In addition to beads, nanorods can also be used as probes. Nanorods have a higher aspect ratio, which allows

• High total force

• Torques

• Bionic complex movement

Magnetic probes in 3DFMCISMM: Computer Integrated Systems for Microscopy and Manipulation

Collaborators: Kannan Krishnan from University of Washington

Project Director: Rich Superfine Investigators: Jing Hao, Jerome Carpenter, Lloyd Carroll, Tim O'Brien

http://cs.unc.edu/Research/nano/cismm/3d/index.html

11,21,2003

Magnetic nanorod probes:

To expand the abilities of the 3DFM in different fields covering from rheology study to fluidics research, we are building up an extensive magnetic probe gallery. Guided geometry, they are divided to 3 categories: magnetic beads, nanorods and ultra-fine nano-particle probes.

SEM pictures of some para-magnetic beads from the database

Applications of magnetic beads:

• Probes for force measurement

• Probes for rheology research

• Probes for 3 dimensional hose topography sensing

The addition of laser tracking in our 3DFM gives us a strong tool for manipulating the beads to measure specific properties. For example, we have demonstrated dragging a PS bead near a rotating nanorod. The vortex movement of that bead gives a unique way to do localized fluidics research.

Through Prof. Kannan Krishnan, we have access to nano-particles which range from 4nm and larger, in shapes including spheres, discs and rods, and variety of biomolecule functionalizations.

Nano-particles from Prof. Kannan Krishnan University of Washington

Application of nano-particles:• Force probes: due to their small size, they

have access to interiors of biological structures (vesicles, microtubules). Also, they would allow a distributed force to be applied instead of through the few linkages that would attach larger probes.

• Other applications: Drug Delivery by guiding functionalized nano-particles to specific tissues through designed magnetic fields and cell hyperthermia by magnetically heating them dispersed in tissue so targeted cell death can be induced for a possible cancer treatment.

Magnetic beads:

Ultra-fine Nano-particles

Magnetic beads come in many varieties: their different sizes, surface chemistries and dispersion methods allow a wide range of experiments. We have created a database to catalog the properties of our paramagnetic beads. Once the parameters for an experiment are set, its easy to look up the appropriate bead.

Purpose

Nanorods with diameters ranging from 20 – 200 nm and lengths up to 50 microns are fabricated by electro deposition inside of an Anodized Alumina Porous Membrane. Currently we have permalloy and iron nanorods, but numerous other types are available. The different magnetic properties of the iron and permalloy, however, make them excellent sensors in different application.

Single permalloy nanorod

Below: Diagram of Electro deposition

Above: Looking down on a forest of

rods after electro

deposition. (Membrane has been partially etched)

Above: Empty Anodized Alumina

Membrane

Fabrication of Nanorods

EDX data shows the rod left is permalloy with Ni:Fe ~ 90:10. The soft magnetic properties make them suitable for AC field situation.