The purpose of the analysis was to present the possibility of the sensitivity improvement of the electronic nose (e-nose) and to summarize the detection mechanisms of trace gas concentrations. denseness in graphene by attaching a substituent and stabilization of electronic charge distribution prospects to the increase of graphene sensor conductivity. The complexation of porphyrins with selected metals stabilizes the electronic system RFWD1 and increases the level of sensitivity and selectivity of porphyrin-based detectors. Our research summary and proposed conclusions allow us to better understand the LY2794193 mechanisms of a radical switch of graphene conductivity in the presence of trace amounts of numerous gases. Keywords: graphene, electronic nose, carbon nanotubes, porphyrins, conductive polymers 1. Intro Molecular mechanisms of detection of trace amounts of gases have been studied for many years. Moreover, different analyses and data interpretation methods have been developed over the past decades. These achievements allowed us to get more detailed insights into the concept of electronic nose (e-nose) which represents a method that is complementary to the commonly used GC-MS technique (gas chromatography combined with mass spectrometry). In contrast to GC-MS, the use of the e-nose does not allow for direct chemical identification of the particular substance, but it can show the final specific response of the sensors to the analyzed substance present in the sample and assign it to a specific group of compounds. Moreover, the e-nose method may allow for the production of small, inexpensive and user-friendly devices that can be used in different areas where gas identification mechanisms play a significant role (e.g., industry applications, healthcare, food and air quality control, etc.). An electronic nose is a model of the mammalian olfactory system. According to the Axel and Buck theory (Nobel Prize, 2004), the perception process begins in the olfactory epithelium, where approximately fifty million receptor neurons initially identify and classify volatile molecules [1]. Each of neurons is equipped in a dendrite ended in a bulb, from which cilia extend. G-protein coupled receptors, which were described by Robert Lefkowitz and Brian Kobilka (Nobel Prize in chemistry, 2012), are located on the surface of cilia LY2794193 and play the role of chemosensory receptors [2]. The scale of similarity of the molecule shape to the pattern assigned to the receptor corresponds LY2794193 to the intensity of the electric impulse. A single receptor is activated by many odors and a substance can be recognized by many receptors. The receptor, when a matching molecule is detected, starts transmitting by triggering the starting of ion stations in depolarization and neurons of the cell membrane. The electric potential difference movements to the synapse also to the dendrites of postsynaptic neurons finally. Currently, research is targeted on applying LY2794193 the e-nose in medical areas, especially in the first diagnosis and avoidance of respiratory illnesses (i.e., lung tumor) using, amongst others, quartz microbubbles aswell as detecting the current presence of bacterias in the urine as well as the eyeball using polymer detectors [3]. The e-nose offers diagnostic features for kidney also, prostate, bladder, and Parkinsons disease [4 actually,5,6]. This incredibly interesting technology must be improved with regards to features linked to cost or size but undeniably it’ll be significantly introduced into our day to day life because of its dependability and advantages over regular odor analysis strategies [7]. The introduction of artificial olfaction strategies would not become so dynamic with no execution of different strategies that enable a detailed evaluation of data models of detectors arrays. Here, we wish to highlight both most well-known and useful methodsprincipal element evaluation (PCA) and cluster evaluation (CA). PCA can be a dimensionality-reduction technique that’s utilized to lessen the dimensionality of huge data models frequently, by transforming a big set of factors into a smaller sized one which still contains a lot of the info from the huge set. Through the use of dimensionality decrease, we trade just a little precision for simplicity. The reason behind that is that smaller sized data models are better to explore and visualize which makes analyzing data much easier and faster for machine learning algorithms without extraneous variables to process. Thanks to PCA analysis, sensors are assayed for their responsibility for the vapors classification. Sensors with loadings ~ 0, for a particular principal component, have a minor contribution to the total response of the array, whereas, high values show discriminating sensors. According to this theory, sensors that have an inconsiderable responsibility for the distribution pattern in the PCA.