Jongbaeg Kim

Flexible tactile sensors capable of measuring mechanical stimuli via physical contact have attracted significant attention in the field of human-interactive systems. The utilization of tactile information can complement vision and/or sound interaction and provide new functionalities. Recent advancements in micro/nanotechnology, material science, and information technology have resulted in the development of high-performance tactile sensors that reach and even surpass the tactile sensing ability

Abstract Resistive tactile sensors based on changes in contact area have been extensively explored for a variety of applications due to their outstanding pressure sensitivity compared to conventional tactile sensors. However, the development of tactile sensors with high sensitivity in a wide pressure range still remains a major challenge due to the trade‐off between sensitivity and linear detection range. Here, a tactile sensor comprising stacked carbon nanotubes and Ni‐fabrics is presented. The

Although there have been remarkable improvements in stretchable strain sensors, the development of strain sensors with scalable fabrication techniques and which both high sensitivity and stretchability simultaneously is still challenging. In this work, a stretchable strain sensor based on overlapped carbon nanotube (CNT) bundles coupled with a silicone elastomer is presented. The strain sensor with overlapped CNTs is prepared by synthesizing line-patterned vertically aligned CNT bundles and roll

Abstract The development of sensitive, flexible, and transparent tactile sensors is of great interest for next‐generation flexible displays and human–machine interfaces. Although a few materials and structural designs have been previously developed for high‐performance tactile sensors, achieving flexibility, full transparency, and highly sensitive multipoint recognition without crosstalk remains a significant challenge for such systems. This work demonstrates a capacitive tactile sensor composed

A flexible, three-axis carbon nanotube (CNT)–polymer composite-based tactile sensor is presented. The proposed sensor consists of a flexible substrate, four sensing cells, and a bump structure. A CNT–polydimethylsiloxane (PDMS) composite is produced by a solvent evaporation method, and thus, the CNTs are well-dispersed within the PDMS matrix. The composite is directly patterned onto a flexible substrate using a screen printing technique to fabricate a sensor with four sensing cells. When a force

A flexible piezoelectric strain energy harvester that is responsive to multi-directional input forces produced by various human motions is proposed. The structure of the harvester, which includes a polydimethylsiloxane (PDMS) bump, facilitates the effective conversion of strain energy, produced by input forces applied in random directions, into electrical energy. The structural design of the PDMS bump and frame as well as the slits in the piezoelectric polyvinylidene fluoride (PVDF) film provide

A new design of flexible energy harvester to utilize piezoelectric and electrostatic energy conversion mechanisms simultaneously from a single mechanical energy source is proposed. This non-resonant type harvester enables low-frequency mechanical inputs to be converted to electricity, and the polymeric structures make the harvester mechanically flexible, allowing it to be applied to non-planar surfaces. The fabricated harvester generated peak- and average power densities of 159 and 1.79 μW cm−2

Among various metal oxides, titanium dioxide (TiO₂) has received considerable interest as a gas-sensing material owing to its high reliability at high operating temperatures. Nonetheless, TiO₂ generally has low sensitivity to target gases. In particular, TiO₂-based sensors have difficulty in sensitively detecting benzene, toluene, and xylene (referred to as BTX). Moreover, the reported TiO₂-based sensors have not simultaneously satisfied the demand for

The feasibility of ultrasonic bonding for hermetic microelectromechanical systems (MEMS) packaging has been demonstrated utilizing the solid phase vibration and welding process to bond two elements rapidly at low temperature. Two different approaches have been developed including lateral and vertical ultrasonic bonding setups with three sets of material bonding systems: In-to-Au, Al-to-Al, and plastics-to-plastics. The process utilizes purely mechanical vibration energy to enable low temperature

A highly reliable micromechanical contact based on aligned carbon nanotube (CNT) arrays is demonstrated and characterized. The CNT arrays are synthesized directly on three-terminal microelectromechanical systems, and they are adjusted and simultaneously preloaded during the synthetic process, making intimate micromechanical contacts. It is found that the CNT array-to-array contact improves upon conventional solid-to-solid micromechanical contact. Detailed facts of importance to specialist reader

Two-dimensional (2D) nanomaterials have been extensively explored as promising candidates for gas sensing due to their high surface-to-volume ratio. Among many 2D nanomaterials, molybdenum disulfide (MoS₂) is known to be functional in detecting harmful gases at room temperature; therefore, it has been actively studied as a gas sensing material. However, there has been a limitation in recovering the original signal from reacted MoS₂ after exposure to the target gas. This wor

Abstract Paper has attracted considerable interest as a promising pressure‐sensing element owing to its foldability/bendability and deformability due to its high porosity. However, paper‐based tactile sensors reported hitherto cannot achieve high sensitivity and a wide sensing range simultaneously. In this study, a resistive tactile sensor using carbon nanotube‐ and silver nanoparticle‐printed mulberry paper as a pressure‐sensing element and electrodes, respectively, is developed. The rough surf

Abstract Transparent and flexible UV sensors have attracted considerable attention for use in portable/wearable optoelectronic systems. Although UV sensors based on photoactive nanomaterials have been reported for such applications, achieving full transparency and flexibility remains a challenge because they still rely on opaque or brittle electrodes. Here, a fully transparent, flexible, and highly sensitive UV sensor based on 1D carbon nanotubes (CNTs)–2D graphene hybrid is demonstrated. Under

Low-dimensional carbon materials, such as semiconducting carbon nanotubes (CNTs), conducting graphene, and their hybrids, are of great interest as promising candidates for flexible, foldable, and transparent electronics. However, the development of highly photoresponsive, flexible, and transparent optoelectronics still remains limited due to their low absorbance and fast recombination rate of photoexcited charges, despite the considerable potential of photodetectors for future wearable and folda