Effect of Flow Rates on Generation of Monodisperse Clay-Poly(N-isopropylacrylamide) Embolic Microspheres Using Hydrodynamic Focusing Microfluidic Device

Abstract

Vascular embolization is a minimally invasive nonsurgical technique obstructing a blood vessel by lodgment of embolic materials to treat cancers and vascular lesions. In this paper, we have carried out a parametric study of generation of monodisperse clay-poly(N-isopropylacrylamide) (clay-PNIPAAm) embolic microspheres of which size is comparable to a blood vessel (about 400 mu m). To achieve monodisperse water-phase clay/NIPAAm microdroplets, we have designed and fabricated a poly(dimethylsiloxane) (PDMS) hydrodynamic focusing microfluidic device (HFMD) for the generation of microdroplets with the affinity of continuous oil-phase fluid to the hydrophobic PDMS taken into account. We have investigated the influence of process-related flow conditions on the microdroplet generation to determine a proper processing window for obtaining monodisperse microdroplets with the fabricated HFMD. A parametric study of generation of monodisperse microdroplets was carried out by changing volumetric flow rates of two immiscible fluids within the determined processing window. For the suggested condition, the fabricated clay-PNIPAAm microspheres of about 400 mu m in diameter showed an extremely narrow size distribution with a coefficient of variation of 0.41%. We have also showed the floatability of the fabricated clay-PNIPAAm microspheres in saline and the smooth passage of the microspheres through a commercially available microcatheter as in vitro characterization for embolization. (c) 2011 The Japan Society of Applied Physics