On-Demand Droplet Routing and Splitting Using Independently Addressable Interdigitated Electrodes.

Droplet microfluidics enables precise manipulation of picoliter-to-nanoliter-scale droplets and supports key operations such as merging, splitting, sorting, and trapping, facilitating controlled handling of minute fluid volumes. These capabilities have significantly advanced high-throughput drug discovery, single-cell analysis, molecular diagnostics, and synthetic biology. Among these operations, droplet splitting is particularly important for multi-step biochemical assays and parallel processing. Splitting strategies can be broadly categorized as passive, relying on channel geometry or microstructures, or active, employing external stimuli such as thermal, magnetic, acoustic, or electric fields. Electric-field-based methods are especially attractive due to their rapid response and tunability; however, many reported systems require relatively high operating voltages. Here, we present a low-voltage microfluidic platform that integrates tilted interdigitated electrodes (IDEs) with an asymmetric Y-junction to enable electrically tunable droplet splitting and sorting within a single device architecture. Two independently addressable tilted IDE arrays generate localized electric-field gradients that induce dielectrophoretic droplet deflection at moderate voltages. By adjusting the applied voltage amplitude and selectively activating the electrode arrays, droplets can be dynamically routed into designated outlets or deterministically split in real time, providing adaptable electrohydrodynamic control with minimal structural complexity.