Application of a Low-Cost Electronic Nose to Detect of Forest Tree Pathogens: Fusarium oxysporum and Phytophthora plurivora

Abstract

The presence of forest tree pathogens may lead to substantial problems and their early detection in the stage of seeds storage or nurseries may be critical for the choice of appropriate management strategy. A new construction of a low-cost electronic nose was tested on the samples of pathogenic fungi and oomycetes of Fusarium oxysporum and Phytopthora plurivora. The electronic nose uses Figaro Inc. TGS series sensors with applied heater voltage modulation. Such a mode of electronic nose operation may be more appropriate for application for constant monitoring of seeds storage, when we compare it to the the method applying modulation of the gas concentration. A rectangular shape of the sensors' heater voltage modulation pattern, with a shallow drop of the heater voltage from the nominal voltage, was proposed. Data visualization using the principal component analysis method and the random forest machine learning technique used to build classification models. The classification accuracy of 97% was obtained by a fusion of data collected by TGS 2610 and TGS 2602 sensors.

Development of a Low-Cost Electronic Nose with an Open Sensor Chamber: Application to Detection of Ciboria batschiana

“…The previously reported low-cost electronic noses built in our laboratory [ 32 , 33 , 34 ] were constructed as a round probe, fit to the size of a Petri dish or jar opening hole, and manually moved from the clean air conditions to the measured sample. The noses were used to classify samples of pathogenic oomycetes Phytophthora plurivora, Pythium intermedium and fungi Fusarium oxysporum, Rhizoctonia solani .…”

“…The electrical circuit and sensors used in our electronic nose device are basically the same as it was used in the previous construction for our team [ 34 ]. For the reader’s convenience, we would like to provide here a short summary of it.…”

“…The changes could be made in every single sensor reading cycle from 0 to 7 V with a step of 30 mV. We modulate the voltage supplied to the sensor heater in the same manner for all sensors mounted in the device [ 34 ]. That allows for keeping the construction of the electronic nose simple and low-cost.…”

“…There are several types of electronic circuit topologies commonly used for the capture of the MOX sensors’ response [ 48 ]. In our case, we measure the voltage on a resistor serially connected to the sensor [ 32 , 33 , 34 ]. In Figure 4 , we present an example of a typical shape of measured response from one of the sensors.…”

“…At the moment of starting each observation time, a magnitude of the sensor response is used to normalize the response characteristics in that stage of observation [ 34 ]. Such responses can be used to extract the features that are used for training classification models used for differentiation between studied sample categories.…”