• Journal of Biosystems Engineering
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• 제37권3호
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• pp.209-213
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• 2012

Purpose: This study was performed to develop a simple, disposable thin-film optical nitrate sensor. Methods: The sensor was fabricated by applying a nitrate-selective polymer membrane on the surface of a thin polyester film. The membrane was composed of polyvinylchloride (PVC), plasticizer, fluorescent dye, and nitrate-selective ionophore. Fluorescence intensity of the sensor increased on contact with a nitrate solution. The fluorescence response of the optical nitrate sensor was measured with a commercial fluorospectrometer. Results: The optical sensor exhibited linear response over four concentration decades. Conclusions: Nitrate ion concentrations in plant nutrient solutions can be determined by direct optical measurements without any conditioning before measurements.

• 한국환경과학회지
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• 제29권8호
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• pp.801-808
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• 2020

In this study, an effective fluorescence pH sensor based on conjugated polyelectrolyte micelles (CPMs) was devised for detecting extremely acidic conditions. An amphiphilic coumarin derivative (CC12-N), a building block, was prepared, into which an ionizable amino group, aryl amine, was incorporated as a potential hydrophilic moiety. This monomer displays self-assembled micelle formation in extremely acidic pH ranges, giving a hydrophobic π-extended conjugated system at the inner part and hydrophilic functionality at the periphery, resulting in efficient fluorescence intensity enhancement. This new micelle-based fluorescence provides an efficient sensing platform for detecting very low pH values in the presence of competing substances.

• 한국염색가공학회지
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• 제24권4호
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• pp.233-238
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• 2012

The opto-functional materials have been developed as a promising research topic toward the end uses for optical materials and applications. The attractive area in this part was the design of sensor molecules for detecting harmful environmental factors. These harmful factors impart undesired effects on wide range of chemical and biological phenomenon. In this context, many researchers have studied luminescence chemosensor materials. These sensor molecules showed optical signals such as color or fluorescence change by detecting harmful environmental factors. In this study, the novel fluorescence chemosensor 1 has been designed and synthesized through reaction of rhodamine 6g hydrazide and 2-hydroxy-1-naphthaldehyde. The chemosensor 1 had been analyzed by UV-Vis and fluorescence spectrophotometer. We found that this chemosensor 1 has 'off-on' and dual type sensing properties toward $Cu^{2+}$ and $Mg^{2+}$.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권5호
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• pp.432-441
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• 2006

2D fluorescence sensors produce a great deal of spectral data during fermentation processes, which can be analyzed using a variety of statistical techniques. Principal component analysis (PCA) and a self-organizing map (SOM) were used to analyze these 2D fluorescence spectra and to extract useful information from them. PCA resulted in scores and loadings that were visualized in the score-loading plots and used to monitor various fermentation processes with recombinant Escherichia coli and Saccharomyces cerevisiae. The SOM was found to be a useful and interpretative method of classifying the entire gamut of 2D fluorescence spectra and of selecting some significant combinations of excitation and emission wavelengths. The results, including the normalized weights and variances, indicated that the SOM network is capable of being used to interpret the fermentation processes monitored by a 2D fluorescence sensor.

• Journal of Microbiology and Biotechnology
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• 제25권4호
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• pp.503-510
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• 2015

The iLOV protein belongs to a family of blue-light photoreceptor proteins containing a light-oxygen-voltage sensing domain with a noncovalently bound flavin mononucleotide (FMN) as its chromophore. Owing to advantages such as its small size, oxygen-independent nature, and pH stability, iLOV is an ideal candidate over other reporter fluorescent proteins such as GFP and DsRed. Here, for the first time, we describe the feasibility of applying LOV domain-based fluorescent iLOV as a metal sensor by measuring the fluorescence quenching of a protein with respect to the concentration of metal ions. In the present study, we demonstrated the inherent copper sensing property of the iLOV protein and identified the possible amino acids responsible for metal binding. The fluorescence quenching upon exposure to Cu²⁺ was highly sensitive and exhibited reversibility upon the addition of the metal chelator EDTA. The copper binding constant was found to be 4.72 ± 0.84 µM. In addition, Cu²⁺-bound iLOV showed high fluorescence quenching at near physiological pH. Further computational analysis yielded a better insight into understanding the possible amino acids responsible for Cu²⁺ binding with the iLOV protein.

• 센서학회지
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• 제32권5호
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• pp.307-312
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• 2023

To measure the flow velocity and direction in the near field of an unmanned underwater vehicle, an optical measurement unit containing an image sensor and a phosphor-integrated pillar that mimics the neuromasts of a fish was constructed. To analyze pillar movement, which changes with fluid flow, fluorescence image analysis was conducted. To analyze the flow velocity, mean force analysis, which could determine the relationship between the light intensity of a fluorescence image and an external force, and length-force analysis, which could determine the distance between the center points of two fluorescence images, were employed. Additionally, angle analysis that can determine the angles at which pixels of a digital image change was selected to analyze the direction of fluid flow. The flow velocity analysis results showed a high correlation of 0.977 between the external force and the light intensity of the fluorescence image, and in the case of direction analysis, omnidirectional movement could be analyzed. Through this study, we confirmed the effectiveness of optical flow sensors equipped with phosphor-integrated pillars.

• 센서학회지
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• 제6권5호
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• pp.362-368
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• 1997

질소레이저, optode 및 광증배관을 사용하여 우라늄 농도를 원격 실시간으로 측정할 수 있는 방법을 연구하였다. 원격 측정에서 보다 효과적으로 우라늄 형광을 집광할 수 있는 optode를 설계하였으며, optode를 이용하여 우라늄 이온으로부터 나온 형광을 광섬유로 전송하여 광증배관으로 검출하였다. 신호처리에서는 온도 변화와 quencher들의 방해효과가 거의 없는 형광의 초기치를 유도하여 사용하므로 보다 정확한 우라늄 농도를 측정할 수 있었다. 측정 결과 우라늄 농도 변화에 따른 형광 강도의 변화를 쉽게 감지할 수 있었으며, 검출한계는 0.06ppm을 얻었고, $0.1{\sim}2ppm$ 범위에서 직선성이 우수하였다.

• 설비공학논문집
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• 제25권12호
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• pp.668-673
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• 2013

In this study, specimens with nano-sized porous thin films were manufactured by injecting fluorescence solution into the pores. We intended to find out the difference of the fluorescence intensity in each region of the specimen through an experimental apparatus that makes a temperature field. Before conducting experiments, the optimized manufacturing conditions were determined by analysis of all parameters that influence the emission intensity, and the experiments were carried out with the specimens produced in the optimized conditions. Then, the calibration curves of the fluorescence intensity versus temperature were performed by taking the intensity distributions from the specimen in various temperature fields. The surfaces of specimens were coated with Rhodamine-B (Rh-B) fluorescent dye and measured based on the fluorescence intensity. Silica (SiO2) nanoporous structure with 1-um thickness was constructed on a cover glass, and fluorescence dye was absorbed into these porous thin films.

• 분석과학
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• 제8권3호
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• pp.221-227
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• 1995

$Ca^{2+}$에 대하여 특이한 선택성을 보이는 광섬유형광센서에 대하여 연구하였다. 이 센서는 $Ca^{2+}$과 형광성 킬레이트를 형성하는 단백질 Calmodulin(CaM)을 사용하였으며, 두 갈래로 된 광섬유 다발의 끝면에 플루오르세인 이소티오시아네이트로써 형광 표지된 Calmodulin(FCaM)으로 만든 용액을 투석막 안에 넣어서 제작하였다. 이 센서의 감응 메카니즘은 FCaM이 $Ca^{2+}$과 결합하여 킬레이트를 형성할 때에 나타나는 형광 스펙트럼의 이동 현상을 바탕으로 한다. CaM은 $Ca^{2+}$과 결합할 때에 형태변화를 일으키며, 이로 인해 유발되는 FCaM의 형광세기 변화로써 농도를 결정하였다. 광전자증배관으로 형광의 세기를 측정하여 $Ca^{2+}$에 대한 검정곡선을 작성하였으며, 센서의 $Ca^{2+}$에 대한 검출한계와 $Mg^{2+}$, $Eu^{3+}$, $La^{3+}$들에 의한 방해효과, 감응 시간 및 수명을 조사하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2415-2418
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• 2008

Polydiacetylenes (PDAs) are very attractive chemical substances which have distinctive features of color change and fluorescence emission by thermal or chemical stress. Especially, when PDAs contact with solutions of a particular pH, such as a strong alkaline sodium hydroxide (NaOH) solution or a strong acidic hydrogen chloride (HCl) solution, PDAs change their color from non-fluorescent blue to fluorescent red. In this study, we propose a novel method to detect alkaline pH using PDAs and NaOH solutions by hydrodynamic focusing on a microfluidic chip. Preliminary results indicate that the fluorescent intensity of PDAs increases in respond to the NaOH solution concentrations. Also, the fluorescence is quenched back when the PDAs are in contact with a HCl solution. These results are useful in a microfluidic PDA sensor chip design for pH detection.