Magnetically maneuverable three-dimensional digital microfluidic manipulation of magnetic droplets for biochemical applications

We propose a three-dimensional (3D) manipulation strategy of magnetic droplets by maneuvering magnetic fields for biochemical applications. To ascertain the feasibility of the 3D manipulation of magnetic droplets, we examine the horizontal and vertical transport of the droplets by the handling of a permanent magnet. The maximum magnet speed (∼35 mm s⁻¹) that allows for stable droplet transport without any extraction of magnetic particles can be determined through magnetic droplet rotation tests. Additionally, particle extraction from magnetic droplets can be facilitated by introducing a chemically modified surface energy trap. Finally, to demonstrate the applicability of the proposed 3D manipulation strategy to biochemical applications, we examine the transporting and merging of two magnetic droplets containing chemical reactants and subsequent particle extraction from the reacted droplet. The employment of the magnetically steerable 3D manipulation strategy can provide utility and flexibility in the development of 3D digital microfluidics platforms for myriad biochemical (or biomedical) applications. (author)