Figure 2.

Basic operating principle for microfluidic electronic nose devices. Unlike electronic noses discussed in Section 2, the sensor array has been replaced with a single sensor coupled to a microfluidic channel. (A) Headspace sample containing a mixture of so analytes, red and blue. (B) Sample flows through microfluidic channel due to diffusion processes. Separation occurs due to adsorption on the channel walls. (C) Compound with the lowest retention time (time spent within the channel) will reach the gas sensor. This provides the user with a curve with features specific to the mixture of gases within the sample allowing for discrimination [84].