In the world of electronics, size really does matter. The smaller the component parts, the faster, more accurate and more efficient the electronic device. But is there a limit to how far one can shrink electronics? Could one, for instance, connect a wire to a single molecule and then measure the electrical conductivity of that molecule? It took a surprising combination of scientific talent to achieve just that and, in the process, to push back the limits of miniaturization.
Prof. Israel Bar-Joseph, Head of the Weizmann Institute’s Condensed Matter Physics Department and Prof. Amir Yacoby of the same department had been exploring various ideas for creating nanosized electrical conductors for use in experiments. Among the ideas they conceived was that of devices that would combine organic molecules with a metal such as gold.
Meanwhile, Prof. Joseph Sperling of the Organic Chemistry Department has been researching how genetic information is processed in the cell. To follow the complex procedure by which the genetic information encoded in the DNA must be spliced together and edited before proteins can be made, Sperling affixes gold nanoparticles to messenger RNA molecules. This allows him to track their progress as they carry their encoded instructions from the cell nucleus to the ribosome (the cell's protein factory) in the body of the cell. It was the expertise he developed in fastening submicroscopic gold particles to single RNA and DNA molecules that led him from his chosen field into nanophysics.
One day Sperling knocked on Bar-Joseph’s door to discuss his detection method, and the scientists had a meeting of minds. They stuck gold nanoparticles onto either end of a small organic molecule called biphenyl. By itself, the biphenyl molecule is only about one nanometer long, but attaching it to the gold nanoparticles resulted in a structure that can be integrated into physics experiments. It took their combined efforts to then hook this structure up to the poles of a miniature electronic device, effectively turning the organic molecule into a tiny “wire ” for conducting electricity.
In the future, the scientists plan to develop means to control the electrical properties of the molecular wire. This ability will pave the way to developing the smallest nano-transistors yet and could usher in a new era in nanoelectronics.
Prof. Israel Bar-Joseph’s research is supported by the Joseph H. and Belle R. Braun Center for Submicron Research. Prof. Bar-Joseph is the incumbent of the Jane and Otto Morningstar Professorial Chair of Physics.
Prof. Amir Yacoby’s research is supported by the Rosa and Emilio Segre Fund, and the Joseph H. and Belle R. Braun Center for Submicron Research.
Prof. Joseph Sperling’s research is supported by the Joseph and Ceil Mazer Center for Structural Biology; the Helen and Milton A. Kimmelman Center for Biomolecular Structure and Assembly; the J & R Center for Scientific Research; and Lois Zoller. Prof. Sperling is the incumbent of the Hilda Pomeraniec Memorial Chair of Organic Chemistry.