Publications by authors named "Namyun Kim"

This study aims to investigate the association between exposure to toxic indoor chemicals, specifically polyhexamethylene guanidine (PHMG) and oligo(2-(2-ethoxy) ethoxyethyl guanidinium) chloride (PGH), used in humidifier disinfectants, and gestational diabetes mellitus (GDM). We confirmed pregnancy from 2003 to 2017 and identified GDM by linking a cohort of claimants who reported exposure to PHMG/PGH with National Health Insurance Service data. The GDM incidence was calculated, and PHMG/PGH exposure characteristics-exposure status, the humidifier's distance/location, and exposure duration/hours-were investigated.

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Graphene/polymer actuators were developed using bilayer graphene and various polymer substrates for use as transparent, flexible, and robust electrostatic speaker units. Additionally, a resonant frequency shift was induced using a polymer substrate on which various micropatterns were transferred to boost bass. The total sound pressure level (SPL) in the graphene/polymer actuator was measured by a sweep, and the frequency of the spectrum was confirmed to be one-third that of the octave band frequency.

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The recent commercial success of flexible and foldable displays has resulted in growing interest in stretchable electronics which are considered to be the next generation of the optoelectronic technology. Stretchable display technologies are being intensively studied for versatile applications including wearable, attachable, and shape changeable electronics. In this paper, we present high fill factor, stretchable inorganic light-emitting diode (LED) displays fabricated by connecting mini-LEDs and stretchable interconnects in a double-layer modular design.

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Article Synopsis
  • The integration of robotic technologies with flexible electronics allows for dynamic reconfiguration, expanding their potential applications beyond traditional uses.
  • A new film has been developed that can control bending and curvature through localized electrical inputs, maintaining a thin design to minimize stress when manipulated.
  • Examples of this technology's effectiveness include shape-changing displays, self-rollable solar panels, and innovative light art installations.
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Advanced design and integration of functioning devices with secured power is of interest for many applications that require complicated, sophisticated, or multifunctional processes in confined environments such as in human bodies. Here, strategies for design and realization are introduced for multifunctional feedback implants with the bifacial design and silicon (Si) photovoltaics in flexible forms. The approaches provide efficient design spaces for flexible Si photovoltaics facing up for sustainable powering and multiple electronic components for feedback functions facing down for sensing, processing, and stimulating in human bodies.

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Recent advances in soft materials and mechanics activate development of many new types of electrical medical implants. Electronic implants that provide exceptional functions, however, usually require more electrical power, resulting in shorter period of usages although many approaches have been suggested to harvest electrical power in human bodies by resolving the issues related to power density, biocompatibility, tissue damage, and others. Here, we report an active photonic power transfer approach at the level of a full system to secure sustainable electrical power in human bodies.

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Implantable electronics in soft and flexible forms can reduce undesired outcomes such as irritations and chronic damages to surrounding biological tissues due to the improved mechanical compatibility with soft tissues. However, the same mechanical flexibility also makes it difficult to insert such implants through the skin because of reduced stiffness. In this paper, a flexible-device injector that enables the subcutaneous implantation of flexible medical electronics is reported.

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Article Synopsis
  • Monitoring cardiovascular signals like heart rate and blood flow is crucial for patient care, but sensors need to be compatible with soft body tissues for longer use.
  • This paper presents a flexible pulse sensor that can bend easily (2.4 mm radius) and includes small micro-inorganic photodetectors and a red LED for effective monitoring.
  • The sensor can be attached to various body parts, such as fingers and forearms, and is compact enough to be incorporated into a finger ring, showing both electrical and mechanical viability for long-term use.
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Physiological signals provide important information for biomedical applications and, more recently, in the form of wearable electronics for active interactions between bodies and external environments. Multiple physiological sensors are often required to map distinct signals from multiple points over large areas for more diverse applications. In this paper, we present a reusable, multichannel, surface electromyography (EMG) sensor array that covers multiple muscles over relatively large areas, with compliant designs that provide different levels of stiffness for repetitive uses, without backing layers.

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High-performance electronic devices integrated onto unconventional substrates provide opportunities for use in diverse applications, such as wearable or implantable forms of electronic devices. However, the interlayer adhesives between the electronic devices and substrates often limit processing temperature or cause electrical or thermal resistance at the interface. This paper introduces a very simple but effective transfer printing method that does not require an interlayer adhesive.

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A subdermally implantable flexible photovoltatic (IPV) device is proposed for supplying sustainable electric power to in vivo medical implants. Electric properties of the implanted IPV device are characterized in live animal models. Feasibility of this strategy is demonstrated by operating a flexible pacemaker with the subdermal IPV device which generates DC electric power of ≈647 μW under the skin.

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A 53-year-old woman who had undergone total gastrectomy and received adjuvant chemotherapy two months ago underwent adhesiolysis of the small bowel. She presented with sudden desaturation and dyspnea of unknown etiology at postanesthetic care unit. Following ET intubation, the endotracheal tube suction revealed massive hemoptysis.

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