Functionalization of high frequency SAW RFID devices for ozone dosimetry

In this paper we report new work on the gravimetric detection of ozone at EPA and OSHA relevant concentrations (approximately 100 ppb) in filtered ambient air. We have extended our proof-of-concept work which used both quartz crystal microbalance (QCM) and surface acoustic wave (SAW) resonators. We now enable detection using our high frequency SAW RFID devices. Such surface wave devices are extremely sensitive to the viscosity, thickness, and uniformity of the reactive or sorbent coating. We report laboratory characterization of our polymer-coated SAW sensors operating between 200 and 600 MHz on lithium niobate substrates. Return loss measurements confirm adequate load bearing even at 550 MHz. We compare both the temperature and ozone sensitivity of the RFID devices to conventional resonators. In conclusion, we suggest the design improvements to yield a next generation of SAW RFID ozone sensors with even greater sensitivity.