• Korean Journal of Materials Research
• /
• v.30 no.10
• /
• pp.515-521
• /
• 2020

Organic-inorganic hybrid perovskite nanocrystals have attracted a lot of attention owing to their excellent optical properties such as high absorption coefficient, high diffusion length, and photoluminescence quantum yield in optoelectronic applications. Despite the many advantages of optoelectronic materials, understanding on how these materials interact with their environments is still lacking. In this study, the fluorescence properties of methylammonium lead bromide (CH₃NH₃PbBr₃, MAPbBr₃) nanoparticles are investigated for the detection of volatile organic compounds (VOCs) and aliphatic amines (monoethylamine, diethylamine, and trimethylamine). In particular, colloidal MAPbBr₃ nanoparticles demonstrate a high selectivity in response to diethylamine, in which a significant photoluminescence (PL) quenching (~ 100 %) is observed at a concentration of 100 ppm. This selectivity to the aliphatic amines may originate from the relative size of the amine molecules that must be accommodated in the perovskite crystals structure with a narrow range of tolerance factor. Sensitive PL response of MAPbBr₃ nanocrystals suggests a simple and effective strategy for colorimetric and fluorescence sensing of aliphatic amines in organic solution phase.

• Bulletin of the Korean Chemical Society
• /
• v.35 no.2
• /
• pp.489-493
• /
• 2014

A phenylbenzimidazole derivatized sensor (L) that behaves as a ratiometric fluorescent receptor for $Zn^{2+}$ in water has been described. In HEPES buffer at pH 7.4, sensor L displays a weak fluorescence emission band at 367 nm. Upon addition of $Zn^{2+}$, the emission intensity at 367 nm is decreased, concomitantly, a new emission band centered at 426 nm is developed, thus facilitates a ratiometric $Zn^{2+}$ sensing behavior. Sensor L binds $Zn^{2+}$ through a 1:1 binding stoichiometry with high selectivity over other metal cations. Sensor L displays a linear response to $Zn^{2+}$ concentration from 0 to $6.0{\times}10^{-5}M$, sensor L also exhibits high sensitivity to $Zn^{2+}$ with a detection limit of $3.31{\times}10^{-7}M$.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.38 no.10
• /
• pp.853-858
• /
• 2014

We propose a fabrication method for polydiacetylene (PDA)-embedded hydrogel microfibers on a microfluidic chip. These fibers can be applied to the detection of cyclodextrines (CDs), which are a family of sugar and aluminum ions. PDA, a family of conjugated polymers, has unique characteristics when used for a sensor, because it undergoes a blue-to-red color transition and nonfluorescence-to-fluorescence transition in response to environmental stimulation. PDAs have different sensing characteristics depending on the head group of PCDA. By taking advantage of ionic crosslinking-induced hydrogel formation and the 3D hydrodynamic focusing effect on a microfluidic chip, PCDA-EDEA-derived diacetylene (DA) monomer-embedded microfibers were successfully fabricated. UV irradiation of the fibers afforded blue-colored PDA, and the resulting blue PDA fibers underwent a phase transition to red and emitted red fluorescence upon exposure to CDs and aluminum ions. Their fluorescence intensity varied depending on the CDs and aluminum ion concentrations. This phase transition was also observed when the fibers were dried.

• Journal of the Microelectronics and Packaging Society
• /
• v.29 no.4
• /
• pp.55-61
• /
• 2022

There is a major interest in diagnostic technology for multiple cancers worldwide. In order to reduce the difficulty of cancer diagnosis, a liquid biopsy technology based on a microfluidic device using trace amounts of biofluids such as blood is being studied. And optical biosensing, which measures the concentration of analytes through fluorescence imaging using biofluids, requires various strategies to improve sensitivity, and specialists and equipment are needed to carry out these strategies. This leads to an increase in diagnostic and production costs, and it is necessary to develop a technology to solve this problem. In this paper, we design and propose a fluorescent multi-cancer diagnostic sensing platform structure that implements passive self-separation technology and molecular recognition activation functions by fluid mixing, only with the geometry and microfluidic phenomena of microchannels based on self-driven flow by capillary force. In order to check the parameters affecting the performance of the plasma separation part of the designed sensor, the hydrodynamic diameter of the channel and the viscosity of the fluid were set as variables to confirm the formation of plasma separation flow through simulation. And finally, we propose an optimal sensor platform structure.

• 한국환경농학회:학술대회논문집
• /
• 2009.07a
• /
• pp.119-126
• /
• 2009

In recent years, research at the Environmental Microbial and Food Safety Laboratory (EMFSL), Agricultural Research Service (ARS) has focused on the development of novel image-based sensing technologies to address agro-food safety concerns, and transformation of these novel technologies into practical instrumentation for industrial implementations. The line-scan-based hyperspectral imaging techniques have often served as a research tool to develop rapid multispectral methods based on only a few spectral bands for rapid online applications. We developed a newer line-scan hyperspectral imaging platform for high-speed inspection on high-throughput processing lines, capable of simultaneous multiple inspection algorithms for different agro-food safety problems such as poultry carcass inspection for wholesomeness and apple inspection for fecal contamination and defect detection. In addition, portable imaging devices were developed for in situ identification of contamination sites and for use by agrofood producer and processor operations for cleaning and sanitation inspection of food processing surfaces. The aim of this presentation is to illustrate recent advances in the above agro.food safety sensing technologies.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.23 no.1
• /
• pp.82-88
• /
• 2021

Sun-induced fluorescence (SIF) retrieval using remote sensing technique has been used in an effort to understand the photosynthetic efficiency and stress condition of vegetation. Although optical devices and SIF retrieval methodologies were established in order to retrieve SIF, the SIF measurements are domestically sparse. SIF data of paddy rice w as measured in Naju, South Korea from June 10, 2020 to October 5, 2020. The SIFs based red (O2A) and far-red (O2B) w ere retrieved using a spectral fitting method and an improved Fraunhofer line depth, and photosynthetically active radiation was also produced. In addition, the SIF data was filtered considering solar zenith angle, saturation conditions, the rapid and sudden change of solar irradiance, and sun glint. The provided SIF data can help to understand a SIF product and the filtering method of SIF data can contribute to producing high-quality SIF data.

• Journal of Sensor Science and Technology
• /
• v.17 no.3
• /
• pp.157-161
• /
• 2008

An optical sensor was developed to detect nanoparticles, turbid materials and microorganisms in water simultaneously. Three different light sources like UV-LED, NIR-LED and laser diode have been employed to develop the optical sensor based on the scattering light and fluorescence light. The sensor system has high selectivity and sensitivity, that it can be used to monitor the quality of drinking water.

• Journal of Biomedical Engineering Research
• /
• v.33 no.3
• /
• pp.114-127
• /
• 2012

Recent technical advancement allows noninvasive measurement of blood glucose. In this literature, we reviewed various noninvasive techniques for measuring glucose concentration. Optical or electrical methods have been investigated. Optical techniques include near-infrared spectroscopy, Raman spectroscopy, optical coherence technique, polarization, fluorescence, occlusion spectroscopy, and photoacoustic spectroscopy. Electrical methods include reverse iontophoresis, impedance spectroscopy, and electromagnetic sensing. Ultrasound, detection from breath, or fluid harvesting technique can be used to measure blood glucose level. Combination of various methods is also promising. Although there are many interesting and promising technologies and devices, there need further researches until a commercially available non-invasive glucometer is popular.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.4
• /
• pp.1061-1064
• /
• 2013

A known $Hg^{2+}$ selective rhodamine B derivatised probe 1 was reinvestigated as a colorimetric and fluorescent probe for $Cu^{2+}$ through changing the applied solvent media. Probe 1 exhibited good selectivity and sensitivity to $Cu^{2+}$ in $CH_3CN-H_2O$ (7:3, v/v, HEPES 10 mM, pH 7.0) solution with a detection limit of $9.74{\times}10^{-7}$ M. The $Cu^{2+}$ sensing event was proved to be irreversible through hydrolysis of 1 to release rhodamine B.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.11
• /
• pp.3696-3700
• /
• 2012

The colorimetric and fluorescent cyanide recognition properties of 2-[(9-ethyl-9H-carbazol-3-yl)methylene]-propanedinitrile (1) in $CH_3CN-H_2O$ (2/1, v/v, HEPES 10 mM, pH = 7.0) solution were evaluated. The optical recognition process of probe 1 exhibited high sensitivity and selectivity to cyanide ion with the detection limit of $2.04{\times}10^{-6}$ M and barely interfered by other coexisting anions. The sensing mechanism of probe 1 is speculated to undergo a nucleophilic addition of cyanide to dicyanovinyl group present in compound 1. The colorimetric and fluorescent dual-modal response to cyanide makes probe 1 has a potential utility in cyanide detection.