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RISS 인기검색어
- 검색키워드
- 저자 : 임영진(Yeongjin Lim) (검색결과 6 건)
- 무료
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임영진(Yeongjin Lim),배주열(Juyeol Bae),신흥주(Heungjoo Shin) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11
Electrochemical signal current can be enhanced by increasing surface area of the electrode or integrating nanopores at the electrode surface. However, complex processes have limited wide-application of nanoporous electrodes. We present a simple method enhancing redox current signal of electrochemcal sensors based on carbon electrodes using oxygen plasm treatment. The carbon electrodes are fabricated using carbon-MEMS process consisting of conventional photolithography and pyrolysis. Micro-sized pores and wrinkles are generated on the surface of negative photoresist structures patterned using an oxygen plasma treatment ahead of pyrolysis. The porous polymer structures were converted into carbon electrodes with nano-sized wrinkles and nanopores via pyrolysis. The geometry of the carbon electrode is determined by the photolithography so that complex shapes of micro/sub-micrometer-sized carbon electrodes can be fabricated. Moreover, the sizes of the carbon nanopores can be controlled depending on the conditions of the oxygen plasma treatment and pyrolysis processes. The electrochemical currents of disc carbon electrodes were enhanced up to 2.6 times compared to a bare carbon electrode by just applying a 200s oxygen plasma treatment before pyrolysis. We expect this novel nanoporous carbon electrodes to be used in a variety of applications of bio-sensors such as sandwich immuno-assay, enzyme-based sensors and non-enzymatic bio-sensors.
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Lift-off 공정을 이용하여 기능화된 공중부유형 탄소 나노와이어 기반 수소 가스 센서 개발
임영진(Yeongjin Lim),이윤정(Yunjeong Lee),신흥주(Heungjoo Shin) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
In this report, we present a highly sensitive hydrogen gas sensor based on a suspended carbon nanowire functionalized with a thin palladium layer which is coated selectively on the suspended wire using a lift-off process. Application of this process to conventional suspended nanostructures is limited because of low structure robustness resulting in stiction phenomenon frequently. The suspended nanowire is fabricated using carbon-MEMS consisting of successive photolithography processes and a single pyrolysis process. The pyrolysis accompanies a volume reduction of carbon posts supporting the suspended nanowire and thus the nanowire exhibits tensile stress resulting in the enhancement of wire robustness enough to overcome surface tension. Owing to the suspended geometry of the carbon nanowire, palladium can be selectively patterned in sub-micrometer-scale resolution using a simple e-beam evaporation process. The nanowire-based sensor shows good sensing capability of hydrogen gas in low concentration down to 20 ppm
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나노임프린트를 이용한 마이크로-나노 혼합 스케일 PMMA 채널 네트워크 제작공정 개발
홍지수(Jisoo Hong),임영진(Yeongjin Lim),신흥주(Heungjoo Shin) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
In this paper, we present the fabrication of mixed-scale PMMA (polymethyl methacrylate) channels consisting of micro- and nano-channels using simple thermal nanoimprint and thermal bonding processes (microchannels: width = ~ 100 ㎛, height = ~ 8 ㎛; nanochannels: width = ~ 700 ㎚, height = ~ 150 ㎚, length = ~ 100 ㎛). In the nanoimprint process, a monolithic mixed-scale carbon structure was used as a mold. The monolithic carbon mold was fabricated using carbon-MEMS consisting of two-step photolithography processes for patterning a polymer structure and one step pyrolysis process for converting polymer to carbon. In pyrolysis, polymer structures shrank dramatically and thus micro-sized polymer structures could be converted into sub-micro-/nano-sized carbon structures. The shape of the monolithic mixed-scale carbon mold was pressed into a PMMA sheet while the polymer sheet was heated. After demolding the carbon mold from the patterned PMMA sheet, the patterned channel networks on the PMMA sheet was sealed by bonding another thin PMMA sheet to the patterned PMMA sheet with pressure and heat subsequent to an oxygen plasma treatment. The pyrolyzed carbon mold could be easily demolded because of its curved side walls resulting from anisotropic volume reduction in pyrolysis. This special geometry and good robustness of the carbon mold ensured reproducibility in nanoimprint process. PMMA has higher Young’s modulus compared to PDMS (polydimethylsiloxane) that is widely used for the nano-channel fabrication so that the PMMA channels ensure consistent channel fabrication and nanofluidic experiments without channel collapse originated problems.
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마이크로-나노 혼합 스케일 채널 제작을 위한 주형 제작 공정 개발
이윤정(Yunjeong Lee),임영진(Yeongjin Lim),신흥주(Heungjoo Shin) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
We introduce a novel batch fabrication process for the mixed-scale carbon network structures that work as molds in soft lithography for channel network including microchannels and nanochannels. A carbon-MEMS process consisting of two serial photolithography steps and a single pyrolysis step was utilized to fabricate the mixed-scale carbon structures. Since the pyrolysis accompanies enormous volume shrinkage up to 80%, micro-scale polymer structures are easily converted to nano-scale carbon structures and thus carbon structures in mixed-scale can be fabricated in batch and cost-effective ways. The hydrophobic surface and inclined side wall profile of the pyrolyzed carbon mold structure enhance the efficiency of demolding process. Micro-sized holes are patterned periodically along the microchannel molds to produce micro-pillars for avoiding the collapse of the channels made of polydimethylsiloxane (PDMS).
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마이크로 채널 집적을 통한 카본 빗살무늬 나노전극 어레이 기반 전기화학 센서의 민감도 향상
허정일(Jeong-Il Heo),임영진(Yeongjin Lim),이병준(Byungjune Lee),신흥주(Heungjoo Shin) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
In this paper, a highly sensitive and simple electrochemical sensing platform which consists of carbon interdigitated array (IDA) nanoelectrodes integrated in a PDMS microchannel is introduced. In previous studies, the prospect of electrochemical sensors using carbon IDA nanoelectrodes capable of amplifying current signal by 29 times was demonstrated. This electrochemical signal amplification is based on redox cycling of redox species between the fingers of the IDA nanoelectrodes each of that experiences distinct redox reactions, that is reduction or oxidation depending on electrode potential. The redox cycling based signal amplification can be further enhanced by integrating a microchannel on top of the IDA nanoelectrodes. This is because the redox cycling effect is maintained steady while non-reversible species depletes faster as the microchannel size reduces. We present highly sensitive electrochemical sensors which have more than 2 order electrochemical signal amplification (>100) using only conventional soft lithography and carbon-MEMS process.
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