김선국 교수

In this paper, we have demonstrated the dual role of boron doping in enhancing the device performance parameters as well as the device stability in low temperatures (200 °C) sol-gel processed ZnO thin film transistors (TFTs). Our studies suggest that boron is able to act as a carrier generator and oxygen vacancy suppressor simultaneously. Boron-doped ZnO TFTs with 8 mol. % of boron concentration demonstrated field-effect mobility value of 1.2 cm2 V−1 s−1 and threshold voltage of 6.2 V, respectiv

Abstract Wearable on‐skin electronic devices that can monitor temperature in real time are of significant interest for personalized mobile health monitoring. Here, a flexible temperature sensor directly patterned by laser‐induced carbonization on Kapton polyimide films integrated with flexible printed circuit boards is reported. The proposed sensor design possessing high resistance values exhibits high‐linear and stable response to temperatures when integrated with flexible printed circuit board

Physiological monitoring through skin patch stretchable devices has received extensive attention because of their significant findings in many human-machine interaction applications. In this paper, we present novel nature-inspired, kiri-spider, serpentine structural designs to sustain mechanical deformations under complex stress environments. Strain-free mechanical structures involving stable high areal coverage (spiderweb), three-dimensional out-of-plane deformations (kirigami), and two-dimensi

Electronic skin sensors prepared from biocompatible and biodegradable polymeric materials significantly benefit the research and scientific community, as they can reduce the amount of effort required for e-waste management by deteriorating or dissolving into the environment without pollution. Herein, we report the use of polylactic acid (PLA)-a promising plant-based bioplastic-and highly transparent, conductive, biocompatible, and flexible poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (

The technological ability to detect a wide spectrum range of illuminated visible-to-NIR is substantially improved for an amorphous metal oxide semiconductor, indium gallium zinc oxide (IGZO), without employing an additional photoabsorber. The fundamentally tuned morphology via structural engineering results in the creation of nanopores throughout the entire thickness of ∼30 nm. See-through nanopores have edge functionalization with vacancies, which leads to a large density of substates near the

On-skin stretchable electronic devices that can acquire electrophysiological signals for controllable human-machine interactions are of considerable importance in wearable robotics applications. The straightforward, large-area fabrication of structurally stretchable electronic sensors processed by ultrafast laser ablation techniques provides great insights into low-cost wearable stretchable sensors. In this article, a patch-based large-area frame-type stretchable sensor array system that covers

Anticounterfeiting tags affixed to products offer a practical solution to combat counterfeiting. To be effective, these tags must be economical, capable of ultrafast production, mass-producible, easy to authenticate, and automatable. We present a universal laser ablation technique that rapidly generates intrinsic, randomly distributed craters (in under a second) on laser-sensitive materials using a nanosecond pulsed infrared laser. The laser and scanning line parameters are balanced to produce r

Stretchable electronic devices have recently gained a lot of attention because of their applications in healthcare and wearable electronics and their other innovative applications.

Deformable 3D structures have emerged to revolutionize next-generation flexible electronics. In this study, a large out-of-plane deformable kirigami-based structure integrated with traditional functional materials has been successfully applied to wirelessly sense mechanical vibration and pressure. Unlike spiral inductor coils that lack mechanical stability, the inductor coils supported with polymer kirigami designs, comprising concentric circles with alternately connected hinges among the consec

The use of biopolymers for realizing economical and eco-friendly triboelectric nanogenerators (TENGs) widens the application prospects of TENGs. Herein, an animal-sourced whey protein isolate (WPI) film, processed and prepared by a simple aqueous solution preparation and drop-casting technique, is applied to demonstrate its potential use in bio-TENGs. With the addition of formaldehyde in WPI, the films result in a free-standing and flexible film, whereas the pure WPI films are difficult to handl

Disposable wearable sensors that ultrathin and conformable to the skin are of significant interest as affordable and easy-to-use devices for short-term recording. This study presents a facile and low-cost method for transferring spray-coated silver nanowire (AgNW) composite films onto human skin using glossy paper (GP) and liquid bandages (LB). Due to the moderately hydrophobic and rough surface of the GP, the ultrathin AgNWs composite film (~200 nm) was easily transferred onto human skin. The A

Abstract Sub‐zero temperature sensors (SZTSs) have potential applications in safely storing COVID‐19 vaccines. Herein, an SZTS based on laser‐induced carbonization (LIC) achieved by a nanosecond infrared laser with a wavelength of 1064 nm is reported. Direct laser writing is adopted for laser‐induced carbon in Kapton polyimide sheets with a thickness of 125 µm. The sensor exhibits a good linear change in resistance to sub‐zero temperatures ranging from 0 to −150 °C, where the coefficient of dete

Abstract The monitoring of saline levels during medication has become a tedious process for practitioners. Regardless of the infusion bag size, real‐time wireless monitoring is essential in the healthcare medical sector. This paper demonstrates a size‐independent infusion bag liquid level monitoring system based on highly stretchable (>100% tensile strain) hydrogel‐based electrodes. The sensor uses coplanar capacitive electrodes to sense changes in the liquid level and is integrated with a fl

Hybrid electronics require a robust mechanical interface between externally fabricated stretchable sensors and flexible printed circuit boards (FPCBs) to obtain stable electrophysiological information. The most advanced technique for the integration of FPCBs with stretchable sensors is anisotropic conductive film bonding. Fabricating high-performance sensors requires microfabrication techniques, such as photolithography and etching, which are cumbersome and expensive. Therefore, a sensor fabrica