Sangmin Lee 교수

Abstract Using an Al‐foil of thickness ≈18 μm as a substrate and electrode, a piezoelectric nanogenerator (NG) that is super‐flexible in responding to the wavy motion of a very light wind is fabricated using ZnO nanowire arrays. The NG is used to harvest the energy from a waving flag, demonstrating its high flexibility and excellent conformability to be integrated into fabric. The NG is applied to detect the wrinkling of a human face, showing its capability to serve as an active deformation sens

Ultrathin piezoelectric nanogenerator (NG) with a total thickness of ≈16 μm is fabricated as an active or self‐powered sensor for monitoring local deformation on a human skin. The NG was based on an anodic aluminum oxide (AAO) as an insulating layer grown on a thin Al foil by anodization, on which a thin film made of aligned ZnO nanowire compacted arrays is grown by solution chemistry. The performance of the NG is characterized with the assistance of the finite element method (FEM) simulation. T

Abstract As interest in triboelectric nanogenerators (TENGs) continues to increase, some studies have reported that certain limitations exist in TENG due to high potential difference, resulting in air breakdown and field emission. In addition, with known limitations such as extremely low voltage at low external resistance, a breakthrough is required to overcome the limitations of TENG. Here, a new TENG mechanism is reported, utilizing ion‐enhanced field emission (IEFE). Using a simple IEFE‐induc

Abstract Triboelectric nanogenerators (TENGs) can convert a mechanical energy input to an electric energy output through Maxwell's displacement current. By increasing the electrical output and overcoming the mechanical limitations of TENGs, such devices can be used as an auxiliary power source for portable electronics. Nevertheless, the generation mechanism and structure must be optimized to compensate for the electrical and mechanical limitations of TENGs. This paper reports on a nonpolar liqui

Abstract Transmission of pathogens via respiratory droplets can spread infections such as COVID‐19. Wearing a mask hinders the spread of COVID‐19 infection and has become mandatory in some cases. Although most masks are affordable and disposable, continual daily replacement is required due to their performance deterioration caused by washing and contamination. Hence, a urethane‐reactive coating material comprising perfluoro‐tert‐butanol‐hexamethylene diisocyanate is developed with highly hydroph

Piezoelectric nanogenerators (PENGs) and triboelectric nanogenerators (TENGs) are representative technologies that can harvest mechanical energy. In general, piezoelectric/triboelectric hybrid generators can harvest considerable energy with a limited input; however, PENGs and TENGs entail different requirements for harvesting energy. Specifically, PENGs produce a large output when a large mechanical strain is applied, and TENGs require a large surface area to produce a high power. Therefore, it

Currently, wind energy harvesting is in the limelight. However, with the existing electromagnetic wind generators, it is difficult to harvest multifariously-wasted breezes. To harvest energy from winds at a wide range of speeds, wind-driven triboelectric nanogenerators (TENGs) are studied. However, a critical limitation of general wind-driven TENGs is that their power output is low. Therefore, an innovative strategy is necessary to generate high output power even from breeze. Herein, an approach

The triboelectric nanogenerator (TENG) is a recent mechanical energy harvesting technology that has been attracting significant attention. Its working principle involves the combination of triboelectrification and electrostatic induction. The TENG can harvest electrical energy from both solid-solid and liquid-solid contact TENGs. Due to their physical difference, triboelectric materials in the solid-solid TENG need to have high mechanical properties and the surface of the liquid-solid contact TE

Energy harvesting is a method of converting energy from ambient environment into useful electrical energy. Due to the increasing number of sensors and personal electronics, energy harvesting technologies from various sources are gaining attention. Among energy-harvesting technologies, triboelectric nanogenerator (TENG) was introduced as a device that can effectively generate electricity from mechanical motions by contact-electrification. Particularly, liquid-solid contact TENGs, which use the li

With the rise of portable and wearable electronics, a fast-charging, long-lasting power solution is needed; thus, there are attempts to harvest energy from the ambient environment. Mechanical energy harvesting through piezoelectric and triboelectric nanogenerators (PENG and TENG) is a promising approach due to their light weight, low cost, and high-power density in comparison to other technologies. Both types of generators are capable of charging portable and smart devices on their own by conver