Scalable Crossbar Junctions
Our group develops concepts for the integration of biomolecules (e.g. proteins) into electronic components for novel bioelectronic and biosensing devices. On this note, we fabricate metal – protein – metal junctions by the means of Soft Lithography. The gentle processing conditions of these techniques allow the fabrication of short free Crossbar junctions interconnected by redox active proteins. The crossbars can be considered as scalable device with capabilities of addressing less than 1000 proteins in one junction. This allows closing the gap between single protein experiments and large protein assemblies. The electrical properties of these junctions can be studied by conventional IV measurements.
The major challenge in bioelectronics (BE) as well as in molecular electronics (ME) is combining the assembly of complex biocomponents with common lithography techniques. In particular, BE demands gentle patterning processes, since biomolecules are fragile and require very specific conditions to conserve their functionality. An alternative to conventional lithography techniques is Soft Lithography (SL), which uses flexible, "soft" polymers for printing and imprinting processes. These techniques allow a very gentle, non invasive and precise deposition of electrodes. We use Soft Lithography to build Crossbar Arrays with molecular interlayers. The Crossbar Arrays were assembled from top and bottom metal electrodes with widths ranging from 500 nm down to 50 nm. The Crossbar architecture allows varying the number of active junctions in one array and the number of active molecules integrated into a single junction by changing the width of the electrodes. Our goal is to scale the number of electrically addressed molecules and to compare the IV characteristics of single and multi molecule junctions. Recently we demonstrated the feasibility of our process by integrating different conductive polymers into the cross point of 8x8bit crossbar arrays with feature sizes in the nanometer range.