Achieving continuous focusing of particles and blood cells via AC insulator-based dielectrophoresis

Insulator-based dielectrophoresis (iDEP) technology manipulates particles by creating a non-uniform electric field using insulating microchannel structures. It offers advantages such as high operability and electrode-free fabrication. However, the fluid driving and construction of non-uniform electric fields based on iDEP currently mainly relied on direct current (DC), which can easily lead to water electrolysis and the generation of a large amount of Joule heat. In this study, we used two metal tubes as electrodes to apply the AC and inlet/outlet to provide stable liquid flow based on the syringe pump, ensuring stable flow and achieving the focusing of particles and blood cells. Through numerical simulation, a ratchet structure with semicircular tooth surfaces was selected. This structure provides a more uniform distribution of high-field strength regions and can withstand higher flow rates. Subsequently, experiments were conducted to determine the focusing characteristics of particles under different conditions within this chip. Cell focusing throughout improved by nearly 3 times of magnitude compared to that of similar iDEP focusing techniques. Finally, the visualization experiment realized the defined morphology focusing of blood cells, and the optimal focusing ratio reached 7.27, and the focusing characteristics of blood cells were studied. This study is expected to promote the application of dielectrophoresis technology in clinical, biological and other aspects.