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For the detection of bacteria in potable water, several kinds of biosensors could be used. However, any of them faces its physical limits when very low concentrations of bacteria should be detected. In this article, we used micromechanical filters with perforated membranes for capturing and enriching bacteria and to facilitate the detection of Escherichia coli. The results in this article show the easy and effective removal of bacteria from the surface of the microsieve membranes. By plating off the filters on LB agar plates, we could quantitatively analyze very low concentrations of bacteria and show that micromechanical filters are potentially suitable for subsequent transfer of bacteria to a biochip for further analysis. In addition, direct immunodetection of nonpathogenic E. coli O157:H7 on micromechanical filter surfaces by fluorescent‐labelled polyclonal antibodies is demonstrated. In summary, micromechanical filters present a promising tool for future detection of bacteria in potable water. PRACTICAL APPLICATIONS There are two major fields of applications: (1) Laboratory analytics: Samples of water, blood or other aqueous solutions can be quickly analyzed for bacteriological contaminations using micromechanical filters for extraction; and (2) Field applications for quick monitoring of potable water quality become possible using a mobile detection system based on the micromechanical filters for sampling and simultaneous detection on the filter surface.

The quality and safety of drinking water is of major importance for human life. Current analytical methods recognizing viable bacteria in potable water are time consuming due to a required cultivation step. Fast and automated detection of water borne pathogenic microorganisms with high sensitivity and selectivity is still a challenging task. We report on a novel biosensor system using micromechanical filters with nano sized pores to capture and enrich bacteria on the filter surface. Thus the accumulated organisms are accessible to different detection methods using fluorescent probes. depending on the kind of detection - specific (identification of a certain species) or unspecific (total amount of cells) - different assays are applied. For non-specific detection we use fluorescent dyes that bind to or intercalate in the DNA molecules of the bacteria. Upon binding, the fluorescent signal of the dyes increases by a factor of 1000 or more. Additionally, we use enzyme substr ates for the detection of active ce lls. The whole detection process is automated by integrating the microsieves into a fluidic system together with a high performance fluorescence detector. 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 - is not only possible with ideal media, e.g. laboratory buffer solutions, but also with tap water. These results show the potential of microfilters for several applications in fast pathogen detection