THE CITY COLLEGE OF NEW YORK
CHEMICAL ENGINEERING DEPARTMENT
Graduate Student Symposium
City College of New York
Monday, March 5, 2018
Seminar will be held in MR-1307 (Marshak Building) at 2:00 PM
Reception will be held in Steinman Hall, Exhibit Room – 1st Floor
From 3:00 – 3:30 PM
In-situ Microfluidic Measurement of the Dielectric Constant of Colloidal Particles
The ability to manipulate micron-sized colloidal particles or biological cells in a liquid medium in microfluidic geometries is necessary in lab on a chip device for micro scale biological analysis and diagnostics for sorting and directing the trafficking of the particles. In dielectrophoresis, a nonuniform electric (E) field is applied to move the particles along the gradient of the field energy, and the velocity is a function of the particle's dielectric constant. Measurement of the dielectric constant is necessary in order to scale field strengths for applications, and it is important to undertake this measurement in-situ as the particle's dielectric content can be modified by the suspending medium (e.g. adsorption onto the particle surface). In this talk we measure directly the dielectric constant of colloids in a microfluidic channel by applying an electric field with ``V''-shaped and planar electrodes on opposite sides of the channel. The cusp of the ''V'' shape concentrates the field to provide a sufficient field intensity gradient which is designed to be uniform across the height of the channel and to vary only with its width. Optical measurements of the diffusiophoretic velocity of polymer colloids are compared to simulations based on numerical solution of the E-field and particle hydrodynamics to obtain the particle dielectric constant and investigate the effect of biomolecule adsorption on the particle surface.
Setareh Manfirasi obtained her bachelor’s degree in chemical engineering from the University of Tehran, Iran, in 2011. She joined CCNY’s chemical engineering Ph.D. program in 2012 and currently works with Professor Charles Maldarelli.