Publications by authors named "Jae Hyun Chung"

A multimodal sensor array, combining pressure and proximity sensing, has attracted considerable interest due to its importance in ubiquitous monitoring of cardiopulmonary health- and sleep-related biometrics. However, the sensitivity and dynamic range of prevalent sensors are often insufficient to detect subtle body signals. This study introduces a novel capacitive nanocomposite proximity-pressure sensor (NPPS) for detecting multiple human biometrics.

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Background: Accurate real-time eye tracking is crucial in oculomotor system research. While the scleral search coil system is the gold standard, its implantation procedure and bulkiness pose challenges. Camera-based systems are affected by ambient lighting and require high computational and electric power.

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Capacitors are essential components in modern electrical systems, functioning primarily to store electrical charges and regulate current flow. Capacitive sensors, developed in the 20th century, have become crucial in various applications, including touchscreens and smart devices, due to their ability to detect both metallic and non-metallic objects with high sensitivity and low energy consumption. The advancement of microelectromechanical systems (MEMS) and nanotechnology has significantly enhanced the capabilities of capacitive sensors, leading to unprecedented sensitivity, dynamic range, and cost-effectiveness.

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Skin-based wearable devices have gained significant attention due to advancements in soft materials and thin-film technologies. Nevertheless, traditional wearable electronics often entail expensive and intricate manufacturing processes and rely on metal-based substrates that are susceptible to corrosion and lack flexibility. In response to these challenges, this paper has emerged with an alternative substrate for wearable electrodes due to its cost-effectiveness and scalability in manufacturing.

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Current point-of-care (POC) screening of Coronavirus disease 2019 (COVID-19) requires further improvements to achieve highly sensitive, rapid, and inexpensive detection. Here we describe an immunoresistive sensor on a polyethylene terephthalate (PET) film for simple, inexpensive, and highly sensitive COVID-19 screening. The sensor is composed of single-walled carbon nanotubes (SWCNTs) functionalized with monoclonal antibodies that bind to the spike protein of SARS-CoV-2.

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The study investigated the osteogenic capacity of a prefabricated periosteal flap created using only skeletonized pedicle transfer without fascia or muscle for vascular induction in rabbit calvarium. A critical-sized bone defect was made in the parietal bone centered on the sagittal suture, and the demineralized bone matrix was implanted. The periosteofascia over the defect was used as a form of prefabricated periosteofascial flap (PPF group, N=10), conventional periosteofascial flap (CPF group, N=10), and nonvascularized free periosteofascial graft (FPG group, N=6).

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Rapid and accurate clinical assessment of hemostasis is essential for managing patients who undergo invasive procedures, experience hemorrhages, or receive antithrombotic therapies. Hemostasis encompasses an ensemble of interactions between the cellular and non-cellular blood components, but current devices assess only partial aspects of this complex process. In this work, we describe the development of a new approach to simultaneously evaluate coagulation function, platelet count or function, and hematocrit using a carbon nanotube-paper composite (CPC) capacitance sensor.

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For point-of-care diagnosis of tuberculosis (TB), current TB diagnostic approaches need to be further improved for achieving an accurate diagnosis that is rapid and low-cost. This paper presents an immuno-resistive sensor on a plastic film for inexpensive, simple TB screening. The sensor is composed of single-walled carbon nanotubes (SWCNTs) functionalized with polyclonal antibodies raised against the MPT64 surface antigen from Mycobacterium tuberculosis (MTB).

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Single-walled carbon nanotubes (SWCNTs) are used as a key component for chemical sensors. For miniature scale design, a continuous printing method is preferred for electrical conductance without damaging the substrate. In this paper, a non-contact capillary pen printing method is presented by the formation of a nanoink bridge between the nib of a capillary pen and a polyethylene terephthalate film.

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Nanostructured tip-shaped biosensors have drawn attention for biomolecule detection as they are promising for highly sensitive and specific detection of a target analyte. Using a nanostructured tip, the sensitivity is increased to identify individual molecules because of the high aspect ratio structure. Various detection methods, such as electrochemistry, fluorescence microcopy, and Raman spectroscopy, have been attempted to enhance the sensitivity and the specificity.

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Multi-drug resistant tuberculosis (MDR-TB) has become a serious concern for proper treatment of patients. As a phenotypic method, dielectrophoresis can be useful but is yet to be attempted to evaluate Mycobacterium tuberculosis complex cells. This paper investigates the dielectrophoretic behavior of Mycobacterium bovis (Bacillus Calmette-Guérin, BCG) cells that are treated with heat or antibiotics rifampin (RIF) or isoniazid (INH).

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(TB) has been a major public health problem, which can be better controlled by using accurate and rapid diagnosis in low-resource settings. A simple, portable, and sensitive detection method is required for point-of-care (POC) settings. This paper studies an amperometric biosensor using a microtip immunoassay for a rapid and low cost detection of (MTB) in sputum.

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Background: A robotic surgery technique of harvesting the latissimus dorsi muscle flap has technical advantages over endoscopic harvest and cosmetic advantages over the open technique. The authors introduce a new transaxillary gasless technique using an articulated long retractor for robot assisted latissimus dorsi flap harvest.

Methods: Twelve robot assisted latissimus dorsi muscle flaps were harvested: 3 cases of delayed reconstruction following tissue expander insertion or breast conserving surgery; 4 cases of immediate reconstruction following nipple-sparing mastectomy; and 5 cases of chest wall deformity correction in patients with Poland syndrome.

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A immunofluorescence microtip sensor was developed for specific detection of Mycobacterium cells in sputum samples by the combination of electric field, streaming flow, and immuno-affinity binding. The detection limit was 200 CFU/mL in human sputum, which was comparable to PCR but without requiring bacteriological culture, centrifugation, or nucleic acid amplification. In spite of the complex nature of physical, chemical, and biological mechanisms, the simple operation of "dipping and withdrawal" of tips will allow for screening by minimally trained personnel within 30 min.

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Foodborne pathogen detection using biomolecules and nanomaterials may lead to platforms for rapid and simple electronic biosensing. Integration of single walled carbon nanotubes (SWCNTs) and immobilized antibodies into a disposable bio-nano combinatorial junction sensor was fabricated for detection of Escherichia coli K-12. Gold tungsten wires (50 µm diameter) coated with polyethylenimine (PEI) and SWCNTs were aligned to form a crossbar junction, which was functionalized with streptavidin and biotinylated antibodies to allow for enhanced specificity towards targeted microbes.

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A simple microfluidic platform was utilized to immobilize glucose oxidase (GOx) in a nonionic micellar scaffold. The immobilization of GOx was verified by using a combination of cryogenic electron microscopy (cryo-EM), scanning electron microscopy (SEM), and ultraviolet spectroscopy (UV) techniques. Chronoamperometric measurements were conducted on nanogel-GOx scaffolds under different glucose concentrations, exhibiting linear amperometric responses.

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Background: The fibular free flap has been used as the standard methods of segmental mandibular reconstruction. The objective of mandibular reconstruction not only includes restored continuity of the mandible but also the recovery of optimal function. This paper emphasizes the advantage of the fibular free flap reconstruction over that of locking mandibular reconstruction plate fixation.

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Over decades, the theoretical and applied mechanics community has developed sophisticated approaches for analysing the behaviour of complex engineering systems. Most of these approaches have targeted systems in the transportation, materials, defence and energy industries. Applying and further developing engineering approaches for understanding, predicting and modulating the response of complicated biomedical processes not only holds great promise in meeting societal needs, but also poses serious challenges.

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Immunoassays analyzing interactions between antigens and antibodies can be affected by capillary action together with binding affinity. This paper studies contact-angle changes of bacterial suspensions on antibody immobilized surfaces. The capillary action and the dried pattern of the bacterial suspensions are analyzed and correlated with specific- and nonspecific bindings between bacteria and antibodies.

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An occupationally safe (biosafe) sputum liquefaction protocol was developed for use with a semi-automated antibody-based microtip immunofluorescence sensor. The protocol effectively liquefied sputum and inactivated microorganisms including Mycobacterium tuberculosis, while preserving the antibody-binding activity of Mycobacterium cell surface antigens. Sputum was treated with a synergistic chemical-thermal protocol that included moderate concentrations of NaOH and detergent at 60°C for 5 to 10 min.

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Micrometre- and submicrometre-size functionalized beads are frequently used to capture targets of interest from a biological sample for biological characterizations and disease diagnosis. The main challenge of the microbead-based assay is in the immobilization of probe molecules onto the microbead surfaces. In this paper, we report a versatile droplet microfluidics method to fabricate alginate microspheres while simultaneously immobilizing anti-Mycobacterium tuberculosis complex IgY and anti-Escherichia coli IgG antibodies primarily on the porous alginate carriers for specific binding and binding affinity tests.

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A single-step concentration and elution method is developed for detection of DNA in buffer, saliva, and blood. A nanotip capturing DNA using an electric field and capillary action is directly dissolved in buffer for qPCR analysis. The concentration yield and the relative parameters are compared with those of a commercial kit.

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Electric detection using a nanocomponent may lead to platforms for rapid and simple biosensing. Sensors composed of nanotips or nanodots have been described for highly sensitive amperometry enabled by confined geometry. However, both fabrication and use of nanostructured sensors remain challenging.

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Rapid and sensitive detection of low-abundance viral particles is strongly demanded in health care, environmental control, military defense, and homeland security. Current detection methods, however, lack either assay speed or sensitivity, mainly due to the nanosized viral particles. In this paper, we compare a dendritic, multi-terminal nanotip ('dendritic nanotip') with a single terminal nanotip ('single nanotip') for dielectrophoretic (DEP) concentration of viral particles.

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