In recognition tunneling (see figure) each of the two electrodes is modified with an adaptor molecule that binds strongly to the electrode material and forms non-covalent bonds with the target analyte molecule. When the analyte binds across the shortest path, stochastic noise is generated that is characteristic of the binding of the analyte. This noise can be used to identify the four DNA bases, for example, as well as methylated cytosine, a DNA modification important in silencing genes. Not only is palladium compatible with CMOS technology, but it also gives much bigger signals than an equivalent gold junction.

This technology is being developed for DNA sequencing and the current work is the result of a collaboration between scientists at Arizona State University, Roche (454 Life Sciences) and IBM’s T J Watson Research Center.

More information can be found in the journal Nanotechnology.