This invention relates to using customize oligonucleotide microchips as biosensors for the detection and identification of nucleic acids specific for different genes, organisms and/or individuals in the environment, in food and in biological samples. The microchips are designed to convert multiple bits of genetic information into simpler patterns of signals that are interpreted as a unit. Because of an improved method of hybridizing oligonucleotides from samples to microchips, microchips are reusable to transportable. For field study, portable laser or bar code scanners are suitable.
 The U.S. government has rights to the invention pursuant to contract W-31-109-ENG between the U.S. Department of Energy (DOE) and the University of Chicago representing Argonne National Laboratory.