Inkjet printing of metal nanoparticles for green UHF RFID tags

UHF RFID tags are nowadays widely and successfully implemented in many distinct applications, but unfortunately the traditional production process and incorrect disposal of such devices have a negative impact on the environment. In this work silver and gold nanoparticle inks were printed by a consumer inkjet printer on eco-friendly substrates like paper and PET in order to make the manufacturing process less harmful to the ecosystem. A dipole antenna with matching loop was designed for the RFID chip EM4325 from EM Microelectronics, which has an integrated temperature sensor, at the frequency of 866 MHz. Based on this design, simulations of the greener tags are presented and compared as a proof of concept, without optimizing the designs at first for the different materials. The printings with silver (unlike the gold) were conductive with self-sintering. IPL sintering was conducted to reduce the sheet resistance from the silver ink and to turn the gold ink conductive. First S11 parameter and read distance measurements are shown as well as the simulations with the optimized antenna designs.