Abstract-A new ultrawideband (UWB) textile antenna designed for UWB wireless body area network (WBAN) applications is presented. Unlike previous textile antennas, these antennas offer a direct integration into clothing due to a very small thickness (0.5 mm) and flexibility. We have realized two different designs of textile antennas: coplanar waveguide fed printed UWB disc monopole and UWB annular slot antenna. To our knowledge, these are the first textile UWB antennas reported in the open literature. Measured return loss and radiation pattern characteristics of textile UWB antennas agree well with simulations. Moreover, measured transfer functions show that these textile antennas possess excellent transient characteristics, when operating in free space as well as on the human body. They can operate in the entire UWB band approved by the Federal Communications Commission (3.1-10.6 GHz).Index Terms-Body area networks, textile antennas, ultrawideband (UWB).

Abstract-This paper presents electromagnetic energy absorption in the homogeneous and layered human body models due to body-worn UWB antennas, at frequencies of 3, 6 and 8 GHz. Typical small planar UWB antennas are used in this study: printed UWB disc monopole and UWB slot antenna. Distances of 2, 5 and 10 mm (reactive near-field region) between antennas and human body were chosen, approximating realistic scenarios of operation in Wireless Body Area Networks. To approximate different parts of the human body, or body variations among different users, we compare results obtained for the planar homogeneous (muscle) model with those for three-layer body models (skin, fat and muscle), with different thicknesses of the skin (0.5-2 mm) and fat (1-9 mm) tissue. For these body models we investigate the electromagnetic energy absorption mechanism by examining the peak 1-g SAR and peak SAR (without mass averaging). Based on our results we present and discuss new finding concerning the general electromagnetic energy absorption mechanism in human tissues under reactive near-fields exposure conditions.

wileyonlinelibrary.comresorbable environmental monitors, disposable devices, hardware-secure digital memories, and other applications that are not well served by conventional technologies. [ 1 ] Such types of systems represent a subset of a broader class of a technology referred to as transient electronics. Early work [ 2 ] examined sequentially dissolvable electronics in which variations in the thicknesses and types of the constituent materials determine a time sequence for dissolution across the areas of integrated devices. An important recent advance [ 3 ] in this fi eld followed from the realization of on-demand, triggered dissolution via a remotely controlled microfl uidic system. In the present paper, we demonstrate that these platforms can be extended for use in multistaged transformations of functional behaviors in the transient electronics by means of programmed microfl uidic chemical etching at Electronic systems that enable programmable transformation of functional behaviors by remote control or by autonomous responses to user-defi ned circumstances create unusual engineering opportunities, where physical changes in the hardware induce desired changes in operation. This paper presents materials and device architectures for technologies of this type, in which localized microfl uidic chemical etching of targeted constituent components in the electronics occurs in a sequential, selective manner. Custom circuits that include reconfi gurable radio-powered thermal actuators with analog amplifi ers and square waveform generators illustrate the concepts.

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