An integrated system for automated bacteria sampling, enrichment and detection in water

摘要

Standard detection methods for viable bacteria in water are time consuming due to a required cultivation step. Fast detection of pathogenic organisms with high sensitivity and selectivity is still a scientific challenge. Mobile biosensors developed so far face their physical limits at very low concentrations of bacteria. We report on a novel integrated sensor system for sampling, enriching and detecting biological pathogens, e.g. bacteria in water. At the core of this device, there is a micromechanical filter having a large number of pores with a diameter of 450nm. When passing water through such filters, any bacteria (typical size of E. coli is approx. 1μm) present in the sample will be effectively captured on the filter surface. Once on the filter, the bacteria are easily accessible to any kind of specific or nonspecific detection method. After the first step of trapping the microorganisms on the filter surface, the optical detection step follows. Depending on the kind of detection method - specific (identification of a certain species) or unspecific (total amount of cells) - different assays are applied. To ensure realistic conditions, real potable water, i.e. including particles, has been spiked with defined amounts of microorganisms. Thus, sampling, enriching and detection of microorganisms - all with a single micromechanical filter - are not only possible with ideal media, e.g. laboratory buffer solutions, but also with tap water.