정운룡 교수

Feeling temperature and touch The range of receptors in our skin make it possible to sense when we are touching an object and also gives us a general sense of the temperature of that object. Achieving this in an artificial skin-like material has been a challenge because most of the approaches for sensing touch are themselves temperature sensitive. You et al. studied the ion relaxation dynamics in a conductive elastomeric film (see the Perspective by Liu). They show that the ion relaxation time c

Abstract The triboelectric nanogenerator (TENG) is a new type of energy generator first demonstrated in 2012. TENGs have shown potential as power sources for electronic devices and as sensors for detecting mechanical and chemical stimuli. To date, studies on TENGs have focused primarily on optimizing the systems and circuit designs or exploring possible applications. Even though triboelectricity is highly related to the material properties, studies on materials and material designs have been rel

Mesoporous CuO particles threaded with carbon nanotubes are suggested as a novel class of nanocomposite material for a high-performance anode in the lithium-ion batteries. The nanocomposite electrode exhibits a highly reversible capacity (650 mA h g(-1) at 0.1 C rate) and an excellent C rate capability (580 mA h g(-1) at 5 C, and 500 mA h g(-1) at 10 C).

PSS) into a solution-processed highly deformable viscoelastic polymer is presented. Rapid self-healing of conductivity, customer-designed LEDs with complex micro-patterns, and foldable stretchable LEDs are demonstrated.

We have studied the chemical transformations in ultrathin chalcogenide nanowires with an aim to understand the parameters that control the morphology and crystal structure of the product. Ultrathin Te nanowires were transformed into Ag2Te nanowires with preservation of the single crystallinity. The Ag2Te nanowires were then converted into CdTe, ZnTe, and PbTe using cation-exchange reactions, and the CdTe nanowires were further transformed into PtTe2 nanotubes. On the basis of the solubility prod

Surfactant-free nanoflakes of n-type Bi2 Te3 and Bi2 Se3 are synthesized in high yields. Their suspensions are mixed to create nanocomposites with heterostructured nanograins. A maximum ZT (0.7 at 400 K) is achieved with a broad content of 10-15% Bi2 Se3 in the nanocomposites.

With the recent progress made in wearable electronics, devices now require high flexibility and stretchability up to large strain levels (typically larger than 30 % strain). Wearable strain sensors or deformable strain sensors have been gaining increasing research interest because of the rapid development of electronic skins and robotics and because of their biomedical applications. Conventional brittle strain sensors made of metals and piezoresistors are not applicable for such stretchable sens

A new strategy to measure the apex cardiogram with electronic skin technology is presented. An electronic skin apexcardiogram sensor, which can compensate the conventional electrocardiogram for cardiac diagnosis, is demonstrated through a highly sensitive and stretchable strain sensor with gold-nanoparticle composites.

High-performance organic field-effect transistors (OFETs) based on polyelectrolyte gate dielectric and electrospun poly(3-hexylthiophene) (P3HT) nanofibers were fabricated on a flexible polymer substrate. The use of UV-crosslinked hydrogel including ionic liquids for the insulating layer enabled fast and large-area fabrication of transistor arrays. The P3HT nanofibers were directly deposited on the methacrylated polymer substrate. During UV irradiation through a patterned mask, the methacrylate

A stretchable polymer channel layer for organic field-effect transistors is obtained by spin-coating a blend solution of polythiophene and rubber polymer. A network of the polythiophene nanofibril bundles surface-embedded in the rubber matrix allows large stretchability of the polythiophene film layer.

Multilayered Au nanosheets are suggested as a novel class of material for fabricating stretchable electrodes suitable for organic-based electronic devices. The electrodes show no difference in resistivity during repeated stretching cycles of up to ϵ = 40%.