Electromagnetic Metamaterials: Transmission Line Theory and Microwave Applications. By Christophe Caloz and Tatsuo Itoh.

The theoretical study of a 3D photonic topological metacrystal based on an all-dielectric metamaterial platform shows robust propagation of surface states along 2D domain walls, making it a promising solution for photonics applications. The proposed metacrystal design might also open the way for the observation of elusive fundamental physical phenomena.

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Three-Dimensional All-Dielectric Photonic Topological Insulator

Energy harvesting technology may be considered an ultimate solution to replace batteries and provide a long-term power supply for wireless sensor networks. Looking back into its research history, individual energy harvesters for the conversion of single energy sources into electricity are developed first, followed by hybrid counterparts designed for use with multiple energy sources. Very recently, the concept of a truly multisource energy harvester built from only a single piece of material as the energy conversion component is proposed. This review, from the aspect of materials and device configurations, explains in detail a wide scope to give an overview of energy harvesting research. It covers single-source devices including solar, thermal, kinetic and other types of energy harvesters, hybrid energy harvesting configurations for both single and multiple energy sources and single material, and multisource energy harvesters. It also includes the energy conversion principles of photovoltaic, electromagnetic, piezoelectric, triboelectric, electrostatic, electrostrictive, thermoelectric, pyroelectric, magnetostrictive, and dielectric devices. This is one of the most comprehensive reviews conducted to date, focusing on the entire energy harvesting research scene and providing a guide to seeking deeper and more specific research references and resources from every corner of the scientific community.

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Energy Harvesting Research: The Road from Single Source to Multisource.

Wearable antennas have gained much attention in recent years due to their attractive features and possibilities in enabling lightweight, flexible, low cost, and portable wireless communication and sensing. Such antennas need to be conformal when used on different parts of the human body, thus need to be implemented using flexible materials and designed in a low profile structure. Ultimately, these antennas need to be capable of operating with minimum degradation in proximity to the human body. Such requirements render the design of wearable antennas challenging, especially when considering aspects such as their size compactness, effects of structural deformation and coupling to the body, and fabrication complexity and accuracy. Despite slight variations in severity according to applications, most of these issues exist in the context of body-worn implementation. This review aims to present different challenges and issues in designing wearable antennas, their material selection, and fabrication techniques. More importantly, recent innovative methods in back radiations reduction techniques, circular polarization (CP) generation methods, dual polarization techniques, and providing additional robustness against environmental effects are first presented. This is followed by a discussion of innovative features and their respective methods in alleviating these issues recently proposed by the scientific community researching in this field.

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Wearable Antennas: A Review of Materials, Structures, and Innovative Features for Autonomous Communication and Sensing

Critical review on hazardous pollutants in water environment: Occurrence, monitoring, fate, removal technologies and risk assessment.

Direct laser fabrication of five-band symmetric terahertz metamaterial with Fano resonance

Wearable textile pressure sensors with piezoelectric properties are a very effective way of detecting movements of the human body based on the force exerted by the sensor. Owing to the merits of flexibility and breathability, the textile pressure sensor finds potential application in biomedical monitoring and human-machine interaction. The textile pressure sensor works on the principle of piezoelectricity where an electrode of conductive woven fabric forms the outer layer and a semi-conductive material such as ZnO is sandwiched between two conductive layers. ZnO is prepared using a simple hydrothermal method and SEM, XRD are two effective methods to detect the presence of ZnO on the conductive fabric. The pressure applied on the fabric is translated into voltage and the output voltages are compared using two samples of ZnO nanostructures. The effect of the seed layer is investigated under identical growth and measurement which influences the output performance of voltage. This property can be used to change the sensitivity and working range of pressure sensor for specific applications. The pressure sensor designed can be sewn directly onto the clothing which conforms to the human body’s flexible curved surface.

Zinc oxide nanostructure-based textile pressure sensor for wearable applications

In the present work, zinc oxide (ZnO) nanoparticles (NPs) were prepared using chemical co-precipitation technique. The prepared ZnO NPs were subjected to get modified directly using cellulose acetate (CA) which one of the important esters of cellulose. The possible application of CA functionalized ZnO nanocomposite (NC) has not been realized much in fabrication of electrochemical sensors. The as-prepared pure ZnO and CA functionalized ZnO NC were investigated using various analytical methods. The crystalline size was reduced due to the surface functionalization of CA on ZnO which was observed in XRD. With CA functionalization on ZnO, it was observed to be hexagonal rod shaped with reduced agglomeration in SEM images. The NC formation was further affirmed by IR analysis. The obtained material was employed as electrochemical sensor and was evaluated towards cadmium sensing property using cyclic voltammetry. In order to evaluate limit of detection (LOD) and sensitivity, square wave voltammetry was performed and showed that, under optimized conditions with linear detectable concentration range of 0.1–0.5 μM (R2 = 0.9937) LOD of 0.41 µM with significant sensitivity up to 3.11 μA/(μM). Based on the obtained results, NC was subjected to stability analysis and implemented on real time water samples.

A Facile Synthesis of Cellulose Acetate Functionalized Zinc Oxide Nanocomposite for Electrochemical Sensing of Cadmium ions

In this work, we developed a morphology involved cerium oxide/graphene oxide hybrid (CeO2/GO hybrid) nanocomposite based system using the ultrasonic method. X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM) have been performed to analyse the developed nanocomposite. The crystallite size of the hybrid was found to be 3.86 nm comparably lower than that of pure CeO2 (7.4 nm) which was confirmed by X-Ray diffraction analysis. The presence of functional groups was affirmed using FTIR analysis. The morphological features of pure CeO2 and hybrid were verified using FESEM. FESEM images reveals that, pure CeO2 nanoparticles are highly agglomerated and CeO2/GO hybrid possess nano-rectangular morphology. In addition, the developed hybrid system has been analysed to evaluate its scavenging anti-cancer potential against HeLa cell lines at various concentrations and incubation intervals using antiproliferative assay test. The test results reveals that, as the concentration of hybrid nanocomposite increases the cell death also increases. Here, “IC50” refers to lowest concentration of sample (CeO2/GO hybrid) at which nearing 50% of HeLa cells remains alive and rest of the cells remains dead. In our study, 31.2 µg/ml is considered to be IC50 value for which nearing 50% of cells remains dead and it has been attained at an incubation period of 72 h. An dual acridine orange/ethidium bromide (AO/EB) fluorescent staining, was performed at two specific concentrations (i.e.) 125 µg/ml and 1000 µg/ml of developed hybrid nanocomposite to identify apoptosis-associated changes of cell membranes during the process of apoptosis. Change in color for both live cells (green) and dead cells (red) were viewed using fluorescence microscopy. The quantitative analysis was done using flow cytometry (FACS study) to investigate the cell cycle at which maximum number of HeLa cells has been killed due to interaction with developed CeO2/GO hybrid. The FACS study test results reveals that, maximum cancer cells were arrested at R3 (G2/M) phase. Hence, the developed CeO2/GO hybrid has shown improved anticancer efficacy against HeLa cell line and thus it acts as a better therapeutic agent for cervical cancer diagnosis.

Ultrasonic Assisted Cerium Oxide/Graphene Oxide Hybrid: Preparation, Anti-proliferative, Apoptotic Induction and G2/M Cell Cycle Arrest in HeLa Cell Lines

A compact Ultra Wide Band (UWB) Multiple Input Multiple Output (MIMO) monopole antenna is presented in this paper. It consists of two identical semi-circular radiators with symmetrical stepped elliptical structure. In order to enhance the bandwidth, curved-I shaped defective ground is introduced in the ground plane. The proposed MIMO antenna accomplish a compact size of 0.333 λ 0 X 0.233 λ 0 (λ 0 is the wavelength at first lower frequency) and features a UWB ranges from 1.99 -10.02 GHz with a fractional bandwidth of 133.7 % covering Wi-Fi, Wi-MAX and WLAN applications. The inter-element edge-to-edge spacing between the antenna elements is 8.6 mm. It provides a good isolation of better than 13 dB over 1.99 GHz-4.5 GHz and 22.5 dB over 4.5 GHz -10.02 GHz without any additional isolating elements. The minimum correlation achieved in this proposed UWB MIMO antenna is < 0.0036. The proposed antenna offers a good diversity performance. Moreover, it offers a peak gain of 8.18 dB and maximum radiation efficiency of 99.8 % and the stable radiating fields are radiates in nearly omni direction.

B. S. Sreeja

Papers

Direct laser fabrication of five-band symmetric terahertz metamaterial with Fano resonance

Zinc oxide nanostructure-based textile pressure sensor for wearable applications

A Facile Synthesis of Cellulose Acetate Functionalized Zinc Oxide Nanocomposite for Electrochemical Sensing of Cadmium ions

Ultrasonic Assisted Cerium Oxide/Graphene Oxide Hybrid: Preparation, Anti-proliferative, Apoptotic Induction and G2/M Cell Cycle Arrest in HeLa Cell Lines

A compat UWB MIMO antenna with high isolation and low correlation for wireless applications