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The present work has been carried out to evaluate the dielectric properties and ac-electrical conductivity of cellulose nanofibers. The cellulose nanofibers (CNF) described in this work are the ones extracted from cotton via a simple acid hydrolysis method and are characterized with X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and UV-Visible diffuse reflectance spectroscopy. The optical band gap of CNF found out using the Kubelka-Munk plot is 3.30 eV. The dielectric constant, dielectric loss, and ac-electrical conductivity of the prepared CNF have been investigated in the temperature range from 30 °C to 300 °C and in the frequency range from 50 Hz to 5 MHz. The synthesized system exhibits a higher dielectric constant value for all temperatures in the low-frequency (0.1 kHz) region and a frequency-independent behavior above 10 kHz. In the high-frequency region, the dielectric constant is independent of temperature. Also, the study shows that the conductivity increases with increasing frequency and temperature. The maximum values of ac-conductivity at room temperature (30 °C) and high temperature (300 °C) are found to be 4.58 9 10 -5 S/cm and 2.26 9 10 -4 S/cm, respectively. In brief, the studies point to the application potential of CNF for future flexible electronics.

The rising demand for ultra low power devices is the result of the desperate urge of man to conserve energy while continuing to enjoy the benefits of modern technology. Consistent and efficient sourcing of these devices is a test. RF energy harvesting systems are emerging as an efficient solution to this exigent situation since it harvests the otherwise wasted ambient energy. This paper presents an overview of such systems with reference to their design configurations, possible sources, applications and the current scenario in India.

Nano cellulose is a material of current interest that has attracted considerable attention from researchers due to its interesting properties such as low toxicity, availability, natural abundance, biodegradability, and flexible surface chemistry. Cellulose fiber, usually derived from wood, plant walls or cotton is an eco-friendly thermal insulation material. The cellulose nanofibers (CNFs) described in this work were derived from cotton via sulfuric acid hydrolysis followed by ultrasonication. The formation of CNF and its morphology were analyzed using Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The thermooptic parameters of the prepared sample, which to the author's knowledge has not been reported so far, were studied by the dual beam mode-matched thermal lens technique. Thermal diffusivity (2.61 × 10 −8 m 2 /s) and thermal conductivity (0.108 W/mK) values of the prepared CNFs clearly point to the application potential of the material.

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