Bret N. Flanders
Assistant Professor of Physics
Contact Information
Address: Oklahoma State University
Department of Physics
145 Physical Sciences II
Stillwater, OK 74078
Office: Rm. 248, Physical Sciences Building
Voice: (405) 744-6699
Fax: (405) 744-6811
Email: bret.flanders@okstate.edu
Lab: Rm. 543, Physical Sciences Building
Voice: (405) 744-2865
Background: Bret Flanders received his B.S. degree in chemical physics from UC San Diego in 1993 and his Ph.D. degree in chemistry from the University of Chicago in 1999 under the advisorship of Professor Norbert F. Scherer. After working as a NIH-NRSA supported postdoc with Professor Robert C. Dunn at the University of Kansas, he joined the faculty of the Department of Physics at Oklahoma State University in 2002.
Description of Research
The common theme of our experimental program in soft condensed matter physics is the directed assembly of nanoscale materials that shed light on fundamental growth processes and that are useful for new nano-biological applications.
See a recent write-up of our research in nanotechweb.org: [Link]
Directed Electrochemical Nanowire Assembly: This nanowire growth technique has been developed in our group over the past 2 years. In this approach, alternating voltages are applied to electrodes in simple salt solutions to induce the single-step growth and interconnecting of crystalline metallic wires. These wire may be connected to the electrodes with contact resistances that are of the order of 10 W. We have identified dendritic solidification, a long-studied mechanism in soft condensed matter physics, as an important component of this technique. A key characteristic of dendritic solidification is that the growth-velocity and tip-radius are anti-correlated. This relationship is exploited to realize diameter-tunable nanowire growth. The experimental parameter that provides this control is w, the frequency of the alternating voltage. Increasing w effectively steepens the metal cation concentration gradient at the wire-solution interface, thereby increasing the growth-velocity of the wire. For indium wires, increasing w from 0.5 to 3.5 MHz increases their growth-velocity from 11 to 78 mm/s and reduces their diameter from 770 to 114 nm. Gold wires exhibit diameter-tunability that ranges from 150 nm down to 45 nm. Thus, it is possible to tune the wire diameter from the microscale down to the nanoscale. Additionally, this work differs from most previous experimental studies of dendritic solidification in that it demonstrates non-stationary dendritic solidification.
Nanoscale Electrophysiology: Ion-mediated signaling plays a controlling role in nearly all biological processes, and the patch clamp technique is the primary means of studying localized voltage-gated events in live cells. However, due to the steric limitations of contacting multiple patch clamp pipettes to a single cell, a number of interesting electrophysiological processes remain uncharacterized. Directed Electrochemical Nanowire Assembly (DENA) is a new, biocompatible technique for growing crystalline, metallic nanowires from macroscopic electrodes to targeted sites in the interelectrode region. By growing multiple wires up to a set of targeted sites on single live cells, this technique could be used to deliver complex, spatially localized electrical stimuli to the cells. Our objective is to elucidate the early stages of voltage-gated Ca2+ signaling that are fundamental to processes such as contractile behavior and cell-migration.
Support
Oklahoma State University EPSCoR Funds for Nanotechnology
Oklahoma State University Environmental Institute
Some Recent Publications
1. B. Ozturk, I. Talukdar, and B. N. Flanders, "Directed growth of diameter-tunable nanowires," Nanotechnology, 18, 365302 (2007). [PDF]
2. B. Ozturk, T. D. Mishima, D. R. Grischkowsky, B. N. Flanders, "Single-step growth and low resistance interconnecting of gold nanowires," Nanotechnology, 18, 175707 (2007).
3. A. Su, S. Tang. P. Thapa, B. N. Flanders, and W. T. Ford, "Highly ordered Langmuir-Blodgett films of amphiphilic poly(propylene imine) dendrimers," J. Phys. Chem. C, 111 4695-4701 (2007).
4. I. Talukdar, B. Ozturk, T. D. Mishima, and B. N. Flanders, "Directed growth of single-crystal indium wires," Appl. Phys. Lett. 88, 221907 (2006).
5. B. Ozturk, C. Blackledge, D. R. Grischkowsky, and B. N. Flanders, "Structural and transport properties of reproducible interconnects dielectrophoretically assembled from gold nanorods," Appl. Phys. Lett. 88, 073108 (2006).
6. B. Ozturk, I. Talukdar, and B. N. Flanders, "The directed-assembly of CdS interconnects between targeted points in a circuit," Appl. Phys. Lett. 86, 183105 (2005). [PDF]
7. B. Ozturk, G. Behin-Aein, and B. N. Flanders, "Hard-disk behavior and beyond in Langmuir films of CdSe nanoparticles," Langmuir, 21, 4452-4457 (2005). [PDF]
8. B. N. Flanders, S. A. Vickery, and R. C. Dunn, "Divergent fluctuations in the molar area of a model lung surfactant," J. Phys. Chem. B, 106, 3530-3533 (2002). [PDF]
9. B. N. Flanders and R. C. Dunn, "A near-field microscopy study of submicron domain structure in a model lung surfactant," Ultramicroscopy , 91, 245-251 (2002).
10. B. N. Flanders, S. A. Vickery, and R. C. Dunn, "Imaging of monolayers composed of palmitic acid and lung surfactant protein B," J. Microscopy, 202, 379-385 (2001).