Jun 13, 2008
Conductance screening tool rapidly measures single molecule conductance
Molecular-scale electronics has made significant strides in recent years, and it has even become possible to measure the electrical response of a single molecule connected to two electrodes. Such advances are extremely important in the development of molecular electronics, nanoscale sensors, and the measurement of biologically relevant molecules, such as DNA and amino acids. However, one of the major issues in single molecule electronics is the capability to quickly and reliably measure the conductance of a single molecule junction.
A recent article in Nanotechnology introduces the Conductance Screening Tool for Molecules, or CSTM. The conductance of a single molecule junction can change significantly from one junction to another due to changes in the contact geometry or the configuration of the molecular junction. This requires that many measurements be made to determine the most probable conductance of a single molecule junction. Thus, to meet this need, the CSTM quickly creates thousands of single molecule junctions and analyzes the results to find the conductance a single molecule junction. This tool can create approximately 20,000 individual junctions per hour, which is a vast improvement over previous tools, and opens the door for a variety of systematic studies of families of molecular systems to better understand how to predict and control the conductance of a molecular junction.
Beyond just improving the speed of single molecule measurements, this tool is also proven in two additional important areas. First, the device is shown to work in an array-based measurement with a simple 3 × 1 array. Such measurements could be extremely useful in continuing molecular electronics research where a single preparation cycle could be used to perform measurements on thousands of molecular junctions providing superior throughput and large-scale systematic measurements.
The CSTM is also used to find the conductance of amino acids, the building blocks of peptides and proteins. Here it is shown that the CSTM works in aqueous solution and can be used to perform measurements on biological samples. Such a tool may be able to electrically read sequence information from DNA, or provide new insights into electron transfer in biological samples, as such it is imperative to demonstrate the utility of this new tool for biological samples.
Continued work in this area will allow large-scale arrays to be investigated for biological samples such as DNA and peptides, and will also focus on new molecular systems for demonstrating relevant electronic effects, such as negative differential resistance and efficient gating of a molecular junction.
About the author
Joshua Hihath is a postdoctoral researcher at Arizona State University in the department of electrical engineering. Nongjian Tao is a professor of electrical engineering at Arizona State University.