics is investigated. The optical sensing system is proposed, and sensor signal is proportional to ethanol concentration and is related wish the number of enzyme layers. As the number of deposited LB film layer increases up to 20 1ayers, the high ethanol concentration of 45mM can be measured without the saturation of signal. Surface pressure-area isotherm is measured for the three-different charged-lipids. Arachidic acid is the most suitable for the adsorption of alcohol dehydrogenase based on electrostatic force.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.2
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• pp.163-168
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• 2023

In this paper, a novel platform for chemical sensing and biosensing is presented. The working principle is based on the coupling efficiency and interference properties of optical directional coupler (DC) and multimode interference coupler (MMIC). It has been realized using planar technology to allow integration on a silicon substrate. Firstly, the dispersion curves of DC and MMIC is described, and the design specification of an optimized slot optical waveguide to increase waveguide sensitivity is selected. Next, the sensor response to the refractive index change of sensing analyte is numerically simulated. The numerical results reveal that high effective index change per refractive index unit (RIU) change of analyte is obtained, and the sensitivity can be tuned using the DC and MMIC design technique.

• Analytical Science and Technology
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• v.27 no.3
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• pp.121-139
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• 2014

In this review, we will discuss aptamer technologies including in vitro selection, signal transduction mechanisms, and designing aptamers and aptazyme for label-free biosensors and catalysts. Dye-displacement, a typical label-less method, is described here which allows avoiding relatively complex labeling steps and extending this application to any aptamers without specific conformational changes, in a more simple, sensitive and cost effective way. We will also describe most recent and advanced technologies of signaling aptamer and aptazyme for the various analytical and clinical applications. Quantum dot biosensor (QDB) is explained in detail covering designing and adaptations for multiplexed protein detection. Application to aptamer array utilizing self-assembled signaling aptamer DNA tile and the novel methods that can directly select smart aptamer or aptazyme experimentally and computationally will also be finally discussed, respectively.

• Journal of Biosystems Engineering
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• v.30 no.2 s.109
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• pp.114-120
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• 2005

In this study, a biological reaction and measurement control system was developed to rapidly measure the insecticide imidacloprid residues in agricultural products. The biological reaction part of the system was designed to include micro-pumps and valves for fluid transport, and a polystyrene covet as a reaction chamber. The measurement control part of the system consisted of a photodiode with a light-emitting diode for optical density measurement, and a control microcomputer to implement assay. Signal output was read as the rate of change in optical density at 645 nm. The sensitivity of the system was 2.2 ng/mL ($IC_50$). The system could execute a measurement cycle in about 19 minutes. Research will be continued to develop an automatic sampler fur imidacloprid residues from agricultural products.