A novel wireless oxygen gas sensor based on silver film loaded on a patch antenna

In this work, a patch antenna loaded with sensitive silver film was employed for the detection of oxygen gas at high concentrations. SEM micrographs demonstrate that the morphology of the Ag film presents an elevated degree of porosity, confirming that the film is suitable for adsorbing O2 gas molecules on its surface. Numerical simulation performed was validated, and the values of the far-field parameters showed that the investigated device works efficiently as an antenna. During the tests carried out, it was observed that the device responds sensitively to the presence of oxygen gas demonstrating shifts of the antenna resonant frequency to higher values as a function of the O2 concentration. The antenna sensitivity was calculated, presenting a value of 0.14 MHz/ O2% for the frequency at 5.968 GHz, 0.23 MHz/O2% for frequency at 8.246 GHz, and 0.15 MHz/O2% for the frequency at 10.039 GHz. Results obtained indicate that the patch antenna tested could be used as a sensor of oxygen gas in environments with elevated concentrations of this gas, such as oxygen concentrators and other medical equipment. Because the device analyzed is an antenna, it would be possible transmitting the sensing information to another device which would make it a potential candidate for application in healthcare monitoring.