Fig. 2: Optimal electrical performance of the OGs.

a Heating temperature of OGs as a function of operation time with the target temperature variating from 35 to 55 °C. b Response time required to reach the target temperature with the measured stabilized temperature shown in (a). c Stabilized ethanol concentration generated by OGs as a function of heating temperature ranging from 35 to 55 °C. Here, the error bars are presented as the standard deviation, and the test was repeated 3 times by testing 3 different OGs. d, e) Stabilized ethanol concentration (d) generated by OGs as a function of frequency of AC power into the electromagnetic coil with the corresponding heating temperature variation (e). f Stabilized ethanol concentration as a function of amplitude of AC power into the electromagnetic coils. Here, the error bars are presented as the standard deviation, and the test was repeated 3 times by testing 3 different OGs. g Stabilized ethanol concentration as a function of AC power duty cycle, including 20%, 40%, 60%, and 80%. h) Ethanol concentration variations along with the operation time at the three different surrounding airflow rates, including 2.76 m/s, 4.12 m/s, and 6.61 m/s. i) Changes in ethanol concentration at the surrounding airflow of 2.76 m/s when the breathing holes are closed by manipulating the movement of magnet inside OGs. j Heating temperature variations along with the 12-h operation time with the target temperature of 55 °C. k, l 3D distributions of the stabilized ethanol concentration above OGs with the detailed 2D concentration at x = 0 mapped in l.