AVS 52nd International Symposium
    Nanometer-Scale Science and Technology Monday Sessions
       Session NS2-MoA

Paper NS2-MoA10
Directed Assembly and Real-Time Electrical Detection of Nanowire Bridges

Monday, October 31, 2005, 5:00 pm, Room 210

Session: Nanometer Scale Assembly
Presenter: L. Shang, University of Wisconsin-Madison
Authors: L. Shang, University of Wisconsin-Madison
M. Marcus, University of Wisconsin-Madison
J. Streifer, University of Wisconsin-Madison
B. Li, University of Wisconsin-Madison
R.J. Hamers, University of Wisconsin-Madison
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We have explored the use of dielectrophoretic manipulation combined with biomolecular recognition to control bridging of individual metallic and semiconducting nanowires across micron-sized electrical gaps. While dielectrophoretic manipulation is only temporary, more permanent assembly can be achieved using biomolecular recognition. For example, while biotin-modified nanowires interact only weakly with bare Au electrodes, they bind strongly to avidin-modified electrodes. The bridging of a nanowire across the gap can be detected electrically even though the nanowire is spaced away from the gold contact by the biomolecular contact. We have develop a novel method for achieving real-time monitoring of nanowire bridging events, using one AC electric field to manipulate the wires and a second field to measure the changes in electrical response induced by nanowire bridging. Because the change in electrical response is primarily capacitive, detection of bridging events is most sensitively achieved at higher frequencies, on the order of 1 kHz-100 kHz. At a fixed measurement frequency, we observe a step-like increase in current when a nanowire bridges the electrodes. Individual silicon and metal nanowires can be detected visually as well as electrically, allowing visual confirmation of the origin of the electrical response.