Multilayered Conductive Nanofiber Mats for Enhanced Filtration

Name: Christian Baryla Home Institution: Virginia Tech NNCI Site: KY Multiscale @ University of Louisville REU Principal Investigator: Dr. Kevin Walsh - Assoc. Dean of Research, Speed School of Engineering, University of Louisville REU Mentor: Dr. Stuart J. Williams - Department of Mechanical Engineering, University of Louisville Abstract: Active microfluidic nanoparticle separation techniques, such as ultracentrifugation have no mechanism of sorting particles by their intrinsic electric properties and are limited by batch filtration. Dielectrophoresis (DEP) aided filtration offers a continuous throughput with the capability of sorting particulates which are nearly identical in size but differ in their electric properties. Polyacrylonitrile (PAN) nanofiber mats with mean fiber diameters 300-500 nm and mat thickness ~100 μm were prepared by electrospinning an 8% wt. solution of PAN dissolved in N, N -Dimethylformamide (DMF). Between the spinneret and collector plate, a voltage of 17 kV, distance of 18 cm and humidity of 25-30% were held constant. After electrospinning, the mats were stabilized at 240°C for 2 hours to ensure evaporation of all remaining solvent. Mats were coated on each side with ~160 nm Cr/Au via sputter deposition. An electrical connection to each face of the mat was required to induce attractive DEP forces between nanoparticles and fibers. The subsequent sputtered mats were then integrated into a liquid-tight flow device. Applying an alternating current signal to the mat while in the flow device is believed to entrap nanoparticles within the outer topography of the mat. Quantification of fluorescent particle entrapment is desired in future trials. Integration of our high-throughput mats may prove to increase the filtration rate of nanoparticles by at least an order of magnitude over current DEP-aided techniques.