Siyoung Lee

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 pressure.

Wearable auditory sensors are critical in user-friendly sound-recognition systems for smart human-machine interaction and the Internet of Things. However, previously reported wearable sensors have limited sound-sensing quality as a consequence of a poor frequency response and a narrow acoustic-pressure range. Here, a skin-attachable acoustic sensor is presented that has higher sensing accuracy in wider auditory field than human ears, with flat frequency response (15-10 000 Hz) and a good range o

Auditory sensors have shortcomings with respect to not only personalization with wearability and portability but also detecting a human voice clearly in a noisy environment or when a mask covers the mouth. In this work, an electret-powered and hole-patterned polymer diaphragm is exploited into a skin-attachable auditory sensor. The optimized charged electret diaphragm induces a voltage bias of >400 V against the counter electrode, which reduces the necessity of a bulky power source and enables t

Abstract Triboelectric nanogenerators (TENGs) have emerged as promising portable and sustainable energy sources in daily life, harvesting energy from human motion, water, and wind. However, they still face limitations in aspects such as contact area, deformability, wettability, and manufacturing method. Here, a wearable TENG incorporating an anisotropic domino structure based on a fluorinated elastomer blend is presented. Because of its thin, elongated structure with broad sides, the TENG achiev

Abstract Volatile organic compounds (VOCs) are utilized as essential biomarkers for plant health and the surrounding environmental conditions in light of global imperatives surrounding food security and sustainable agriculture. However, conventional VOC detection methods have inherent limitations related to operational costs, portability, in situ monitoring, and accessibility. Wearable electronic systems have garnered significant attention as an alternative method because of their capability to

Flexible and stretchable conductive thin films are required for the development of soft electronics; however, few existing films satisfy the requirements for both electrical/mechanical performances and process practicability. This study describes a simple approach to fabricate omnidirectionally and highly stretchable nanocracked metal thin films on thiolated elastomeric substrates by exploiting the eruption of a residual solvent contained in an elastomeric substrate during metal thermal evaporat

Monitoring crops' biotic and abiotic responses through sensors is crucial for conserving resources and maintaining crop production. Existing sensors often have technical limitations, measuring only specific parameters with limited reliability and spatial or temporal resolution. Wearable sensing systems are emerging as viable alternatives for plant health monitoring. These systems employ flexible materials attached to the plant body to detect nonchemical (mechanical and optical) and chemical para

Duplex nanoporous Cu was successfully fabricated by dealloying a dual-phase Mg???Cu precursor alloy consisting of intermetallic Mg2Cu and MgCu2. The duplex nanoporous Cu with embedded nanoporous struts exhibited highly enhanced strength compared to the typical monolithic nanoporous Cu under both compressive and flexural test conditions at room temperature; the duplex np-Cu sample exhibited a 12 times higher compressive strength and a 40 times greater flexural strength than the monolithic np-Cu s

Soft robotics has sought to emulate natural behaviors. One impressive ability of living systems is operating in confined and narrow pathways, from caterpillars to tapeworms. Among the soft actuators, dielectric elastomer actuators (DEAs) are suitable candidates for this ability with fully soft systems, energy, and power densities on par with natural muscles and simple electro-mechanical drive. In this letter, we present the systematic guideline for designing and fabricating a steerable tip based

Republic of Korea has unique geographical characteristics similar to those of an island, resulting in an isolated power system. For this reason, securing sufficient operating reserves for the system’s stability and reliability in the face of the intermittency of increasing variable renewable energy (VRE) is paramount, and this will pave the way to achieving the nation’s decarbonization target and carbon neutrality. However, the current reserve-operation method in Republic of Korea does not take

Titanium and Zircaloy-4 dissimilar alloys were brazed with a zirconium-titanium-copper-nickel amorphous filler alloy, and the resulting joint structures as well as their corrosion properties were examined. The microstructure of the brazed joints was investigated according to brazing holding time at 850 °C, and the corrosion property was analyzed by potentiodynamic polarization. During brazing, joints were produced by diffusion-induced isothermal solidification of the molten filler alloy. At a re

With the advent of human-machine interaction and the Internet of Things, wearable and flexible vibration sensors have been developed to detect human voices and surrounding vibrations transmitted to humans. However, previous wearable vibration sensors have limitations in the sensing performance, such as frequency response, linearity of sensitivity, and esthetics. In this study, a transparent and flexible vibration sensor was developed by incorporating organic/inorganic hybrid materials into ultra

Recently, electronic devices have been rapidly integrated in accordance with trends toward miniaturization, thinness, high performance, and multifunctionality. Consequently, the thermal management design within these devices has become critical in maintaining stable performance. Effective heat dissipation technologies, particularly, thermally conductive pastes and coating films, are essential for this purpose. Efficient heat transfer and dissipation in these coating pastes depend on the dispersi