(A) continuous particle separator based on gravity force and buoyant force in dissimilar density fluids

Abstract

This study presents a continuous particle separator to achieve density-dependent and size-independent particle separation based on gravity force and buoyant force on the particles immersed in dissimilar density fluids. The previous particle separators based on size or dielectrophoretic (DEP) property of particles are suitable for size-dependent and density-independent particle separation; thus having difficulty to collect particles such as RBCs and WBCs based on identical biological property. Also, they can give mechanical or electrical damage on particles. In this study, we propose a density-dependent and size-independent particle separator capable to collect particles based on identical biological properties without any particle damage. The present particle separator has a separation channel whose inlet and outlet are connected to the upper and lower channels, respectively. The fluid of lower density is supplied into the upper inlet channel while the fluid of higher density is entered into the lower inlet channel. The particles of two different densities, lower and higher density particle, contained in the upper inlet fluid tend to enter into the upper outlet channel and the lower outlet channel, respectively. We have designed the width, height, and length of the separation channel as $500\mum$, $200\mum$, and 8cm, respectively. The present particle separator was fabricated by SU-8 photolithography and PDMS molding process. For the polystyrene (PS) microbeads having the identical density of 1.05g/ml with the different diameters of $6\mum$ and $10\mum$, $6\mum$-bead and $10\mum$-bead were separated at the upper outlet with the maximum efficiency of $97.9\plusmm1.12%$ $6\mum$-bead and 100%. In the separation test of PS microbeads having the identical size of $6\mum$ with the different densities of 1.05g/ml and 1.5g/ml, the bead having density of 1.05g/ml and 1.5g/ml was separated at the maximum efficiency of $89.3\plusmm1.46%$ and 100%, respectively. In add...