High-aspect ratio β-Ga₂O₃ nanorods consisting of prism-like crystals were formed using gallium oxyhydroxide and ammonia hydroxide via a hydrothermal synthesis followed by the subsequent calcination process. The formation of high-aspect ratio β-Ga₂O₃ nanorods was attributed to the oriented attachment mechanism that was present during the hydrothermal synthesis. A field-effect transistor was fabricated using the high-aspect ratio β-Ga₂O₃ nanorod, and it exhibited the typical charge transfer properties of an n-type semiconductor. This facile approach to forming high-aspect ratio nanorods without any surfactants or additives can broaden the science of β-Ga₂O₃ and expedite the integration of one-dimensional β-Ga₂O₃ into future electronics, sensors, and optoelectronics.

Cylindrical silk fiber (SF) was coated with Graphene oxide (GO) for capacitive humidity sensor applications. Negatively charged GO in the solution was attracted to the positively charged SF surface via electrostatic force without any help from adhesive intermediates. The magnitude of the positively charged SF surface was controlled through the static electricity charges created on the SF surface. The GO coating ability on the SF improved as the SF’s positive charge increased. The GO-coated SFs at various conditions were characterized using an optical microscope, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy, and LCR meter. Unlike the intact SF, the GO-coated SF showed clear response-recovery behavior and well-behaved repeatability when it was exposed to 20% relative humidity (RH) and 90% RH alternatively in a capacitive mode. This approach allows humidity sensors to take advantage of GO’s excellent sensing properties and SF’s flexibility, expediting the production of flexible, low power consumption devices at relatively low costs.

In this study, we report on the electrochemical properties of a solid state lithium ion battery (LIB) using a poly (ethylene glycol) dimethyl ether (PEGDME)-based solid polymer electrolyte (P-SPE). The LIB is prepared using a LiFePO₄ (LFP) cathode and graphite anode material with P-SPE, and the kinetic properties of the lithium ions in the P-SPE are investigated. The synthesized P-SPE is shown to be suitable solid polymer electrolyte candidate for LIB applications. LFP and graphite are selected as electrode materials to validate their effectiveness in different battery cells with respect to their high energy density and inherent safety. The five-layer stacked 5 × 6 cm² pouch-type LIB demonstrates a high capacity of 90 mAh (0.6 mAh/cm²) or more in the initial cycle, and it shows cycle stability with a capacity decrease of 20% over 500 cycles. We test the manufactured pouch-type full cells under extreme conditions (e. g., cutting, crushing and exposure of the battery cell to the atmosphere). LIBs using the developed P-SPE are promising solid polymer electrolyte candidates for wearable LIB as well as high energy LIB applications.