The present invention is a biosensor apparatus that includes a substrate,
a source on one side of the substrate, a drain spaced from the source, a
conducting channel between the source and the drain, an insulator region,
and receptors on a gate region for receiving target material. The
receptors are contacted for changing current flow between the source and
the drain. The source and the drain are relatively wide compared to
length between the source and the drain through the conducting channel.