Table 4.
Comparison of operating frequencies, noise level and sensitivities of QCM, SAW and thin film bulk acoustic resonator (TFBAR) devices for chemical sensing of ethyl acetate and toluene vapors. All the devices were coated with 75 (wt.%) SWCNT-based nanocomposite Langmuir–Blodgett layers, adapted with permission from [182].
| Acoustic Device | Operating Frequency (MHz) | Noise Level (Hz) | Sensitivity (ΔF/c) ΔFw (Hz/ppm)/kHz | |
|---|---|---|---|---|
| Ethyl Acetate | Toluene | |||
| QCM | 10 | 1–5 | 0.05 | 0.097 |
| SAW | 433 | 10–25 | 0.30 | 1.020 |
| TFBAR | 1045 | 50,000 | 0.98 | 1.044 |
ΔF referred to frequency shift due to gas exposure; c is the concentration of gas; ΔFw is the frequency shift due to coating onto device.