The major limitation of blotting procedures is the length of time needed and the fact that they can accommodate only one probe at a time. DNA microchip technology permits the analysis of thousands of genes at the same time. DNA molecules are attached to the wafers in an organized array and are called the probes.
DNA molecules taken from tissues are hybridized to the chips and are called targets, which are labeled with fluorescent light. The probes that have hybridized to the fluorescent targets are then identified by fluorescence microscopy.