Comparison of Several Optical Methods for an Automated Fungal Spore Sensor System Concept

Abstract

Molds and their spores are important to the global ecosystem. Thus, the thousands of different mold species are present worldwide and their spores can be found almost everywhere. Dangerous fungal contaminations that pose threats to the economy and human health are problematic especially in the areas of public buildings (hospitals), food industry (food transport), and private residences. A simple and cost-effective sensor system for the detection of fungal spore concentrations in air would minimize this risk. This paper presents an optical sensor system developed for the detection of airborne spores. Results from both this paper and the functional tests of the fabricated parts were used to develop a concept for a fully automated fungal spore sensor system, which can detect a contamination within minutes. This sensor system is based on a commonly used manual technique, in which the pictures of particles in air samples are analyzed. In the first step, the particles in an air sample were collected and fixed onto an adhesive surface. Afterward, the images were captured using a color camera and a microscope objective. The system allows images to be captured under three different microscopy methods: bright-field, dark-field, and fluorescence microscopy. The images were subsequently analyzed by software, and the analysis results from the three microscopy methods were compared. The results showed that the system was able to detect, differentiate, and count spores within minutes. This system also offers the major advantage of not requiring any prior incubation. Furthermore, based on the innovative use of adhesive tape that can serve as an automated microscopy surface, the system can be made simple and cost-effective to operate.