Kwangwoon University

About: Kwangwoon University is a education organization based out in Seoul, South Korea. It is known for research contribution in the topics: Thin film & Resonator. The organization has 4020 authors who have published 8217 publications receiving 104365 citations.

Highly sensitive electrochemical sensor based on environmentally friendly biomass-derived sulfur-doped graphene for cancer biomarker detection

Abstract: Herein, we demonstrate a sulfur-doped reduced graphene oxide (SrGO) product fabricated using an eco-friendly biomass precursor “lenthionine” through a high temperature doping process. The product is used for making a highly sensitive electrochemical sensor for detection of 8-hydroxy-2′-deoxyguanosine (8-OHdG) molecule, which is an important biomarker for oxidative stress, cardiovascular diseases, and cancers. The sulfur-doping amount was regulated and a maximum sulfur content of 2.28 atom% was achieved through controlling the precursor amount. Homogenous presence of large number of sulfur atoms in SrGO in the form of thiophenic ( C S C ) bond produced robust sensitivity (∼1 nM), very wide detection window (20–0.002 μM), good selectivity, high stability and reproducibility, and excellent recoveries for the detection of 8-OHdG biomarker in optimized experimental conditions. The excellent electrochemical sensitivity of SrGO sensor is attributed to the strong electron-donating ability of sulfur that facilitates the electron transfer to the biomolecules in the electrochemical reactions. Thus, the proposed method endorses an excellent platform for the electrochemical detection of 8-OHdG with great ease and reliability.

Wireless, battery-free, flexible, miniaturized dosimeters monitor exposure to solar radiation and to light for phototherapy

Abstract: Exposure to electromagnetic radiation can have a profound impact on human health. Ultraviolet (UV) radiation from the sun causes skin cancer. Blue light affects the body’s circadian melatonin rhythm. At the same time, electromagnetic radiation in controlled quantities has beneficial use. UV light treats various inflammatory skin conditions, and blue light phototherapy is the standard of care for neonatal jaundice. Although quantitative measurements of exposure in these contexts are important, current systems have limited applicability outside of laboratories because of an unfavorable set of factors in bulk, weight, cost, and accuracy. We present optical metrology approaches, optoelectronic designs, and wireless modes of operation that serve as the basis for miniature, low-cost, and battery-free devices for precise dosimetry at multiple wavelengths. These platforms use a system on a chip with near-field communication functionality, a radio frequency antenna, photodiodes, supercapacitors, and a transistor to exploit a continuous accumulation mechanism for measurement. Experimental and computational studies of the individual components, the collective systems, and the performance parameters highlight the operating principles and design considerations. Evaluations on human participants monitored solar UV exposure during outdoor activities, captured instantaneous and cumulative exposure during blue light phototherapy in neonatal intensive care units, and tracked light illumination for seasonal affective disorder phototherapy. Versatile applications of this dosimetry platform provide means for consumers and medical providers to modulate light exposure across the electromagnetic spectrum in a way that can both reduce risks in the context of excessive exposure and optimize benefits in the context of phototherapy.

Deep ECGNet: An Optimal Deep Learning Framework for Monitoring Mental Stress Using Ultra Short-Term ECG Signals.

Abstract: Background: Stress recognition using electrocardiogram (ECG) signals requires the intractable long-term heart rate variability (HRV) parameter extraction process. This study proposes a nov...

Ultrahigh-Sensitivity Mediator-Free Biosensor Based on a Microfabricated Microwave Resonator for the Detection of Micromolar Glucose Concentrations

Abstract: This paper presents a miniaturized microwave-resonator-based ultrahigh sensitivity mediator-free biosensor for determining the level of glucose in deionized-water glucose solutions and human sera using integrated passive device technology on a gallium–arsenide substrate. The proposed glucose biosensor, which consists of cross-coupled stepped-impedance resonators (SIRs), strongly concentrates electromagnetic energy between the coupling regions at a central frequency of 6.53 GHz. The changes in effective permeability $(\mu_{\rm eff})$ and permittivity $(\varepsilon_{\rm eff})$ , which correlate with the variations in the glucose concentration, effectively change the equivalent series inductance and shunt capacitance of the biosensor resonator. This concept was used for the first time to develop an ultrahigh-sensitivity biosensor based on a low $-$ Q microwave resonator. The length of each SIR was meandered width wise, and a meandered-line stub-load was embedded inside the SIR to utilize the equivalent high series inductance and shunt capacitance, respectively. The newly designed present biosensor, which linearly detected glucose level within a wide range of concentration, exhibited an ultrahigh sensitivity (978.7 ${\hbox{MHz/mgmL}}^{-1}$ for sera) at least 4.918 times higher than that of previously reported microwave-resonator-based glucose biosensors, a lower detection limit of 0.01928 $\mu{\hbox{M}}$ , and a rapid detection time of less than 5 s. Supported by S-parameter-based effective-medium-parameter analysis and a sensitivity enhancement principle, the detection accuracy of the proposed biosensor was increased using its glucose-level-dependent spreading of propagation constant $(\gamma)$ and self-resonances of impedance $(Z)$ .