A DNA chip is a device usually size of a microscope slide containing thousands of pre-defined spots. Each of these spots hosts a unique probe that can bind to a specific target gene sequence. When a sample such as prepared and purified blood comes in contact with the surface of the DNA Chip, the matching gene in the sample can pair with the probes on the DNA Chip. The researcher, then, uses a computer program to analyze the position of the spots to identify targets such as pathogens, mutations, etc.. in the sample.