Textile-Based Inkjet-Printed RFIDs: Exploring wearable antennas in the real world

Growing demand in the wearable device industry for noninvasive, user-connected, and real-time activity trackers and body monitors is increasing the need for low-profile wearable antennas on fabric substrates, particularly for health and safety applications. Current data regarding environmental and human factors in this field that affect the real-world use of the devised antennas are incomplete. This article presents data regarding the impact of garment position, especially the distance between the skin and fabric substrate, on antenna performance. A distance of the substrate from the skin in the less than a 5-mm range was found to have a significant influence on antenna performance. The effects of humidity and dampness on the permittivity of five types of fabrics commonly used in commercial and health care-related garments are also investigated. The performance of a textile-based RFID printed directly on a nonconductive interface layer situated on single jersey knit cotton fabric was studied, and sheet resistance results of inkjet printing with two conductive nanoparticle inks from NovaCentrix are presented.