Fig 1.
The voltage is obtained by interrupting the tension Umax every T period during αT.
Fig 2.
Schematic view of olfactometer.
This “Lorig design” was modified by adding a dilution channel enabling its use with PWM.
Fig 3.
Chronogram of the activation of valves.
During the rest period, valve 7 delivers clean air. During the stimulation period, the odor pulse is delivered through valve 1–5 every T period and the flow is compensated with valve 6.
Fig 4.
Representation of the volumes delivered during a T period.
FA and FB correspond to the airflow managed by flowmeters A and B (Fig 2) respectively. In blue, the air volume due to the constant flow. In red and green, the volume of odor pulse and the volume required to keep a constant flow.
Fig 5.
Schematic view of the experimental paradigm.
After the countdown, odor is delivered and then, the participant rates its intensity. Each trial is followed by a rest period of 30 s.
Fig 6.
Gas chromatography measures of mixing factor K as a function of duty cycle α.
Graph shows average and standard error of mixing factor K gas chromatography measures as a function of duty cycle α.
Fig 7.
Measure of flow velocity during a stimulation (gray) and rest with airflow of 0.6, 1.2, 1.8 and 2.4 L.min−1 and with seven values of a duty cycle from 5 to 95% with step of 15%.
Fig 8.
Measure of air velocity oscillation caused by the use of PWM for airflow of 0.6, 1.2, 1.8 and 2.4 L.min−1 and with seven values of a duty cycle from 5 to 95% with step of 15%.
Table 1.
Post-hoc tests from ANOVA of intensity ratings.
Differences of intensity ratings between α for the three odorants, assessed with p values from the Bonferonni test.
Fig 9.
Graph shows averaged intensity ratings (± standard error) of the five α for butanol, IAA and pyridine. *: p < 0.05, **: p < 0.01, ***: p < 0.001.
Fig 10.
Setting up of a fast three-way valve in case the solenoid valves are too slow.
In case the solenoid valves are too slow, the pneumatic system can be improved by adding a fast three-way valve. This valve alternatively supplies the control/dilution channels and odor channels.