MAGNETIC TEMPLATE BASED ASSEMBLY OF SUPERPARAMAGNETIC COLLOIDAL PARTICLES
B. Yellen, G. Friedman
Drexel University, Department of Electrical and Computer Engineering, US
Keywords: superparamagnetic, self-assembly, biochemical, array, colloidal, biosensor
A two-dimensional array of colloidal particles can be utilized in constructing devices and materials for photonic, electronic, magnetic and sensor applications. Several methods for patterning colloidal particles arrays have emerged in the recent past, including surface chemistry, electrostatic, and surface tension driven assembly of colloidal particles. In contrast with these methods, magnetic template driven self-assembly can offer significant advantages. One advantage is that magnetic forces can act on magnetic particles at relatively long-range, compared with chemical, surface tension, and Van der Waals forces, which act at short-range. Another advantage is that the highly nonlinear behavior of magnetic materials can be exploited to generate both attractive and repulsive forces on colloidal particles. In particular, the ability to generate repulsive forces can be used to prevent designated array sites from being patterned with colloidal particles, which opens the possibility for assembling heterogeneous colloidal particle arrays.
Numerical modeling of nano- and micro-particle assembly onto a surface driven by ferromagnetic templates and external uniform magnetic fields will be discussed and accompanied by experimental validation of the model. Experimental investigations employ thin ferromagnetic islands, fabricated through conventional photolithography, aligned with a protective layer of micro-wells to attract magnetic particles from colloidal suspension.
NSTI Nanotech 2003 Conference Technical Program Abstract