Silica Particle Characterization by Dielectrophoresis

Project: Research project

Project Details

Description

Silica Particle Characterization by Dielectrophoresis Silica Particle Characterization by Dielectrophoresis. The project will yield a simple, practical industrial product output, as well as parallel progress with academic research goals. We aim to use existing technology developed in-house (ASU) to separate and concentrate particles that are already purified via all accepted metrics (monodisperse, narrow zeta potential distribution, etc.) into ultrahomogeneous populations with respect to their 1) size, 2) surface charge, 3) surface charge homogeneity, 4) permittivity, and 5) permittivity heterogeneity or their electrostatic/dynamic properties. Developing and applying our technology to such a study on otherwise well-characterized samples will provide an opportunity to explore the physics of field-analyte interactions and aid further develop this approach. Microfluidic electrokinetic approaches have proven effective and versatile for the separation and manipulation of micro- and nano-particles. Dielectrophoresis (DEP) in particular presents key benefits over traditional separation schemes. The dielectrophoretic response of a particle depends not only on its size and charge, but also on surface charge heterogeneity, permittivity, and permittivity heterogeneity. Simultaneously probing all these properties allows for subtle differentiation of otherwise similar particles. Dielectrophoretic force is produced when inhomogeneous electric fields interact with permanent or field-induced dipoles. It can act upon neutral or charged particles, in combination with other electrokinetic forces such as electrophoresis (EP) or electroosmotic flow (EOF). Used in concert, these forces allow simple, addressable flow control and bulk particle handling within a microfluidic device. Recent innovations from this research group (Hayes, ASU) have further improved upon the advantages furnished by dielectrophoretic and electrokinetic separations. The devices developed in our lab are capable of rapidly separating, capturing, and concentrating analyte particles that range in size from a few nanometers up to 10 m. This approach harnesses the separatory power of punctuated field microgradientsa new steady-state approach that dramatically minimizes particle dispersion and increases the selectivity of particle capture. Preliminary theoretical calculations predict 100-fold or greater improvement of selectivity compared to the best capillary electrophoresis separations available. The microchannels are created from inexpensive materials, such as polydimethylsiloxane (PDMS) and glass. Electric potential is introduced at each end of the channel, minimizing electrochemical interference from electrodes. Insulating features are patterned along a single channel, producing progressively increasing electric field inhomogeneities. These differing and distinct microgradients act as unique traps along the channel. Bulk particle motion is driven by a DC electric field, via a combination of EP and EOF. The particles are captured and focused at unique locations within the channel, depending upon their characteristic electrophysical properties. The sequentially varying nature of the field microgradients causes the particles to fractionate into very narrow distributions. Because this focusing produces very narrow bands, multiple separations are easily accomplished in series. Parallelization would allow for high-resolution arrays capable of rapid, dynamic fractionation of analytes into highly pure samples. Specific Objective: Investigate the applicability of gradient dielectrophoresis and related techniques to the high resolution isolation and concentration of particulates. Execute quantitative studies resulting in 1) examination of gradient dielectrophoretic forces on well-characterized particulates and 2) conditions or device design and operation to produce highly purified particles. Benefit to Agilent: Provide new separations capabilities and to generate highly purified particles with absolute uniform size, electrostatic and electrodynamic properties
StatusFinished
Effective start/end date2/1/131/31/16

Funding

  • INDUSTRY: Domestic Company: $70,000.00

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