IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Biomaterials Tuesday Sessions
       Session BI+MM-TuM

Paper BI+MM-TuM11
Electrochemically-Activated Switching of Surface Chemistry Using Tethered Molecular Machines

Tuesday, October 30, 2001, 11:40 am, Room 102

Session: Biomems & Microdevices
Presenter: B.C. Bunker, Sandia National Laboratories
Authors: B.C. Bunker, Sandia National Laboratories
D.L. Huber, Sandia National Laboratories
J.G. Kushmerick, Sandia National Laboratories
M. Kelly, Sandia National Laboratories
C.M. Matzke, Sandia National Laboratories
J.F. Stoddart, University of California, Los Angeles
J. Cao, University of California, Los Angeles
J.O. Jeppesen, University of California, Los Angeles
J. Perkins, University of California, Los Angeles
Correspondent: Click to Email
Sandia National Laboratories is integrating "smart" coatings into microanalytical systems for transporting, separating, and detecting species such as proteins. This paper describes the first demonstration of the use of electrochemically-activated molecular machines to switch surface chemistries. The "motor" for the machines being studied consists of an open aromatic ring system (cyclobis(paraquat-p-phenylene)) referred to as the "blue-box" due to its strong optical absorption properties. Reversible oxidation or reduction of the blue box makes it attract or repel aromatic threads such as functionalized naphthalenes or tetrathiafulvalene (TTF). Researchers at UCLA have succeeded in attaching a disulfide-terminated tail to the blue box which is used to tether the blue box to gold surfaces. Ellipsometry and atomic force microscopy measurements indicate that monolayer films of the blue box are produced. Electrochemical measurements indicate that while the voltages required to reduce the blue box are similar to voltages known to induce switching of the box in solution, adsorption of naphthalene threads is irreversible. Reversible switching is only seen for TTF threads that can themselves be oxidized. Contact angle measurements show that reversible changes in surface chemistry can be induced using appropriate threads. A simple microelectronic device has been constructed to demonstrate how the molecular machines can be used to move liquids or dissolved species within microfluidic systems.