Hybridization experiments were traditionally performed using page-sized
filters, with each filter having about 10 bands displaying whether
hybridization occurred or not.
About ten years ago the techniques became developed enough to allow
miniaturized filters, which are chip sized, with each band being about 100
microns wide. Using these DNA chips, also called DNA arrays, also
enables us to perform several experiments at once.
There are two types of DNA chips, the difference being whether the target
DNA is on the chip or in the ``air'' (i.e. the solution to which the chip
is exposed). Table 11.1 summarizes the differences
between the chip types.
