The master's thesis deals with the question of breath analysis using chemiresistors as detection elements for exhaled air analysis. Emphasis is placed on the application of fluctuation-enhanced sensing for chemiresistors for breath analysis, construction design of usable measurement system, and its calibration. Compared to the usual concept, which includes various methods ranging from DC processing in time to controlled impedance measurement, this method of signal analysis focuses on the evaluation of fluctuations and determination of indicators of its change in dependence of change in detected substance concentration.