Se-Hyuk Yeom

Highly sensitive nano-porous lattice biosensor based on localized surface plasmon resonance and interference

We propose a design for a highly sensitive biosensor based on nanostructured anodized aluminum oxide (AAO) substrates. A gold-deposited AAO substrate exhibits both optical interference and localized surface plasmon resonance (LSPR). In our sensor, application of these disparate optical properties overcomes problems of limited sensitivity, selectivity, and dynamic range seen in similar biosensors. We fabricated uniform periodic nanopore lattice AAO templates by two-step anodizing and assessed their suitability for application in biosensors by characterizing the change in optical response on addition of biomolecules to the AAO template. To determine the suitability of such structures for biosensing applications, we immobilized a layer of C-reactive protein (CRP) antibody on a gold coating atop an AAO template. We then applied a CRP antigen (Ag) atop the immobilized antibody (Ab) layer. The shift in reflectance is interpreted as being caused by the change in refractive index with membrane thickness. Our results confirm that our proposed AAO-based biosensor is highly selective toward detection of CRP antigen, and can measure a change in CRP antigen concentration of 1 fg/ml. This method can provide a simple, fast, and sensitive analysis for protein detection in real-time.

Nanostructures in biosensor-a review

In the 21(st) century, it is widely recognized that along with information technology (IT) and biotechnology (BT), nanotechnology (NT) will be a key field of science that will drive future developments. NT is expected to allow innovations in industrial fields such as electrical and electronics, biochemistry, environment, energy, as well as materials science by enabling the control and operation of materials at the atomic and molecular levels. In particular, the application of NT in the field of biochemistry is now enabling the realization of previously unachievable objectives.This review discusses the growth, synthesis, and biocompatible functionalization of each materials, with an emphasis on 1D nanomaterials such as CNTs, inorganic nanowires (made of Si, metals, etc.), and conducting polymer nanowires, along with 0D nanomaterials such as nanoparticles. This review also investigates the sensing principle and features of nanobiosensors made using the abovementioned materials and introduce various types of biosensors with nanostructure 0-D and 1-D. Finally, the review discusses future research objectives and research directions in the field of nanotechnology.

Fiber-optic multi-sensor array for detection of low concentration volatile organic compounds

In this paper, we proposed a new type high sensitive volatile organic compounds (VOCs) gas sensor array that is based on the pulse width modulation technique. Four different types of solvatochromic dyes and two different types of polymers, were used to make the five different types of sensing membranes. These were deposited on the five side-polished optical fibers by a spin coater to make the five different sensing elements of the array. In order to ascertain the effectiveness of the sensors, five VOC gases were tested. Finally, principal component analysis (PCA) has been used to discriminates different types of VOCs.

MOSFET–BJT hybrid mode of the gated lateral bipolar junction transistor for C-reactive protein detection

In this study, we propose a novel biosensor based on a gated lateral bipolar junction transistor (BJT) for biomaterial detection. The gated lateral BJT can function as both a BJT and a metal-oxide-semiconductor field-effect transistor (MOSFET) with both the emitter and source, and the collector and drain, coupled. C-reactive protein (CRP), which is an important disease marker in clinical examinations, can be detected using the proposed device. In the MOSFET-BJT hybrid mode, the sensitivity, selectivity, and reproducibility of the gated lateral BJT for biosensors were evaluated in this study. According to the results, in the MOSFET-BJT hybrid mode, the gated lateral BJT shows good selectivity and reproducibility. Changes in the emitter (source) current of the device for CRP antigen detection were approximately 0.65, 0.72, and 0.80 μA/decade at base currents of -50, -30, and -10 μA, respectively. The proposed device has significant application in the detection of certain biomaterials that require a dilution process using a common biosensor, such as a MOSFET-based biosensor.

Variable wavelength surface plasmon resonance (SPR) in biosensing

In this study, we fabricated a novel variable wavelength surface plasmon resonance (SPR) sensor, which detects resonance conditions such as a maximum attenuation wavelength, measuring change of microscopic refractive index. Such a change was measured to detect a salmonella antigen-antibody reaction and a penicillinase-penicillin reaction. Our experiments were performed after immobilizing a salmonella antibody on the sensor chip. We measured the shift in resonant wavelength during the antigen-antibody reaction for 30 min by injecting 5 x 10(7) cells/ml concentration of salmonella antigen solution into the sample chamber. Also, after immobilizing penicillinase on the sensor chip, we measured the shift in resonant wavelength during the reaction. Penicillin solution at 10mM was injected into the sample chamber. The shift of resonant wavelength for each experiment was measured using a white light source, multimode optical fiber, a part of sensor chip and an optical spectrum analyzer. As a result, the resonant wavelength shifted about 0.26 nm/min owing to the salmonella antibody-antigen reaction. Thus, we could detect the change in wavelength (0.8 nm/min) through the interaction of penicillin and penicillinase for 15 min using variable wavelength SPR sensor.

Enhanced Charge Transfer of QDs/Polymer Hybrid LED by Interface Controlling

We propose a quantum dots (QDs)/poly(N-vinylcarbazole) (PVK) hybrid light-emitting diode (LED) to improve the electron and hole confinement in the QDs layer. QDs used as monochromatic emitters are dispersed in a PVK matrix with a wide bandgap for quantum wells. The HOMO and LUMO level of the PVK can act as a hole transport buffer and an electron-blocking buffer in the hybridized layer. We fabricate an LED using a simplified QDs/PVK hybrid emissive layer (EML) and compare its performance with that of the hybrid LED with controlled QDs concentration. From the result, it is found that the 1.0 wt% QDs within the PVK hybrid LED show the best performance among the compared LEDs, with a luminance of 5989

Substrate Heated Spray-Deposition Method for High Efficient Organic Solar Cell: Morphology Inspection

{\rm cd}/{\rm m}^{2}

Enhancement of Active Layer Characteristics with Solvent Spray Annealing Treatment for Organic Solar Cell

and an efficiency of 4.2 cd/A. The efficient energy transfer and performance of the QDs/PVK hybrid EML are highly depended on the doping concentration of the QDs.

Sensitivity Alterable Biosensor Based on Gated Lateral BJT for CRP Detection

We report a general approach involving the heating of glass substrates for fabricating spray-coated organic photovoltaic cells. We heated a substrate was heated to temperatures of 50, 100, and 150 °C during the spray-coating process and observed different morphology of the active layer. It was found that the morphology influenced the performance of the organic solar cell. The solar cell subjected to spray coating at a substrate temperature of 150 °C showed a power conversion efficiency (PCE) of ~3.84%, an open voltage of ~0.61 V, and a short current density of ~20 mA/cm2. After optimizing post annealing, we obtained the PCE up to 4.3%.

P2.3.3 VOC gas detection using solvatochromic dye coated side polished optical fiber

This paper presents an active layer treatment method that is referred to as solvent spray annealing. Spray-deposited organic solar cells were fabricated, and then, solvent spray annealing was performed on the active layer with dichlorobenzene while the substrate was heated at 150 °C. The absorbance and crystallinity of the active layer improved after solvent spray annealing. Further, the spray-deposited organic solar cell treated by solvent spray annealing, in which the fill factor and current density dominantly increased, achieved an efficiency of 1.87%, whereas a pristine sample showed an efficiency of 1.1%.