Figure 9.

(A) Sensor responses of 80, 301, 433 and 1000 MHz SAW sensors against 1000 ppm of toluene vapors, along x-axis the f_o represents fundamental resonance frequency, all the devices were coated with permethylated β-cyclodextrin linked with hexafluorobenzene having thickness 60 nm, adapted with permission from [170]. (B) Sensor responses of 80, 315, 433, 915 and 1000 MHz SAW sensors against 100 ppm of different vapors, all the devices were coated with ZnO-CuO-CNT nanocomposite, adapted with permission from [171]. In both figures, sensor response increases as the resonance frequency of SAW resonator increases.