Strands of DNA that pair with each other are complementary strands. When complementary strands attach to each other, it's called hybridization. Affixed to the glass biochip are many short strands of DNA called oligonucleotides. These short strands are between six and nine base pairs long. They are like a series of words written in the DNA alphabet.
Scientists prepare a solution of the DNA to be sequenced and apply a drop to the biochip.
The longer strands hybridize wherever there is a complementary oligonucleotide. Then a specially-designed microscope detects where the DNA hybridized. A computer attached to the microscope analyzes the data and in a few seconds can piece the word puzzle together into the correct sequence. Most other sequencing procedures use radioactive tags or labels. The fluorescent tags provide enough sensitivity for this procedure and are easier and safer for scientists and technicians to use.