Fully-Textile, Wearable Chipless Tags for Identification and Tracking Applications

In this work, two fully-textile wearable devices, to be used as chipless identification tags in identification and tracking applications are presented. For the fabrication of the fully-textile tags, a layer of fleece was used as a substrate, while an adhesive non-woven conductive fabric was employed for the conductive parts. To allow radio-frequency identification of these chipless tags, two alternative techniques were used. One relies on associating a binary code with the resonance frequency of resonant devices: the presence/absence of the resonance peaks in the transmission scattering parameter, | S 21 | , of a set of resonators is used to encode a string of bits. The second technique for accomplishing radio-frequency identification of the chipless tags resorts to a frequency-shift coding technique, which is implemented by modifying the configuration of a hairpin resonator. The obtained numerical and experimental results confirm the suitability of the proposed strategies for obtaining entirely-textile, wearable chipless tags for identification and tracking purposes, which can be particularly useful, especially in the industrial sector. In this field, in fact, the proposed solutions would guarantee a seamless integration with clothes and would facilitate the user’s interaction with the IoT infrastructure. In this regard, one of the envisaged application scenarios related to the tracking of hides in the leather industry is also presented.

A miniaturized hairpin resonator for the high selectivity of WLAN bandwidth

In this article, a miniaturized hairpin resonator has been presented to introduce the high selectivity of Wireless Local Area Network (WLAN) bandwidth. In the construction of the hairpin resonator, short-circuited comb-lines are electrically coupled with the two longer edges of a rectangular-shaped loop. The hairpin resonator has been designed and fabricated with the Taconic TLX-8 substrate with a center-frequency at 2.45 GHz. The resonator exhibits a second order quasi-Chebyshev bandpass response. A low insertion loss has been found as -0.36 dB with a minimum return loss as -36.71 dB. The filtering dimension of this hairpin resonator occupies a small area of 166.82 mm2. This hairpin resonator is highly selective for the bandpass applications of the entire WLAN bandwidth.