Single Tandem Repeats (STRs for short) are one of the ways that people differ from each other in their genetic sequences. STRs, also known as Simple Sequence Repeats (SSRs) or microsatellites, are sections of DNA in which a short sequence pattern (typically 2 to 6 base pairs) repeats many times. The number of times a pattern repeats varies between people. Some of the repeats happen in areas of the genome which are not used. But there are also repeats that happen in genes and some of those variations in the length of repeats are known to affect the functioning of enzymes and other proteins that the cell makes from those genes.

STRs are important

This paper from the Whitehead Institute for Biomedical Research describes a method for assaying for STRs that can reduce the cost by an order of magnitude and which can be miniaturized into a portable device. The paper appears to be from 1998 or 1999.

http://www.ncjrs.org/pdffiles1/nij/188292a.pdf