Table 3.

Comparison table of proposed sensor and non-RF sensors.

References	Sensing Materials	Contact	Fabrication Complexity	Sensitivity	Limit of Detection
[41]	Ethanol gas	contact	Complex	31.4 †	10 ppm @ 300 °C
[50]	Ethanol liquid	contact	Complex	57.3 †	100 ppm @ 400 °C
[51]	Ethanol vapor	contact	Complex	4.6 †	300 ppm @ 350 °C
[52]	Ethanol gas	contact	Complex	24.5 †	50 ppm @ 25 °C
[53]	Ethanol vapor	contact	Complex	19.6 †	10 ppm @ 220 °C
This Work	Ethanol liquid	Non-contact	Simple	49.1 †† MHz/εr	78,990 ppm

^† Sensitivity is defined as a ratio of resistance of air and gas (R_air/R_gas); ^†† Sensitivity is defined as a Δf/Δε_r.