An intelligent droplet sorter using optimized liquid-metal electrodes for droplet sorting under a low voltage

Abstract

The sorting of target droplets is an essential function in droplet microfluidics. Previous dielectrophoresis-based droplet sorters were often designed based on experience and required ultrahigh driving voltages of more than 1 kV. In this study, an intelligent droplet sorter (IDS) using optimized liquid-metal electrodes was developed for droplet sorting at a low voltage of 80 V. To explore the optimal structure, we carried out numerical simulations to optimize the dimensions, shapes, and layouts of the electrodes. The optimized IDS with a square active electrode and two pairs of shielding triangular electrodes was obtained based on the normalized dielectrophoresis force ξ and comprehensive efficiency η. Subsequently, the optimized electrodes made of liquid metal were used to deflect droplets under a low driving voltage of 80 V. Finally, we integrated our IDS with an intelligent droplet detection system and successfully applied the system for the sorting of target-encapsulated and empty droplets with encapsulation and collection efficiencies of over 90 %. Our IDS offers the advantages of low voltage, easy fabrication, and excellent performance and thus shows significant potential in sorting target droplets.