This paper presents a planar monopole backed with a 2×1 array of Electromagnetic Band Gap (EBG) structures. The reflection phase of a single EBG unit cell has been studied and exploited towards efficient radiation of a planar monopole antenna, intended for wearable applications. The shape of the EBG unit cell and the gap between the ground and the EBG layer are adjusted so that the antenna operates at 2.45 GHz. The proposed antenna retains its impedance matching when placed directly upon a living human subject with an impedance bandwidth of 5%, while it exhibits a measured gain of 6.88 dBi. A novel equivalent array model is presented to qualitatively explain the reported radiation mechanism of the EBG-backed monopole. The proposed antenna is fabricated on a 68×38×1.57 mm 3 board of semi-flexible RT/duroid 5880 substrate. Detailed analysis and measurements are presented for various cases when the antenna is subjected to structural deformation and human body loading, and in all cases the EBG-backed monopole antenna retains its high performance. The reported efficient and robust radiation performance with very low specific absorption rate (SAR), the compact size, and the high gain, make the proposed antenna a superior candidate for most wearable applications used for offbody communication.

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This research is in line with an important comment from the first amputee who tried the prosthetic hand with tactile feedback developed within the Smarthand project [1]. While trying the system with tactile feedback the patient said: "It's a feeling I have not had in a long time. When I grab something tightly I can feel it in the fingertips. It's strange since I don't have them anymore! It's amazing." We describe here the instrumentation and methods for testing the abilities of humans to discriminate sensations generated by electrical stimulation applied to the skin on the forearm. The instruments allowed testing of electrical stimulation with various properties (pulse duration, intensity, and rate). We tested the perception and pain thresholds, with the emphasis that comfortable sensations are a must. During the tests subjects were asked to locate the point on the skin that was stimulated and describe their perception of the elicited sensation. Results of first tests with small concentric electrodes suggest that non-amputees can distinguish up to seven perceptual qualities (the most common one was vibration, followed by tingling and tickling). Certain sensations had a higher occurrence rate along one axial line of the forearm than another of the forearm. In terms of spatial acuity, the subjects had more difficulties in distinguishing between the positions in the axial direction of the forearm compared with the circumferential direction. These results guided the design of the new array electrode with multiple cathodes and anodes positioned circumferential to the forearm. The results of the tests conducted with this electrode design showed high location discernment accuracy, and demonstrated the ability to memorize and later accurately recall six different electrical “messages” created by delivering electrical stimulation onto three different electrode pads with two different stimulation parameters. [Projekat Ministarstva nauke Republike Srbije, br. TR35040

The low-dimensional-model-based electromagnetic imaging is an emerging member of the big family of computational imaging, by which the low-dimensional models of underlying signals are incorporated into both data acquisition systems and reconstruction algorithms for electromagnetic imaging, in order to improve the imaging performance and break the bottleneck of existing electromagnetic imaging methodologies. Over the past decade, we have witnessed profound impacts of the low-dimensional models on electromagnetic imaging. However, the low-dimensional-model-based electromagnetic imaging remains at its early stage, and many

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