• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 II
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• pp.1085-1088
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• 2003

In this work, we fabricated a gas-sensing device based on porous silicon(PS), and its I-V and C-V properties were investigated for sensing alcohol vapor. The structure of the sensor consists of thin Au/Oxidized porous silicon/porous silicon/Silicon/Al, where the silicon substrate is etched anisotropically to be prepared into a membrane shape. As the result, I-V curves showed typical tunneling property, and C-V curves were shaped like those of a MIS (metal-insulator- semiconductor) capacitor, where the capacitance in accumulation was increased with alcohol vapor concentration.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.792-796
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• 2002

In this work, porous silicon(PS) layer is used as a sensing material to detect organic gases. To do this, PS sensors with membrane structure are fabricated. The sensors were made by applying the technologies of membrane formation by anisotropic etching of silicon, and PS layer formation by anodization in HF solution. From fabricated sensors, current-voltage (I-V) curves were measured against ethanol (called alcohol), methanol and acetone gases evaporated from 0.1 to 0.5% solution concentrations at $36^{\circ}C$. As the result, all curves showed rectifying behavior due to a diode structure between Si and PS, and the conductance of sensor devices increased largely with the organic solution concentration at high voltage of 5V.

• 한국전기전자재료학회논문지
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• 제15권11호
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• pp.963-968
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• 2002

In this work, porous silicon (PS) layer is investigated as a sensing material to detect organic vapors such as ethanol (called alcohol), methanol, and acetone in low concentrations. To do this, PS sensors were fabricated. They have a membrane structure and comb-type electrodes were used to detect the change of electrical resistance effectively. PS layer on Si substrates was formed by anodization in HF solution of 25%. From fabricated sensors, current-voltage (Ⅰ-Ⅴ) curves were measured for gases evaporated from 0.1 to 0.5% organic solution concentrations at 36$\^{C}$. As the result, all curves showed rectifying behavior due to a diode structure between Si and the PS layer. The conductance of most sensors increased largely at high voltage of 5V, but the built-in potential on the measured Ⅰ-Ⅴ curve was lowered inversely by the adsorption effect of the organic vapors with high dipole moment.

• 대한기계학회논문집B
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• 제34권2호
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• pp.105-111
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• 2010

양극산화법과 DRIE 법으로 제작된 다공성 실리콘막을 이용하여 두 종류의 전기침투 펌프를 제작하였다. 펌프의 성능은 유기용매를 이용하여 유량과 단위전류당 유량으로 측정하였다. 두 종류 펌프 모두 기존의 다공성 유리막으로 제작된 전기침투 펌프보다 성능이 우월했다. 특히 DRIE 법으로 제작된 다공성 실리콘막은 유량과 단위전류당 유량이 모두 월등한 성능을 보였다. DRIE 법은 널리 알려진 방법이기에 이와 같이 제작된 펌프는 다양한 응용 분야에 비교적 쉽게 적용될 것으로 기대된다.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.1016-1021
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• 2005

A piezoresistive pressure sensor using a silicone rubber membrane has been fabricated on the selectively diffused (100)-oriented n/n+/n silicon substrates by a unique silicon micromachining technique using porous silicon ething. The width, length and thickness of the beam were 120${\mu}m$, 600${\mu}m$ and 7${\mu}m$, respectively and the thickness of the silicone rubber membrane was 40${\mu}m$. By the fusion of silicon beam and silicone rubber membrane, the mechanical strength of the pressure sensor could be highly improved due to smaller shear stress. The effectiveness of the sensor was confirmed through an experiment and FEM simulation in which the pressure sensor was characterized.

• Biotechnology and Bioprocess Engineering:BBE
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• 제8권4호
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• pp.246-251
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• 2003

The blood-brain barrier (BBB) is composed of the brain capillaries, which are lined by endothelial cells displaying extremely tight intercellular junctions. Several attempts at creating an in vitro model of the BBB have been met with moderate success as brain capillary endothelial cells lose their barrier properties when isolated in cell culture. This may be due to a lack of recreation of the in vivo endothelial cellular environment in these models, including nearly constant contact with astrocyte foot processes. This work is motivated by the hypothesis that growing endothelial cells on one side of an ultra-thin, highly porous membrane and differentiating astrocyte or astrogliomal cells on the opposite side will lead to a higher degree of interaction between the two cell types and therefore to an improved model. Here we describe our initial efforts towards testing this hypothesis including a procedure for membrane fabrication and methods for culturing endothelial cells on these membranes. We have fabricated a 1 $\mu\textrm{m}$ thick, 2.0 $\mu\textrm{m}$ pore size, and 55% porous membrane with a very narrow pore size distribution from low-stress silicon nitride (SiN) utilizing techniques from the microelectronics industry. We have developed a base, acid, autoclave routine that prepares the membranes for cell culture both by cleaning residual fabrication chemicals from the surface and by increasing the hydrophilicity of the membranes (confirmed by contact angle measurements). Gelatin, fibronectin, and a 50/50 mixture of the two proteins were evaluated as potential basement membrane protein treatments prior to membrane cell seeding. All three treatments support adequate attachment and growth on the membranes compared to the control.

• 한국전기전자재료학회논문지
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• 제16권12S호
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• pp.1232-1236
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• 2003

In this work, we fabricated a gas-sensing device based on porous silicon(PS), and its C-V properties were investigated for sensing alcohol vapor. The structure of the sensor consists of thin Au/oxidized PS/PS/P-Si/Al, where the p-Si is etched anisotropically to be prepared into a membrane-shape. We used alcohol gases vaporized from different alcohol (or ethanol) solutions mixed with pure water at 36$^{\circ}C$, similarly with an alcohol breath measurement to check drunk driving. As the result, I-V curves showed typical tunneling property, and C-V curves were shaped like those of a MIS (metal-insulator-semiconductor) capacitor, where the capacitance in accumulation was increased with alcohol vapor concentration.

• 센서학회지
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• 제9권6호
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• pp.424-429
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• 2000

실리콘 고무 멤브레인(membrane)에 실리콘 빔(beam)들이 삽입된 형태의 저차압센서를 개발하였다. 제작된 저차압센서는 실리콘 고무(silicone rubber)를 멤브레인으로 사용함으로써 열악한 환경에서도 다양한 응용분야에 적용 가능하도록 하였다. 실리론 고무 멤브레인을 사용한 압저항형 저차압센서는 선택적으로 도핑(doping)된 (100) n/n+/n 웨이퍼 상에 다공질 마이크로머시넝(micro-machining) 기술을 이용하여 제작되었다. 제조된 센서의 감도(sensitivity)는 $0.66{\mu}V/mmHg$이고, 0.1% 이하의 비선형성(non-linearity)을 보였다.

• 한국수소및신에너지학회논문집
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• 제25권4호
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• pp.419-424
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• 2014

Direct ethanol fuel cell has been fabricated with ceramic membrane. A porous silicon carbide (SiC) membrane having approximately 30% porosity has been applied for a direct ethanol proton exchange membrane (DE-PEM) fuel cell. A horizontal type cell having Pt ($18mg/cm^2$) catalyst layer on both side of the ceramic membrane was used for the demonstration test. The ethanol oxidation based-fuel cell stack showed very high voltage (1.289V) and measurable current level (68mA) even though at room temperature.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.241-241
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• 2008

Macrofore formation in silicon and other semiconductors using electrochemical etching processes has been, in the last years, a subject of great attention of both theory and practice. Its first reason of concern is new areas of macropore silicone applications arising from microelectromechanical systems processing (MEMS), membrane techniques, solar cells, sensors, photonic crystals, and new technologies like a silicon-on-nothing (SON) technology. Its formation mechanism with a rich variety of controllable microstructures and their many potential applications have been studied extensively recently. Porous silicon is formed by anodic etching of crystalline silicon in hydrofluoric acid. During the etching process holes are required to enable the dissolution of the silicon anode. For p-type silicon, holes are the majority charge carriers, therefore porous silicon can be formed under the action of a positive bias on the silicon anode. For n-type silicon, holes to dissolve silicon is supplied by illuminating n-type silicon with above-band-gap light which allows sufficient generation of holes. To make a desired three-dimensional nano- or micro-structures, pre-structuring the masked surface in KOH solution to form a periodic array of etch pits before electrochemical etching. Due to enhanced electric field, the holes are efficiently collected at the pore tips for etching. The depletion of holes in the space charge region prevents silicon dissolution at the sidewalls, enabling anisotropic etching for the trenches. This is correct theoretical explanation for n-type Si etching. However, there are a few experimental repors in p-type silicon, while a number of theoretical models have been worked out to explain experimental dependence observed. To perform ordered macrofore formaion for p-type silicon, various kinds of mask patterns to make initial KOH etch pits were used. In order to understand the roles played by the kinds of etching solution in the formation of pillar arrays, we have undertaken a systematic study of the solvent effects in mixtures of HF, N-dimethylformamide (DMF), iso-propanol, and mixtures of HF with water on the macrofore structure formation on monocrystalline p-type silicon with a resistivity varying between 10 ~ 0.01 $\Omega$ cm. The etching solution including the iso-propanol produced a best three dimensional pillar structures. The experimental results are discussed on the base of Lehmann's comprehensive model based on SCR width.