정윤영 교수

Pressure-sensitive electronic skin composed of a hierarchical structural array exhibits outstanding linear and high sensitivity in the pressure range exerted by gentle touch. By virtue of monolayer graphene acting as electrode material, this device can be operated with low voltage. Especially, its high transparency enables an accurate placement of the device on the target position when it is used for health monitoring.

Abstract Flexible and skin-attachable vibration sensors have been studied for use as wearable voice-recognition electronics. However, the development of vibration sensors to recognize the human voice accurately with a flat frequency response, a high sensitivity, and a flexible/conformable form factor has proved a major challenge. Here, we present an ultrathin, conformable, and vibration-responsive electronic skin that detects skin acceleration, which is highly and linearly correlated with voice

We present a new method to manipulate the channel charge density of field-effect transistors using dipole-generating self-assembled monolayers (SAMs) with different anchor groups. Our approach maintains an ideal interface between the dipole layers and the semiconductor while changing the built-in electric potential by 0.41-0.50 V. This potential difference can be used to change effectively the electrical properties of nanoelectronic devices. We further demonstrate the application of the SAM dipo

Flexible materials with sufficient mechanical endurance under bending or folding is essential for flexible electronic devices. Conventional rigid materials such as metals and ceramics are mostly brittle so that their properties can deteriorate under a certain amount of strain. In order to utilize high-performance, but brittle conventional materials in flexible electronics, we propose a novel flexible substrate structure with a low-modulus interlayer. The low-modulus interlayer reduces the surfac

Numerous wearable devices were developed to measure bioelectric signals for continuous healthcare monitoring. The electrode, which interconnects electronics and the human body, significantly affects the signal quality. Although Ag/AgCl electrodes have been commonly used, noble-metal electrodes are more promising in terms of long-term reusability and flexibility. However, the signal-to-noise ratio (SNR) of noble metals is still insufficient for highly accurate biosignal acquisition. In this study

We achieved the lowest contact resistance between a-IGZO and a metal electrode for >30 GHz operation of an oxide semiconductor device. For high-resolution display and high-speed electronic devices, both bulk and contact resistances need to be reduced. In this study, hydrogen plasma was used to lower the contact resistance significantly by modifying the surface of the a-IGZO thin film. The potential barrier width at the interface was decreased by increasing the carrier concentration, and weak M–O

Low-temperature fabrication of thin-film dielectrics is essential for various applications including flexible/stretchable electronics, monolithic three-dimensional integrated circuits, and large-area sensors/displays. Silicon dioxide is one of the most extensively used dielectric materials, but conventional deposition methods such as plasma-enhanced chemical vapor deposition and atomic layer deposition require relatively high temperatures. In this study, a high-quality SiO2 thin film was fabrica

For practical applications of organic field-effect transistors (OFETs), the control of threshold voltage (V-TH) is important as different circuits require different electrical characteristics. Here, we demonstrate two types of gate electrode structures to achieve this control, namely, via dual-metal gates and bilayer metal gates. The first approach uses different metallic materials, titanium, and platinum, while the second approach uses different thicknesses in a metal bilayer composed of alumin

We have fabricated high-performance top-contact pentacene field-effect transistors using a nanometer-scale gate dielectric and parylene-C shadow masks. The high-capacitance gate dielectric, deposited by atomic layer deposition of aluminum oxide, resulted in a low operating voltage of 2.5 V. The flexible and conformal parylene-C shadow masks allowed fabrication of transistors with channel lengths of L=5, 10, and 20 μm. The field-effect mobility of the transistors was μ=1.14 (±0.08) cm2/V s on ave

Dysphagia, a swallowing disorder, requires continuous monitoring of throat-related events to obtain comprehensive insights into the patient's pharyngeal and laryngeal functions. However, conventional assessments were performed by medical professionals in clinical settings, limiting persistent monitoring. We demonstrate feasibility of a ubiquitous monitoring system for autonomously detecting throat-related events utilizing a soft skin-attachable throat vibration sensor (STVS). The STVS accurately

Abstract This work presents an analog neuromorphic synapse device consisting of two oxide semiconductor transistors for high‐precision neural networks. One of the two transistors controls the synaptic weight by charging or discharging the storage node, which leads to a conductance change in the other transistor. The programmed weight maintains for more than 300 s as electrons in the storage node are well preserved due to the extremely low off current of the oxide transistor. Ideal synaptic behav

We report a novel concept of graphene transistors on Scotch tape for use in ubiquitous electronic systems. Unlike common plastic substrates such as polyimide and polyethylene terephthalate, the Scotch tape substrate is easily attached onto various objects such as banknotes, curved surfaces, and human skin, which implies potential applications wherein electronics can be placed in any desired position. Furthermore, the soft Scotch tape serves as an attractive substrate for flexible/foldable electr

Numerous wearable sensors have been developed for a variety of needs in medical/healthcare/wellness/sports applications, but there are still doubts about their usefulness due to uncomfortable fit or frequent battery charging. Because the size or capacity of battery is the major factor affecting the convenience of wearable sensors, power consumption must be reduced. We developed a method that can significantly reduce the power consumption by introducing a signal repeater and a special switch that

Abstract Among various photoresponsive materials, organic materials have gained interest due to their low cost, large‐scale yields, and compatibility with flexible substrates. However, their low photoresponsivity compared to inorganic counterparts has been consistently pointed out as a limitation. To address this issue, a highly photoresponsive PM6:Y6/IGZO hybrid phototransistor is presented with a broad spectral range of 450–950 nm. The photoresponse of the device is enhanced by controlling the