Protecting Wearable UHF RFID Tags With Electro-Textile Antennas: The challenge of machine washability

Ultrahigh frequency radio-frequency identification (UHF RFID) tags have shown enormous potential in wearable applications for sensing human vital signs. However, the integration of UHF RFID tags in clothing to achieve machine washability remains a challenge. In this study, we investigated different ways of protecting wearable UHF RFID tags with electro-textile antennas against repeated washing. We replaced the antennas of commercial UHF RFID tags with the antennas made from a silver-coated fabric. Twenty-three types of methods, including five integrated circuit (IC)-protection methods and seven fixation/cover methods, were compared, with each having ten identical samples. The 230 samples underwent 20 cycles of machine washing and drying, and the changes in received signal strength indicator (RSSI) and the number of failed tags after washing were recorded and analyzed statistically. We found that 1) water penetration does not have a negative impact on tag functionality, therefore, being waterproof is not a requirement for the coating material; 2) heat-bond hem taping is the most efficient IC protection method; 3) heat and high pressure is effective to improve tag endurance; and 4) fusible interlinings and ironing, used in traditional garment production, can be effective.