Electronic microarrays from Nanogen contain 100 test sites laid out in a geometric grid. Each test site on the NanoChip array can be controlled electronically from the NanoChip Workstation's on-board computer. A permeation layer coated on the chip acts as a protective interface between the electrically active surface and the biological test environment. Molecules, including DNA and RNA, have natural positive and negative charges. With electricity, it is possible to facilitate both rapid movement to and from and concentration at designated test sites on the chip. Current applications include single nucleotide polymorphisms (SNPs), short tandem repeats (STRs), insertions, deletions and other mutation analyses.