표면 플라즈몬 현미경을 이용한 자기조립 단분자막의 이미징

표현봉,신용범,윤현철,양해식,김윤태 한국광학회 2003 한국광학회지 Vol.14 No.1

이차원 표면 플라즈몬의 공명 흡수와 포토 마스크를 이용하여 11-MUA(11-Mercaptoundecanoic acid)와 11-MUOH(11-Mercaptoundecanol) 둥으로 이루어진 자기조립 단분자막(Self-Assembled Monolayer; SAM)의 다채널 영상을 얻었다. 통상의 Photoresist를 이용한 리토그래피 대신에 Thiol bonding의 광산화를 이용하여 패터닝 과정을 줄이고, 백색광 및 대역통과 필터(λ$_{0}$=633nm)를 이용하여 입사광으로써 레이저를 사용할 때 나타나는 간섭무늬를 줄였다. 이로부터 나타나는 이차원 영상의 명암을 정량적으로 보정하면 수 나노미터(nm) 두께의 변화를 측정할 수 있다. 또한 표면 플라즈몬 공명법은 국소화된 근접장 (소산장)을 이용하는 방법으로서, 통상 많이 이용되는 형광법 등에서 나타나는 광탈색(Photobleaching)이나 소광(Quenching) 현상이 없이 시료의 처리가 간단하고, 영상 신호의 시간에 따른 변화가 극히 적으며, 실시간으로 신호의 변화를 측정할 수 있다는 장점이 있다. Multi-channel images of 11-MUA(11-Mercaptoundecanoic acid) and 11-MUOH(11-Mercaptoundecanol) self-assembled monolayers were obtained by using two-dimensional surface plasmon resonance (SPR) absorption. The patterning process was simplified by exploiting direct photo-oxidation of thiol bonding (photolysis) instead of conventional photolithography. Sharper images were resolved by using a white light source in combination with a narrow bandpass filter in the visible region, minimizing the diffraction patterns on the images. The line profile calibration of the image contrast caused by different resonance conditions at each point on the sensor surface (at a fixed incident angle) enables us to discriminate the monolayer thickness in nanometer scale. Furthermore, there is no signal degradation such as photo bleaching or quenching, which are common in the detection methods based on fluorescence.

e-Health 구현을 위한 바이오센서

표현봉 한국차세대컴퓨팅학회 2005 한국차세대컴퓨팅학회 논문지 Vol.1 No.1

Plasmonic Biosensor

표현봉,정문연,박선희 한국바이오칩학회 2007 BioChip Journal Vol.1 No.4

Issues on optical and physical characteristics of plasmonic biosensor were described. Starting from physical principles of surface plasmons, resonant coupling, and dispersion, we then discussed more practical and essentially important aspects on dielectric functions, penetration depth, and functional differences in SPR imaging systems. Scaling procedure from experimentally obtained SPR curve to incident angle was also discussed. Also, physical background of plasmon-resonant, extinction-, scattering- and near-field cross-section of metallic nanoparticles was briefly explained, based on Mie scattering. Extinction spectra were calculated for various sizes of gold and silver anoparticles and compared with experimentally observed extinction spectra for colloidal gold.

Fabrication of Nonbiofouling Surface and Its Application to Surface Plasmon Field-Enhanced Fluorescence Spectroscopy

김은경,이봉수,표현봉,송현우,김영필,최인성,김학성 한국바이오칩학회 2008 BioChip Journal Vol.2 No.2

Reducing the non-specific binding of proteins on a chip surface is essential for the development of biosensors with high sensitivity and specificity. We fabricated poly(oligo(ethylene glycol) methacrylate) (pOEGMA) films with various thicknesses as a nonbiofouling surface for surface plasmon field-enhanced fluorescence spectroscopy (SPFS). To accomplish a sensitive SPF signal, the thickness of the pOEGMA films was controlled by surface-initiated atom transfer radical polymerization (SI-ATRP) on gold-coated glass (Au/Glass) and gold-coated Si (Au/Si) substrates. When fluorophores immobilized on the pOEGMA films were directly excited without a plasmon effect, the fluorescence intensity displayed a linear dependency on the tested thickness of the pOEGMA films on both Au/Si (9-60 nm) and Au/Glass (8-56 nm). As a result, the surface plasmon fieldinduced fluorescence intensity on Au/Glass enabled thickness-dependent sensitivity. The SPF signal on 50-nm-thick pOEGMA films was estimated to be 100-fold stronger than that on 13-nm-thick pOEGMA films. Since the SPFS on pOEGMA film can allow an easy conjugation of biomolecules and provide a high resistance to biofouling events, our fabricated system has a great potential as a platform for biosensors with high sensitivity. Reducing the non-specific binding of proteins on a chip surface is essential for the development of biosensors with high sensitivity and specificity. We fabricated poly(oligo(ethylene glycol) methacrylate) (pOEGMA) films with various thicknesses as a nonbiofouling surface for surface plasmon field-enhanced fluorescence spectroscopy (SPFS). To accomplish a sensitive SPF signal, the thickness of the pOEGMA films was controlled by surface-initiated atom transfer radical polymerization (SI-ATRP) on gold-coated glass (Au/Glass) and gold-coated Si (Au/Si) substrates. When fluorophores immobilized on the pOEGMA films were directly excited without a plasmon effect, the fluorescence intensity displayed a linear dependency on the tested thickness of the pOEGMA films on both Au/Si (9-60 nm) and Au/Glass (8-56 nm). As a result, the surface plasmon fieldinduced fluorescence intensity on Au/Glass enabled thickness-dependent sensitivity. The SPF signal on 50-nm-thick pOEGMA films was estimated to be 100-fold stronger than that on 13-nm-thick pOEGMA films. Since the SPFS on pOEGMA film can allow an easy conjugation of biomolecules and provide a high resistance to biofouling events, our fabricated system has a great potential as a platform for biosensors with high sensitivity.

SiOx / (FePt, CoPt) / SiOx / Al 다층 박막의 극 Kerr 효과 수치해석

서동우,박용우,류호준,손영준,표현봉,백문철 한국자기학회 2003 한국자기학회 학술연구발표회 논문개요집 Vol.13 No.1

Miniaturized Electronic Nose System Based on Personal Digital Assistant

Yong Shin Kim,양윤석,표현봉,최창억,Seung-Chul Ha 한국전자통신연구원 2005 ETRI Journal Vol.27 No.5

A small electronic nose (E-Nose) system has been developed using an 8-channel vapor detection array and personal digital assistant (PDA). The sensor array chip, integrated on a single microheater- embedded polyimide substrate, was made of carbon black-polymer composites with different kinds of polymers and plasticizers. We have successfully classified various volatile organic compounds such as methanol, ethanol, i-propanol, benzene, toluene, n-hexane, n-heptane, and c-hexane with the aid of the sensor array chip, and have evaluated the resolution factors among them, quantitatively. To achieve a PDAbased E-Nose system, we have also elaborated small sensor-interrogating circuits, simple vapor delivery components, and data acquisition and processing programs. As preliminary results show, the miniaturized E-Nose system has demonstrated the identification of essential oils extracted from mint, lavender, and eucalyptus plants.

지능형 후각센서

이대식,안창근,김봉규,표현봉,김진태,허철,김승환,Lee, D.S.,Ahn, C.G.,Kim, B.K.,Pyo, H.B.,Kim, J.T.,Huh, C.,Kim, S.H. 한국전자통신연구원 2019 전자통신동향분석 Vol.34 No.4

With advances in olfactory sensor technologies, the number of reports on various intelligent applications using multiple sensors (sensor arrays) are continuously increasing for fields such as medicine, environment, security, etc. For intelligent and point-of-care applications, it is not only important for the sensor technology to perform chemical or physical measurements rapidly and accurately, but it is also important for artificial intelligence technology to recognize and quantify specific chemicals or diagnose diseases such as lung cancer and diabetes. In particular, great advances in pattern recognition technologies, including deep learning algorithms, as well as sensor array technologies, are expected to enhance the potential of various types of olfactory intelligence applications, including early cancer diagnosis, drug seeking, military operations, and air pollution monitoring.

높은 이방성 에너지를 갖는 교환결합층을 도입한 고밀도 광자기 기록매체의 특성

류호준,서동우,손영준,박용우,표현봉,백문철 한국자기학회 2003 한국자기학회 학술연구발표회 논문개요집 Vol.13 No.1

수정된 외란관측기를 이용한 광디스크 드라이브 서보 시스템

정종일(Jong Il Jeong),정정주(Chung Choo Chung),표현봉(Hyeon-Bong Pyo),박용우(Yong Woo Park) 대한전기학회 2003 대한전기학회 학술대회 논문집 Vol.2003 No.11

표면 촉매 화학 반응을 이용한 크기 조절이 가능한 홀 어레이 제작

박형주 ( Hyung Ju Park ),박정원 ( Jeong Won Park ),이대식 ( Dae-sik Lee ),표현봉 ( Hyeon-bong Pyo ) 한국센서학회 2018 센서학회지 Vol.27 No.1

Low-cost and large-scale fabrication method of nanohole array, which comprises nanoscale voids separated by a few tens to a few hundreds of nanometers, has opened up new possibilities in biomolecular sensing as well as novel frontier optical devices. One of the key aspects of the nanohole array research is how to control the hole size following each specific needs of the hole structure. Here, we report the extensive study on the fine control of the hole size within the range of 500-2500 nm via surface-catalyzed chemical deposition. The initial hole structures were prepared via conventional photo-lithography, and the hole size was decreased to a designed value through the surface-catalyzed chemical reduction of the gold ion on the predefined hole surfaces, by simple dipping of the hole array device into the aqueous solution of gold chloride and hydroxylamine. The final hole size was controlled by adjusting reaction time, and the optimal experimental condition was obtained by doing a series of characterization experiments. The characterization of size-controlled hole array was systematically examined on the image results of optical microscopy, field emission scanning electron microscopy(FESEM), atomic-force microscopy(AFM), and total internal reflection microscopy.