• 한국기계가공학회지
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• 제21권5호
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• pp.16-21
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• 2022

This study investigates the effect of the deformation on the sensitivity of a flexible polydimethylsiloxane (PDMS) membrane sensor. A PDMS membrane sensor was developed to measure the impact force of a water droplet using a silver nanowire (AgNW). The initial deformation of the membrane was confirmed with the application of a tensile force (i.e., tension) and fixing force (i.e., compressive force) at the gripers, which affects the sensitivity. The experimental results show that as the tension applied to the membrane increased, the sensitivity of the sensor decreased. The initial electrical resistance increased as the fixing force increased, while the sensitivity of the sensor decreased as the initial resistance increased. The movement of the membrane due to the impact force of the water droplet was observed with a high-speed camera, and was correlated with the measured sensor signal. The analysis of the motion of the membrane and droplets after collision confirmed the periodic movement of not only the membrane but also the change in the height of the droplet.

• 한국식품과학회지
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• 제29권6호
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• pp.1075-1081
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• 1997

L-Glutamate를 간편하고 단시간에 측정할 수 있는 glutamate sensor를 개발하기 위하여, glutamate oxidase를 여러 가지 membranes에 고정화 시키는데 적합한 조건과. 그 결과로 얻은 효소 membranes의 특성, 개발한 glutamate sensor의 반응특성 및 glutamate sensor의 정확성을 조사하였다. Glutamate oxidase를 membranes에 고정화 하는데 GA 0.25%, BSA 0.3 mg, 효소 사용량 2.0 units이상이 적당하였다. 고정화 효소의 최적 pH는 6.5이었고, chitosan membrane을 사상한 경우 가장 효소활성이 높았다. 그러나 저장 안정성이나 반응시간 등을 고려하여 preactivated nylon에 고정화시킨 효소 membrane을 glutamate sensor 개발에 사용하였다. Glutamate oxidase를 선택한 membrane에 고정화시켜 효소와 glutamate의 반응산물인 암모니아가 nonactin membrane을 이용한 암모니움이온 전극에 의하여 측정되도록 효소 sensor를 구성하였으며, sensor의 반응시간은 약 2분이었다. Preactivated membrane에 고정화된 효소는 $4^{circ}C$에서 2개월간 저장중 안정한 활성을 보였으며, 이를 사용한 glutamate sensor로 약 250회 측정할 때 까지 활성에 별 변화가 없었다, 개발된 glutamate sensor의 glutamate 측정 농도범위는 $0.1{\sim}5\;mM$ 이었다. Glutamate sensor를 체더 치즈중의 L-glutamate 측정에 응용한 결과는 HPLC로 분석한 결과와 높은 상관관계가 있어, 정확성이 인정되었다.

• 센서학회지
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• 제19권6호
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• pp.497-503
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• 2010

This paper reports a chemomechanical explosive sensor based on a thin polymer membrane. The sensor consists of thin parylene membrane and electrodes. Parylene membrane is functionalized with 4-mercaptophenol which interacts strongly with nitrotoluene based explosives. The membrane deflection caused by molecular interaction between the surface and explosives is monitored by capacitance between the membrane and the substrate. To measure the capacitance, electrodes are formed on the membrane and the substrate. While the previous cantilever system requires a bulky optical measuring system, this purely electric monitoring method offers a compact and effective system. Thus, this explosive sensor can be readily miniaturized and used in the field. The developed sensor can reliably detect dinitrotoluene and its limit of detection is evaluated as approximately 110 ppb.

• KSBB Journal
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• 제10권2호
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• pp.126-130
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• 1995

초산발효 중 에탄올 농도를 On-line으로 측정하기 위해 막가스 센서를 개발하였다. 에탄올이 함유된 발효액은 실리콘막을 통해 투과되고 Carrier gas로 사용된 Synthetic air에 의해 운반되어 반도체형 가 스센서에 감지되도록 설계하였다. 이 때 실리콘막의 두께가 O.5mm이고 Carrier gas의 유속이 20ml/mim이었을 때 막가스 센서의 감도가 가장 높았다. 막가스센셔의 저항치는 측정하고자 하는 에탄올 농 도에 따라 변하였고 이 저항치는 전위차로 변환되어 출력되었다. 제작된 막가스센서의 Calibration CUf ve를 작성하였고 실제로 조업 중인 초산 발효조의 발효액 중 에단올 농도의 On-line 측정이 가능하였 으며 이를 Gas chromatography에 의한 분석치와 비교한 결과 에단올 농도가 $0∼70g/\ell$의 범위에서 서로 상관관계를 나타내어 이러한 막가스센서가 초산발효와 같은 여러 생물공정의 모니터링과 제어에 이용이 가능함을 확인하였다.

• Bulletin of the Korean Chemical Society
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• 제26권4호
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• pp.579-584
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• 2005

The 3-[(2-furylmethylene)amino]-2-thioxo-1,3-thiazolidin-4-one (FTT) was used as an excellent ionophore in construction of a $Zn^{2+}$ PVC-based membrane sensor. The best performance was obtained with a membrane composition of 30% poly(vinyl chloride), 62% nitrobenzen (NB), 3% FTT and 5% sodium tetraphenyl borate (TBP). This membrane sensor shows very good selectivity and sensitivity towards $Zn^{2+}$ over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The membrane sensor revealed a great enhancement in selectivity coefficients for $Zn^{2+}$ ions, in comparison to the previously reported $Zn^{2+}$ membrane sensors. Theoretical studies also showed the selective interaction of TFF and $Zn^{2+}$ ions. The proposed membrane sensor exhibits a Nernstian behavior (with slope of 29.3 ${\pm}$ 0.3 mV per decade) over a wide concentration range (1.0 ${\times}$ $10^{-6}$-1.0 ${\times}$ $10^{-2}$) with a detection limit of 8.5 ${\times}$ $10^{-7}$ M (52 ng mL$^{-1}$). It shows relatively fast response time, in the whole concentration range ($\lt$ 20 s), and can be used for at least 10 weeks in a pH range of 3.0-7.0. The proposed membrane sensor was successfully used in direct determination of $Zn^{2+}$ ions in wastewater of industrial zinc electroplating companies, and also as an indicator electrode in titration with EDTA.

• 센서학회지
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• 제11권5호
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• pp.294-300
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• 2002

In this study, we fabricated thermopile infrared sensor with floating membrane structure. Floating membrane was formed by SOI(Silicon On Insulator) structure. In SOI structure, silicon dioxide layer between top silicon layer and bottom silicon substrate was etched by HF solution, then membrane was floated over substrate. After membrane was floated, thermopile pattern was formed on membrane. By insertion of SOI technology, we could obtain thermal isolation structure easily and passivation process for sensor pattern protection was not required during fabrication process. Then, the amplifier circuit for thermopile sensor was fabricated by using $1.5{\mu}m$ CMOS process. The voltage gain of fabricated amplifier was about two hundred.

• 센서학회지
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• 제28권1호
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• pp.1-6
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• 2019

This paper presents an air flow sensor (AFS) based on a polymer thin film. This AFS primarily consists of a polymer membrane attached to a metal-patterned glass substrate and a temperature-sensing element composed of NiCr. These two components were integrated on a single glass substrate. The AFS measures changes in capacitance caused by deformation of the polymer membrane based on the air flow and simultaneously detects the temperature of the surrounding environment. A readout integrated circuit (ROIC) was also fabricated for signal processing, and an ROIC chip, 1.8 mm by 1.9 mm in size, was packaged with an AFS in the form of a system-in-package module. The total size of the AFS is 1 by 1 cm, and the diameter and thickness of the circular-shaped polymer membrane are 4 mm and $15{\mu}m$, respectively. The rate of change of the capacitance is approximately 11.2% for air flows ranging between 0 and 40 m/s.

• 센서학회지
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• 제33권2호
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• pp.70-77
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• 2024

In this study, a fluorescent ethanol sensor is developed to determine the ethanol concentration in the liquid phase. The sensor is developed using a complex of resazurin (RA)/resorufin (RO) and a hydrotalcite (HT) catalyst in a sol-gel matrix of methyltrimethoxysilane (MTMS) to produce a fluorescent ethanol-sensing membrane (RA/RO^*HT membrane). The operation mechanism of the RA/RO^*HT membrane is based on (i) the oxidation of ethanol to acetaldehyde and (ii) the reduction of RA to RO, through electron flows followed by EtOH ↔ HT ↔ RA/RO ↔ EtOH interactions. These possible redox reactions can lead to an increased fluorescence intensity of the RA/RO^*HT membrane as the ethanol concentration increases. The RA/RO^*HT membrane shows a linear detection range of 1-20 vol.% EtOH with limit of detection (LOD) of 0.178%. Additionally, the RA/RO^*HT membrane has high sensitivity and accuracy for determining the alcohol content in several Korean alcoholic beverages.

• 재활복지공학회논문지
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• 제11권2호
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• pp.133-141
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• 2017

하이브리드 음향센서 (hybrid acoustic sensor)는 음압 기반의 음향센서 (ECM)와 진동 기반의 가속도 센서(acceleration sensor)가 접목된 구조이다. 이는 음향센서의 저주파 대역 감도와 가속도 센서의 고주파 대역 감도를 결합하여 저주파에서 고주파 대역까지 광범위하게 음향을 포집할 수 있다. 본 논문에서는 하이브리드 음향센서에 사용되는 가속도 센서를 제안하였다. 가속도 센서는 음향신호에 의해 발생되는 고막의 진동을 포집한다. 제안된 가속도 센서의 사이즈는 고막의 해부학적 구조와 음향센서인 ECM의 규격을 고려하여 직경 3.2 mm로 결정하였다. 그리고 하이브리드 음향센서가 고감도 광대역 특성을 가지도록 하기 위해서는 가속도 센서의 공진 주파수는 3.5 kHz 부근에서 생성되는 것을 목표로 하였다. 가속도 센서를 구성하는 진동막은 수학적 모델과 유한요소 해석을 통하여 기하학적 구조를 도출하였다. 이를 바탕으로 화학적 식각공정을 이용하여 진동막을 제작하였다. 그리고 제작된 진동막의 주파수 특성을 확인하기 위하여 외력에 의한 진동 측정 실험을 수행하였고, 실험 결과 진동막의 기계적 공진은 3.4 kHz에서 발생되었다. 그러므로 제안한 가속도 센서는 하이브리드 음향센서에 유용하게 활용될 수 있을 것으로 판단된다.

• 센서학회지
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• 제21권3호
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• pp.229-234
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• 2012

The existing permeability measurements based on pressure differential between the polymer membrane that is permeable to measure the amount of oxygen used, but these methods must be kept in a vacuum, and the measurement of the membrane with low permeability in the membrane is too time consuming. In recent years by using electrochemical method polymer membrane currents caused by the amount of oxygen is a measure of how much is used. In this study, apparatus consisting of one anode and six cathodes for multi-oxygen permeability tester used the same number of membranes produced by electrochemical oxygen permeation characteristics. In this study, one silver/silver chloride anode electrochemical method with a hexagonal sensor to put various kinds of polymer membranes with the six oxygen permeability for simultaneous measurement in real-time systems. Six cathodes (Pt), and one of the coil-shaped anode (Ag/AgCl) to form a hexagonal one of the polarographic oxygen sensor in a single measurement system by six sensors. Each sensor for making hexagonal specificity of the sensor to compensate for the conditions obtained in a pure nitrogen gas and pure oxygen gas conditions. With this study, self-developed hexagonal sensor capable of measuring sensors and oxygen permeability tester, for a multi-six different oxygen permeability characteristics of the membrane measured at the same time.