Making electrical contact
to single molecules
W. Fritzsche*, E. Ermantraut,
H. Porwol, J.M. Koeumlhler
Institute
of Physical High Technology
This is an abstract
for a poster to be presented at the
Fifth
Foresight Conference on Molecular Nanotechnology.
The full paper is available here.
We are interested in the characterization of the electron
transport through single (bio)molecules. A prerequisite for
electrical measurements is the contacting of molecules in the
nanometer range, which was accomplished by two different
approaches.
The first approach is based on statistically distributed
molecules, which were visualized by scanning force microscopy
prior to structuring of electrodes by means of electron beam
deposition or electron resist technique. The structured
nanoelectrodes were characterized by scanning force microscopy
and electrical measurements.
Another approach for contacting includes the binding of one
end of the molecules to an electrode followed by an induced
orientation of the molecule toward the second electrode. A
thiol-biotinylated gold surface was used as a substrate. We used
a wet-masking technique which we call micro offset printing in
the case when multiple alignment steps lead to synthetic
structures. The parts of the substrate to be protected were
covered by an elastomeric mask and were therefore not accessible
for activation reagents. The surface density of the desired
molecules was adjusted by dilution of the active thiol-biotin
with an inactive component, and the result was monitored by
contact angle measurements. An induced orientation of
biomolecules was accomplished using flow adsorption or a receding
meniscus.
*Corresponding Address:
Wolfgang Fritzsche, Institute for Physical High Technology, Jena,
P.O. Box 100 239, 07702 Jena, Germany, ph: +49 3641 657744, fax:
+49 3641 657700, [email protected]
|