Sheath‐assisted versus sheathless dielectrophoretic particle separation

AbstractLab‐on‐chip devices are widely being used for binary and ternary cell/particle separation applications. Among the lab‐on‐chip methods, dielectrophoresis (DEP) is a cost‐effective and label‐free method, with great capabilities for size‐based separation of cells and particles, which is mostly performed in sheath‐assisted forms. However, the elimination of the sheath flows offers advantages such as ease of operation and higher sample throughput. In this work, we present a comparison of sheath‐assisted and sheathless DEP separation of three sizes of microparticles using tilted electrodes. The sheath‐assisted design was capable of separating the 5, 10, and 15 μm particles with a separation efficiency as high as 98.0% for 15 μm particles. By adding a DEP focusing region, a sheathless DEP separator was proposed, which offered higher throughputs (up to 10 times) at the cost of lowering the separation efficiency (a reduction up to 10.3% for 15 μm) compared to the sheath‐assisted design. To enhance the separation efficiency, a combination of the DEP focusing accompanied by weak sheath flows from both sides was proposed. This design achieved the highest sample separation yield in the outlets (as high as 98.7% for 15 μm) with a sample throughput of more than 4.2 μL/min. This study provides insights into the choice of an appropriate platform for any application in which the yield, purity, throughput, and portability must be considered.