DNA analytics is a growing field based on the increasing knowledge about the genome with special implications for the understanding of molecular bases for diseases. Driven by the need for cost-effective and high-throughput methods for molecular detection, DNA chips are an interesting alternative to more traditional analytical methods in this field. The standard readout principle for DNA chips is fluorescence based. Fluorescence is highly sensitive and broadly established, but shows limitations regarding quantification ͑due to signal and/or dye instability͒ and the need for sophisticated ͑and therefore high-cost͒ equipment. This article introduces a readout system for an alternative detection scheme based on electrical detection of nanoparticle-labeled DNA. If labeled DNA is present in the analyte solution, it will bind on complementary capture DNA immobilized in a microelectrode gap. A subsequent metal enhancement step leads to a deposition of conductive material on the nanoparticles, and finally an electrical contact between the electrodes. This detection scheme offers the potential for a simple ͑low-cost as well as robust͒ and highly miniaturizable method, which could be well-suited for point-of-care applications in the context of lab-on-a-chip technologies. The demonstrated apparatus allows a parallel readout of an entire array of microstructured measurement sites. The readout is combined with data-processing by an embedded personal computer, resulting in an autonomous instrument that measures and presents the results. The design and realization of such a system is described, and first measurements are presented.

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A portable and robust system which is suitable for the automated analysis of DNA or RNA of selected pathogens such as foot‐and‐mouth disease virus (FMDV) is developed. The system incorporates a stationary PCR chip and is coupled with a DNA chip and an electrical detection for the sequence‐specific identification of the PCR products. The PCR chip represents a miniaturized form of the classical thermocyclers and enables a fast and sensitive amplification as well as labeling of specific DNA sequences with minimal space and energy requirements. The detection and identification of the PCR products is performed on a DNA chip with an electrical detection scheme. The combination of the two technologies allows a very fast and highly specific sequence‐based detection and differentiation of pathogens. Further, it combines the accuracy of sequence analysis with the speed of chip technologies. For the total analysis including DNA amplification and DNA detection, less than 2 h are required.

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Rapid detection and accurate identification of plant pathogens in the field is an ongoing challenge. In this study, we report for the first time on the development of a helicasedependent isothermal amplification (HDA) in combination with on-chip hybridization for the detection of selected Phytophthora species. The HDA approach allows the efficient amplification of the yeast GTP-binding protein (Ypt1) target gene region at one constant temperature in a miniaturized heating device. The assay's specificity was determined by onchip DNA hybridization and subsequent silver nanoparticle deposition. The silver deposits serve as stable endpoint signals that enable the visual as well as the electrical readout. Our promising results point into the direction of a near future on-site application of the combined techniques for a reliable detection of Phytophthora species.