• 센서학회지
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• 제32권4호
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• pp.207-212
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• 2023

H₂S is a toxic and harmful gas, even at concentrations as low as hundreds of parts per million; thus, developing an H₂S sensor with excellent performance in terms of high response, good selectivity, and fast response time is important. In this study, an H₂S sensor with a high response and fast response time, consisting of a sensing material (SnO₂), an electrode, a temperature sensor, and a micro-heater, was developed using micro-electro-mechanical system technology. The developed H₂S sensor with a micro-heater (circular type) has excellent H₂S detection performance at low H₂S concentrations (0-10 ppm), with quick response time (<16 s) and recovery time (<65 s). Therefore, we expect that the developed H₂S sensor will be considered a promising candidate for protecting workers and the general population and for responding to tightened regulations.

• 대한화학회지
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• 제64권2호
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• pp.74-78
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• 2020

산성 영역에서 작동하는 고감도 형광 pH 센서막을 제조하기 위하여 실란화된 유리 표면 상에 push-pull 공액 염료(DCMP)를 공유결합에 의해 고정화하였다. DCMP 유도체(DCMA), 2-hydroxyethyl methacrylate (HEMA)및 triethylene glycol dimethacrylate의 혼합물을 광개시 공중합하여 pH 감응성 형광센서막을 제조하였다. 분광학적 측정 결과, pH 2.0-5.0 사이에서 pH가 증가함에 따라 센서막의 흡광도가 증가하였으며, 같은 pH 범위에서 pH 증가에 따라 센서막의 형광 세기도 약 50배 정도 증가하였다. 산성 조건에서 pH 변화에 대한 센서막의 감응은 가역적이고 재현성이 우수하였다. 또한 센서막은 20-50초 사이의 비교적 짧은 감응 시간과 여러 금속이온 존재에서 수소 이온에 대해 높은 선택성을 나타내었다.

• Transactions on Electrical and Electronic Materials
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• 제13권1호
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• pp.27-30
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• 2012

This paper proposes a micro gas sensor for measuring $H_2S$ gas. This is based on a $SnO_2$-CuO multi-layer thin film. The sensor has a silicon diaphragm, micro heater, and sensing layers. The micro heater is embedded in the sensing layer in order to increase the temperature to an operating temperature. The $SnO_2$-CuO multi layer film is prepared by the alternating deposition method and thermal oxidation which uses an electron beam evaporator and a thermal furnace. To determine the effect of the number of layers, five sets of films are prepared, each with different number of layers. The sensitivities are measured by applying $H_2S$ gas. It has a concentration of 1 ppm at an operating temperature of $270^{\circ}C$. At the same total thickness, the sensitivity of the sensor with multi sensing layers was improved, compared to the sensor with one sensing layer. The sensitivity of the sensor with five layers to 1 ppm of $H_2S$ gas is approximately 68%. This is approximately 12% more than that of a sensor with one-layer.

• 센서학회지
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• 제31권5호
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• pp.348-352
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• 2022

Hydrogen gas (H₂) which is odorless, colorless is attracting attention as a renewable energy source in varions applications but its leakage can lead to disastrous disasters, such as inflammable, explosive, and narcotic disasters at high concentrations. Therefore, it is necessary to develop H₂ gas sensor with high performance. In this paper, we confirmed that H₂ gas detection ability of SnO₂ based H₂ gas sensor along with thermal treatment effect of SnO₂. Proposed SnO₂ based H₂ gas sensor is fabricated by MEMS technologies such as photolithgraphy, sputtering and lift-off process, etc. Deposited SnO₂ thin films are thermally treated in various thermal treatement temperature in range of 500-900 ℃ and their H₂ gas detection ability is estimatied by measuring output current of H₂ gas sensor. Based on experimental results, fabricated H₂ gas sensor with SnO₂ thin film which is thermally treated at 700 ℃ has a superior H₂ gas detection ability, and it can be expected to utilize at the practical applications.

• 센서학회지
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• 제15권2호
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• pp.127-133
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• 2006

Recent studies demonstrated the ability of carbon nanotube (CNT) to promote electron transfer reactions of important compounds and to impart higher stability onto electrochemical sensors. CNT-based sensors measured by hydroxyl radical concentration or pH value suggest great promise for biosensors. This paper describes a new method for fabricating a very simple and inexpensive pH sensor compose of single walled-carbon nanotubes (SW-CNTs) using an ultra-precision spray. CNT-based sensor shows pH sensitivity in buffer solution at different pH range. Our experimental results show the sensor responses to pH buffer solution and the conductance of depends on the pH values. These results support application possibility of SW-CNTs based pH sensor for mass production.

• 한국식품위생안전성학회지
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• 제32권6호
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• pp.447-454
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• 2017

본 연구의 목적은 식품 제조 중 표백 및 살균에 사용되는 과산화수소($H_2O_2$)의 잔류 농도 검출에 활용 될 수 있는 유리탄소전극 기반의 바이오센서의 개발이다. 미국 FDA 및 국내 식품의학안전처 등 식품 용 과산화수소(food grade $H_2O_2$)는 국내외적으로 35% $H_2O_2$ 수용액으로 규정한다. 연구에서 개발한 바이오센서는 감응 물질로 사용된 horseradish peroxidase를 graphene oxide와 aniline과 함께 biocomposite를 형성시킨 후 중성 pH에서 본 연구에서 새롭게 개발된 전기화학적 증착법을 수행하여 개발되었다. 센서구조 및 특성 평가를 위하여 SEM, 순환 전압 전류법 등을 수행하였으며 본 연구에서 개발된 바이오센서는 $10-500{\mu}M$ 농도의 $H_2O_2$에 대하여 직선상의 농도 의존적인 반응을 나타내었으며 최저 검출 한계는 $0.12{\mu}M$으로 산출되었다. 본 연구에서 개발된 센서의 전략적 가치는 향후 오징어포, 건어물 등 널리 유통되는 식품 중에 함유된 식품용 $H_2O_2$ 미량을 현장에서 쉽게 분석 할 수 있어서 비용-효과적 측면에서 그 가치가 우수하다는 것을 제시한다.

• 한국수소및신에너지학회논문집
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• 제8권4호
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• pp.145-154
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• 1997

Pd, Pd-Rh 게이트 MOS센서의 $H_2$, $H_2S$ 검지특성과 Pd박막의 중착조건이 감지특성에 미치는 영향에 대해서 조사하였다. rf power의 증가와 증착온도의 증가는 모두 센서의 감도와 초기반응속도를 감소시켰으며 rf power의 변화보다는 증착온도의 변화에 의한 효과가 현저하였다. Pd-Rh 센서의 경우 순수한 Pd 센서에 비해 감도가 낮았으며 Rh의 양이 증가할수록 감도는 감소하였다. Pd-Rh 센서에서 $H_2$가 $H_2S$보다 더 뛰어난 감도를 보여주었다. rf power, 증착온도, 기판의 변화가 MOS센서의 감도나 초기반응속도 등의 센서특성에 영향을 미친다는 사실을 확인할 수 있었다.

• 센서학회지
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• 제7권4호
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• pp.271-278
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• 1998

ISFET를 바탕으로 한 포도당 센서일 경우에 저감도, 드리프트 현상, 긴 응답시간의 문제점들을 가지고 있다. 이러한 이유로, ISFET 포도당센서에 백금 엑츄에이터(Pt actuator)를 내장시켜 반응부산물인 $H_2O_2$를 전기분해하는 전류법적인 엑츄에이션(amperometric actuation) 기법을 도입하여 감도를 높였다. 또한 출력신호의 기준선(baseline)을 확인한 후, $H_2O_2$ 전기분해에 의한 pH 변화분만을 검출하여 출력신호로 사용하는 새로운 측정법을 고안하여 심각한 드리프트를 배제하였다. 이러한 전류법적 엑츄에이션과 측정 기술로써 ISFET 포도당 센서의 동작특성이 개선되었다. 제작된 ISFET 포도당센서는 포도당 농도에 따른 응답의 크기가 30mM의 인산완충용액인 PBS(phosphate buffer solution)에서 약 26mV/decade의 높은 감도와 선형성을 보였다. 이 센서를 사용하여 높은 정밀도를 갖는 휴대용 포도당 측정기를 개발하고 그 특성을 평가하였다.

• 센서학회지
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• 제31권2호
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• pp.85-89
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• 2022

We investigated a pH sensor using an Indium tin oxide (ITO) nanoparticle (NP) film printed on a flexible substrate. First, the printing precision and mechanical stability of the ITO-printed film were investigated. In particular, the factors that influence the crystallinity of ITO films were studied using X-ray diffraction pattern analysis. The response of the ITO pH sensor was calibrated using a series of standard pH solutions (pH 3-11). The pH values of various specimens were measured using an ITO pH sensor, and the results were compared with those of various pH measurement methods. As a result of the experiment, the maximum error was approximately ± 0.04 pH (0.4 %) at pH 9, which indicated that the ITO pH sensor is highly suitable for pH measurement. Finally, we used the ITO pH sensor to the measure of general specimens such as solvents and beverages and compared the results in comparison with those obtained from several conventional methods.

• 전기학회논문지
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• 제67권12호
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• pp.1626-1632
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• 2018

In this paper, we describe the fabrication and characterization of a hydrogen peroxide ($H_2O_2$) sensor based on palladium and copper (PdCu) electroplated laser induced graphene (LIG) electrodes. $CO_2$ laser was used to form LIG electrodes on a PI film. This fabrication method allows simple control of the LIG electrode size and shape. The PdCu was electrochemically deposited on the LIG electrodes to improve the electrocatalytic reaction with $H_2O_2$. The electrochemical performance of this sensor was evaluated in terms of selectivity, sensitivity, and linearity. The physical characterization of this sensor was conducted using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), which confirmed that PdCu was formed on the laser induced graphene electrode. In order to increase the sensor sensitivity, the Pd:Cu ratio of the electroplated PdCu was varied to five different values and the condition of highest amperometric current at an identical of $H_2O_2$ concentration was chosen among them. The resulting amperometric current was highest when the ratio of Pd:Cu was 7:3 and this Pd;Cu ratio was employed in the sensor fabrication. The fabricated PdCu/LIG electrode based $H_2O_2$ sensor exhibited a sensitivity of $139.4{\mu}A/mM{\cdot}cm^2$, a broad linear range between 0 mM and 16 mM of $H_2O_2$ concentrations at applied potential of -0.15 V, and high reproducibility (RSD = 2.6%). The selectivity of the fabricated sensors was also evaluated by applying ascorbic acid, glucose, and lactose separately onto the sensor in order to see if the sensor ourput is affected by one of them and the sensor output was not affected. In conclusion, the proposed PdCu/LIG electrode based $H_2O_2$ sensor seems to be suitable $H_2O_2$ sensor in various applications.