Bidirectional Cell Sliding on Active Tracks for High Throughput Dielectrophoretic Cell Sorting in Continuous-Flow

Dielectrophoretic (DEP) cell sorting platforms working in continuous mode are advantageous over those in batch mode due to their expanded sample capacity, fast processing as well as simple operation. State-of-art DEP activated cell separators leverage continuous-flow cell sorting with slanted digits made of metal film patterned on channel bottom or 3D bulk electrode embedded in channel sidewall, which project DEP force field that laterally deflect the cells as they proceed in the channel. However, these designs have limited channel depth or width which hamper their volumetric flow rate. Recently we report a design of interdigitated silicon electrode digits that serve as tracks for cell railing during the separation and achieve cell separation at 8.3 μl/min with 86% separation efficiency for the separated cells. Yet the fabrication process for tailoring the silicon electrode digits involves expensive silicon dry etching process and requires specially designed pattern of the digit featuring non-straight wavy outline, which leads to non-uniform drag force acting on cells. Here we innovatively enable bidirectional cell sliding on V-shaped 3D interdigitated electrode digits that serve as perfectly straight sliding tracks. Such ideal sliding tracks significantly enhance the throughput compared to the existing silicon tracks. The electrodes made of silver-PDMS (AgPDMS) composites are fabricated using low-cost soft-lithography process. Bidirectional cell sliding is demonstrated using Hela cells, and high throughput separation of Hela cells from beads is showcased with 85% cell separation efficiency at 20 μl/min sample infusion flow rate.