Takaaki Kasuga

A nanopaper sensor device that combines humidity sensing, wireless information transmission, and degradability has been fabricated using wood-derived nanopaper as the substrate and dielectric layers. The nanopaper shows excellent suitability for capacitor dielectric layers because of its high dielectric constant, insulating properties suitable for thin-film formation, and lamination properties. A wireless transmission circuit containing the nanopaper capacitor can transmit radio signals in the m

Nanopaper prepared from holocellulose pulp is one of the best substrates for flexible electronics because of its high thermal resistance and high clear transparency. However, the clearness of nanopaper decreases with increasing concentration of the starting cellulose nanofiber dispersion-with the use of a 2.2 wt % dispersion, for example-resulting in translucent nanopaper with a high haze of 44%. To overcome this problem, we show that the dilution of this high-concentration dispersion with water

The orientation control and the formation of hierarchical structures of nanoscale components, such as bionanofibers and nanosheets, have attracted considerable research interest with the aim of achieving sophisticated functional materials. Herein, we report a simple and flexible strategy for constructing sophisticated hierarchical structures through electrophoretic and electrochemical deposition. Cellulose nanofibers (CNFs), which are used as model materials, are deposited on an anode in an aque

Abstract Sensor networks comprising small wireless sensor devices facilitate the collection of environmental information and increase the efficiency of outdoor practices, including agriculture. However, the sensor‐device installation density of a network is limited because conventional sensor devices must be removed after use. In this study, a sustainable dense sensing system that combines simplified degradable sensor devices, wireless power supply, and thermal‐camera image‐based information rec

Water is detrimental to electronic devices because it easily causes short circuits. The use of sealing to prevent water permeation is considered as the current conventional solution; however, the trend for developing flexible and stretchable electronic circuits has placed severe demands on waterproof technologies. This report describes a coating that protects circuits and prevents between-wire short circuits, even if the waterproof seals are damaged and the circuit becomes wet. We show that when

Dehydration of a cellulose nanofiber (CNF)/water dispersion requires large amounts of energy and time due to the high hydrophilicities and high specific surface areas of the CNFs. Various dehydration methods have been proposed for CNF/water dispersions; however, an efficient dehydration method for individually dispersed CNFs is needed. Here, electrodeposition of CNFs was evaluated as a dehydration method. Electrodeposition at a DC voltage of 10 V on a 0.2 wt% CNF/water dispersion resulted in a c

Efficient dehydration of cellulose nanofiber (CNF)/water dispersions and hydrogels is still a challenge in the industrial use of CNFs. In this study, electroosmosis of CNF hydrogels was evaluated as a dehydration method. TEMPO-oxidized CNF hydrogels were rapidly dehydrated by applying DC 20 V, and the CNF concentration increased from 0.5 wt% to ∼10 wt% within 3 min. The energy efficiency of dehydration was more than 7 times greater than that of evaporation, and the resulting concentrated CNF hyd

The spatial distribution of the electric field in the low to high frequency bands radiated from printed circuit board (PCB) should be estimated continuously from near to far field. The characteristic of the electric field distribution is analyzed by the FDTD-multiple analysis space (FDTD-MAS) method, which can analyze from near to far field continuously, and compared with measured results. Since the analyzed electric field distribution is good agreement with measured results, it is suggested tha

ABSTRACT Transparent wood and translucent wood are attracting attention as promising sustainable optical materials. Typically, translucent wood is prepared through chemical treatments (bleaching, etc.); thus, there is a need for more ecofriendly, sustainable preparation methods. In this study, translucent wood was prepared by precisely controlling the compression conditions. Natural wood was densified to reduce internal voids that cause light scattering, resulting in a light transmittance of mor

As the basic study of the electromagnetic interference (EMI) problem at the circuit elements, the near magnetic field distributions above resistors for the termination of a transmission line are measured to reveal the profile of radiation. Five kinds of resistors and two types of resistance values are sampled. The results showed that the variation of the near magnetic field distribution above the transmission line is effected largely by the reactance of the resistor at the high frequency. These