A DNA microarray represents a technological platform able to detect and quantify thousands of biological elements present in a sample.

The technology, developed in the field of bio-medical research, has been mainly used to simultaneously examine the expression of thousands of genes or to detect the presence of genetic sequences of pathogenin micro-organisms (viruses, bacteria). However, it can also find application in fields, such as veterinary, agriculture, environment monitoring. The approach can be used for the high-throughput detection of micro-organisms in water and food.
A DNA microarray is made of an ordered grid of DNA probes linked to a solid surface, about few centimeter square in size. On this surface thousands or hundreds of thousands of probes able to detect the same number of genetic elements can be physically linked 3. If the specific probe is present on the microarray, then the biological element can be detected based on the sequence homology between nucleic acids (DNA or RNA). In other words, the intrinsic genetic characteristic of the biological element is used for its detection.

Microarray technology employs an inverse hybridization approach: it is the sample's nucleic acid (DNA or RNA) that is labelled (with a fluorochrome) instead of the probes. Then, the complex mixture of genetic elements that are present in each sample are allowed to hybridize (anneal to the specific probe on the basis of sequence homology). Based on its sequence homology, each microarray probe hybridizes to the homologous elements among the thousands that are present in each sample and allows the quantification of each one of them. Thus, this techniques allows the simultaneous detection and quantification of thousands of genetic elements.