California Institute of Technology researchers have developed a method of “demultiplexing” the signals from ultrahigh-density nanowire circuits — electrically addressing large numbers of individual nanowires using many fewer electrical connectors.

The technique will help in analyzing the complex signals that such sensors generate when they are testing complex biological samples.

Dr. Heath, who is a principle investigator of one of the NCI’s Centers of Cancer Nanotechnology Excellence, and his collaborators used standard lithographic techniques to deposit pairs of conducting metal lines perpendicular to the nanowires, which all run parallel to each other. By passing an electrical current through the pairs, and varying which pairs are powered, the researchers are able to address an individual nanowire and determine its electrical status.

For example, nanowires coated with a tumor biomarker detection reagent, such as an aptamer or antibody, display sharp changes in electrical behavior when those reagents bind to the biomarker they are designed to detect.