Hyun‐Cheol Song

Recent advances in lithography technology and the spread of 3D printers allow us a facile fabrication of special materials with complicated microstructures. The materials are called "designed materials" or "architectured materials" and provide new opportunities for material development. These materials, which owing to their rationally designed architectures exhibit unusual properties at the micro- and nano-scales, are being widely exploited in the development of modern materials with customized

We demonstrate a microscale vibration energy harvester exhibiting an ultra-low resonance frequency and high power density. A spiral shaped microelectromechanical system (MEMS) energy harvester was designed to harvest ambient vibrations at a low frequency (<;200 Hz) and acceleration (<;0.25 g). High quality Pb(Zr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.48</sub> Ti <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w

Piezoelectric energy harvesters (PEHs) aim to generate sufficient power to operate targeting device from the limited ambient energy. PEH includes mechanical-to-mechanical, mechanical-to-electrical, and electrical-to-electrical energy conversions, which are related to PEH structures, materials, and circuits, respectively; these should be efficient for increasing the total power. This critical review focuses on PEH structures and materials associated with the two major energy conversions to improv

(1− x )(Na 0.5 K 0.5 )NbO 3 – x LiNbO 3 [(1− x )NKN– x LN] ceramics were produced by the conventional solid‐state sintering method, and their microstructure and piezoelectric properties were investigated. The formation of the liquid phase and K 6 Li 4 Nb 10 O 30 second phase that were observed in the (1− x )NKN– x LN ceramics was explained by the evaporation of Na 2 O during the sintering. A morphotropic phase boundary (MPB) was observed in the specimens with 0.05&lt; x &lt;0.08. Promising piezo

Acoustic energy transfer using ferroelectrically augmented triboelectric receivers can efficiently deliver energy to implantable medical devices, marine cable operation sensors, and electronic devices with electromagnetic interference shielding cases.

Abstract Despite the rapid development of various wearable generators to harvest energy from human activity, they are limited to single or intermittent power generation. Here, stretchable and washable energy harvesting fabric is reported, which enables biomechanical and biochemical generation through co‐weaving triboelectric generator (TEG) and perspiration electric generator (PEG)‐based fibers. The two energy harvesting approaches can work individually or simultaneously, thereby combating humid

Piezoelectric materials are a class of materials that can generate an electric charge when subjected to mechanical stress, or vice versa. These materials have a wide range of applications, from sensors and actuators to energy-harvesting devices and medical implants. Recently, there has been growing interest in using 3D printing to fabricate piezoelectric materials with complex geometries and tailored properties. Three-dimensional printing allows for the precise control of the material’s composit

An innovative autonomous resonance-tuning (ART) energy harvester is reported that utilizes adaptive clamping systems driven by intrinsic mechanical mechanisms without outsourcing additional energy. The adaptive clamping system modulates the natural frequency of the harvester's main beam (MB) by adjusting the clamping position of the MB. The pulling force induced by the resonance vibration of the tuning beam (TB) provides the driving force for operating the adaptive clamp. The ART mechanism is po

Abstract Multilayer ceramic capacitors (MLCC) are widely used in consumer electronics. Here, we provide a transformative method for achieving high dielectric response and tunability over a wide temperature range through design of compositionally graded multilayer (CGML) architecture. Compositionally graded MLCCs were found to exhibit enhanced dielectric tunability (70%) along with small dielectric losses (&lt;2.5%) over the required temperature ranges specified in the standard industrial classif