This work is related to designing, fabricating, and testing a surface acoustic wave sensor to be used for detecting metastable inert gases, particularly helium. The assembly consists of two microsensor configurations: (a) a reference device with no deposition at the delay line and (b) a sensing device with an Au-activated TiO2 e-beam-deposited thin film on the delay line. The interdigitated transducers and delay lines are fabricated by photolithography techniques on a single Y-cut LiNbo3 substrate oriented for Z-propagation of the acoustic waves. Variation in electrical conductivity of the Au-activated TiO2 film due to exposure to metastable He is translated as a frequency change in the assembly. Various characteristics of the surface acoustic microsensor have been studied to better understand and optimize the variation of acoustic wave velocity and the operating frequency of the microdevice. Methods for the TiO2 thin-film deposition are discussed.