Correlating Electronic Nose and Field Olfactometer for Industrial Odor Concentration Measurement Using PLS and MLR

Developed Electronic Nose Setup and Experimental Procedure

A portable electronic nose system was developed for the measurement of odor concentration (ou/m³) using commercially available metal oxide sensors. The sensors were procured from FIGARO, USA (Figaro, USA) of TGS series TGS 823, TGS 825, TGS 2610, TGS 2602, TGS 826, TGS 832, TGS 2620, TGS 2611. The TGS sensors are of thick film type, and the sensing element of the TGS sensor is tin dioxide (SnO₂) doped with different impurities. The developed system consisted of (a) stainless steel sample holder (the steel material had no reaction to the sulphurous odorants) (b) programmable suction pump (c) compressed pure air canister for purging of the leftover gases (d) data acquisition system and (c) olfaction software.

The sensors were fixed in a funnel-shaped chamber, the shape of which allowed equal gas exposure to all the sensors. A circular printed circuit board was used for fitting the sensors into the chamber. The chamber had a narrow inlet in the form of Teflon tubing to let the gas collected during sample suction process be exposed to the sensor array. During the purging process, an exhaust fan mounted on the chamber was turned ON to clean the system by removing the left over RSCs. The overall process of the electronic nose can be summarized as follows (1) Suction time = 10 sec, (2) Sample capture = 10 sec, (3) Sampling time = 20 sec, (4) Purging time = 300 sec. All the above operations along with PC – based data acquisition were controlled by specially designed software in LabVIEW® of National Instruments. The developed software helped in reduction of human error while handling a very dynamic thing like gas sample and allowed equal controlled injection of gas samples for repeated studies. Figure 1 shows the schematic of the developed electronic nose system.

Figure 1.

Electronic nose setup