Continuous Sorting and Washing of Cancer Cells from Blood Cells by Hydrophoresis

This paper describes continuous sorting and washing of cancer cells from blood samples by three-dimensional rotating flows and hydrophoretic cell focusing in a microchannel with slant trenches. Sample preparation for analysis of cancer cells such as sorting and washing is an important pre-requisite for their downstream analysis (i.e. enumeration or molecular characterization of cancer cells). Current cell separators, however, provide the capability of either sorting or washing. Washing process is routinely performed off-chip, preventing the automation of cell based assays and point-of-care diagnostics. We present here a microfluidic method for on-chip cell sorting and washing. Slant trenches on a channel floor generate rotational flow streams and enable manipulation of the streams to passively cross cancer cells which remain focused in their equilibrium position by hydrophoresis. Using this device, we sorted cancer cells from contaminant particles and simultaneously washed them with a clean buffer, achieving high blood cell rejection efficiency of 99.3% and washing efficiency of 99.0%. The device enables simultaneous sorting and washing of cancer cells which can facilitate high-performance, automated cancer cell analysis.