Graphene-based soft wearable antennas

Electronic textiles (e-textiles) are about to face tremendous environmental and resource challenges due to the complexity of sorting, the risk to supplies and metal contamination in textile recycling streams. This is because e-textiles are heavily based on the integration of valuable metals, including gold, silver and copper. In the context of exploring sustainable materials in e-textiles, we tested the boundaries of chemical vapour deposition (CVD) grown multi-layer (ML) graphene in wearable communication applications, in which metal assemblies are leading the way in wearable communication. This study attempts to create a soft, textile-based communication interface that does not disrupt tactile comfort and conformity by introducing ML graphene sheets. The antenna design proposed is based on a multidisciplinary approach that merges electromagnetic engineering and material science and integrates graphene, a long-lasting alternative to metal components. The designed antenna covers a wide bandwidth ranging from 3 GHz to 9 GHz, which is a promising solution for a high data rate and efficient communication link. We also described the effects of bending and proximity to the human body on the antenna's overall performance. Overall, the results suggested that graphene-based soft antennas are a viable solution for a fully integrated textile-based communication interface that can replace the current rigid, restrictive and toxic approaches, leading to a future where eco-friendliness and sustainability is the only way forward

Graphene-enabled adaptive infrared textiles

Interactive clothing requires sensing and display functionalities to be embedded on textiles. Despite the significant progress of electronic textiles, the integration of optoelectronic materials on fabrics remains as an outstanding challenge. In this Letter, using the electro-optical tunability of graphene, we report adaptive optical textiles with electrically controlled reflectivity and emissivity covering the infrared and near-infrared wavelengths. We achieve electro-optical modulation by reversible intercalation of ions into graphene layers laminated on fabrics. We demonstrate a new class of infrared textile devices including display, yarn, and stretchable devices using natural and synthetic textiles. To show the promise of our approach, we fabricated an active device directly onto a t-shirt, which enables long-wavelength infrared communication via modulation of the thermal radiation from the human body. The results presented here provide complementary technologies which could leverage the ubiquitous use of functional textiles

Effects of bolt torque and contact resistance on the performance of the polymer electrolyte membrane electrolyzers

WOS: 000350930600014The effect of bolt torque and contact resistance on the performance of Proton Exchange Membrane (PEM) Electrolyzers are investigated by a 50 cm(2) cell. The cell is designed and manufactured in house. The performance and contact resistance of the cell with three different gasket materials for demanding bolt torques are measured. The pressure distribution inside the cell is obtained by using pressure sensitive films. The pressure acting on the membrane electrode assembly (MEA) is calculated by analyzing and quantifying intensities of pressure film images. 3D plots of pressure distribution for predefined bolt torque values are obtained to understand the pressure distribution over the active area. The performance of the cell is enhanced when bolt torque is increased. However, beyond a value, relatively weak cell components such as diffusion layers are damaged and performance loss is observed due to the mass transfer limitations. The best efficiency is reached at 15 Nm bolt torque for Polytetrafiuoroethylene (PTFE) and Ethylene Propylene Diene Monomer (EPDM) gaskets. For silicon gasket best efficiency is reached at 15 Nm at lower current densities and at 10 Nm at higher current densities. Increasing clamping pressure is found to be developing more contact points between the interfaces and results in decrease in contact resistance inside the cell. (C) 2015 Elsevier B.V. All rights reserved.Research Projects Unit of Nigde University [FEB2013/23]The authors would like to thank the Research Projects Unit of Nigde University for the financial support under the contract number of FEB2013/23

Video-speed Graphene Modulator Arrays for Terahertz Imaging Applications

Electrically tuneable high mobility charges on graphene yield an efficient electro-optical platform to control and manipulate terahertz (THz) waves. Real-world applications require a multiplex THz device with efficient modulation over a large active area. The trade-off between the efficient gating and switching speed, however, hinders the realization of these applications. Here, we demonstrate a large-format 256-pixel THz modulator which provides high-frame-rate reconfigurable transmission patterns. The time-domain and frequency-domain THz characterizations of graphene devices reveal the relaxation pathways of gate-induced charges and ion packing at graphene-electrolyte interface. The fundamental understanding of these limiting factors enables us to break the trade-off permitting switching frequencies up to 1 kHz. To show the promises of these devices, we demonstrate a single-pixel THz camera which allows spatial and spectroscopic imaging of large-area objects without any moving components. These results provide a significant advancement towards the achievement of non-invasive THz imaging systems using graphene-based platforms.Comment: 16 pages, 5 figure

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Phase reconstruction of an oscillating dielectric disc pendulum, recorded using off-axis holography at 290 GHz. Frames captured at 103 fps = Exp0. !May contain flashing patterns

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Phase reconstruction of an oscillating dielectric disc pendulum, recorded using off-axis holography at 290 GHz. Frames captured at 72 fps = Exp1. !May contain flashing patterns

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Phase reconstruction of an oscillating dielectric disc pendulum, recorded using off-axis holography at 290 GHz. Frames captured at 43 fps = Exp2. !May contain flashing patterns