DETECTION OF CHEMICALS BASED ON RESISTANCE FLUCTUATION-SPECTROSCOPY

摘要

The invention relates to a sensor-based electronic nose, and the general idea is to measure the noise fluctuations of the predetermined physical property, such as the resistance, of a sensor (120; 203; 213), and to determine a power-density spectrum of the noise fluctuations. The power-density spectrum of the fluctuations has turned out to be a sensitive tool for determining the composition of the chemicals applied to the sensor. The pattern of the power-density spectrum of the fluctuations is representative of the composition of the chemicals, and can be evaluated, manually or by means of an artificial neural network (160; 224), to determine the chemical composition. By dividing the power-density spectrum into a number of different frequency bands, where the nature of the response in each frequency band is different from that of the other bands, and using information of the power spectrum at each of these frequency bands, the number of sensors that are necessary to detect a given number of chemicals can be significantly reduced compared to conventional solutions.