Integrated droplet microfluidic device for magnetic particles handling: Application to DNA size selection in NGS libraries preparation

We present an innovative droplet microfluidic device based on integrated soft-magnetic structures allowing extraction, redispersion and depletion processes of magnetic particles. Following a numerically-assisted conception, the device was at first fabricated and experimentally characterized, showing reliable and efficient magnetic particles extraction with a low carryover of the initial matrix (< 3.5%), in a broad range of dispersed phase viscosities (between 1 and 15 mPa.s) and particles loads (between 0.1 mu g and 1.5 mu g). Its functionalities were successfully exploited to perform DNA size selection processes for NGS libraries preparation. The device achieved final concentrations and size distributions comparable with conventional methods, demonstrating compatibility with downstream sequencing and providing improvements in automation, throughput and workflow simplification. Finally, this device represents a universal solution for high throughput multi-steps magnetic solid phase extraction workflows in a wide range of applications, e.g. immunoassays, nucleic acids and proteins purification, and sample preparation.