The swelling ratio of a network polydimethylsiloxane correlates with the Hansen solubility parameters, δd, δp and δh and the vapour pressures of organic vapours. The use of PDMS as a mechanical actuator in a prototype wireless RFID passive sensor is demonstrated.

This letter introduces a novel dual band antenna for wearable WLAN computing applications. This antenna comprises 3 discs and a coaxial post. Its appearance is of a standard metal button of the type used in denim jeans. The antenna is easily disguised and is less sensitive to clothing than printed patches which use the textile fabric as a substrate or superstrate. The antenna requires no external matching circuitry and operates at 2400MHz and 5200MHz. The radiation patterns are omni-directional around the central post of the antenna.

This paper presents a broadband frequency tunable and polarization reconfigurable circularly polarized (CP) antenna, using a novel active electromagnetic band gap (EBG) structure. The EBG surface employs identical metallic rectangular patch arrays on both sides of a thin substrate, but rotated by 90 from each other. The active bias circuits are also orthogonal for each surface, enabling the reflection phases for orthogonal incident waves to be tuned independently in a wide frequency range. By placing a wideband coplanar waveguide (CPW) fed monopole antenna above the EBG surface, and properly tuning the bias voltages across the varactors in each direction, CP waves can be generated at any desired frequency over a broad band. In accordance with simulations, the measured 3 dB axial ratio (AR) bandwidth reaches 40% (1.03-1.54 GHz), with good input matching and radiation patterns at six presented sampling frequencies. The polarization reconfigurability is verified by simulations and measurements, and shown to be capable of switching between left hand circular polarization (LHCP) and right hand circular polarization (RHCP).

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The present work describes the inkjet printing and low temperature sintering of silver nanoparticle inks onto transfer tattoo paper. Our approach results in silver features of excellent resolution and conductivity and, subsequently the first passive UHF RFID transfer tattoo tags functional mounted on human skin of improved performance when compared to screen printed passive UHF RFID transfer tattoo paper tags.Moreover, inkjet printed passive UHF RFID transfer tattoo tags show similar performance to copper etched passive UHF RFID tags on plastic substrates. This study compares the image quality (resolution) and electrical performance of two commercial silver nanoparticle inks inkjet printed on transfer tattoo paper.The optimal printing and sintering parameters to obtain high resolution features of resistivities 20 to 57 times the resistivity of bulk silver (1.59 Â 10 À6 ohm cm) are described. We demonstrate how, by selectively depositing ink in specific areas of the antenna, read distance of passive UHF RFID tags can be increased from 54 to 68 cm whilst decreasing the amount of ink used by 33%. Furthermore, this approach results in inkjet printed passive UHF RFID tattoo tags with larger read distance than silver screen printed passive UHF RFID tattoo tags, 45 cm, and similar to copper etched passive UHF RFID plastic tags, 75 cm. Moreover, inkjet printed passive UHF RFID tattoo tags in this work are considerably thinner (1-5 mm) than screen and etched passive UHF RFID tags (tens of micrometers) hence, making the former more appealing to the end user. In addition to this, inkjet printing is compatible with large area manufacturing techniques and has the potential to evolve as one of the most promising RFID mass-production techniques. Therefore, this work represents a step towards the commercialization of on-body transfer tattoo paper passive UHF RFID tags.

Interdependence between ink, substrate and sintering method on inkjet printed devices.

Abstract-Accurate and precise motion tracking of limbs and human subjects has technological importance in various healthcare applications. The use of Impulse Radio Ultra Wideband (UWB) technology due its inherent properties is of recent interest for high accuracy localisation. This paper presents experimental investigations and analysis of indoor human body localisation and tracking of limb movements in 3D based on IR-UWB technology using compact and cost-effective body worn antennas. The body-centric wireless channel characterisation has been analysed in detail using parameters such as path loss magnitude, number of multipath components, RMS delay spread, signal amplitude and Kurtosis with the main focus to differentiate between line-of-sight (LOS) and non-line-of-sight (NLOS) situations. Fidelity of the received signal is also calculated for different activities and antenna positions to study the pulse preserving nature of the UWB antenna when it is placed on the human body. The results reported in this paper have high localisation accuracy with 90 % in the range of 0.5 to 2.5 cm using simple and cost-effective techniques which is comparable to the results obtained by the standard optical motion capture system.