Figure 3.

Additive micropatterning of magnetic particles. a) Particles micro-manipulated on curved surfaces (an eppindorf tube) wrapped by a PDMS membrane (left) and thick film (right). b) Particles can be manipulated at relatively large distances from the permanent magnet, and form repeatable particle networks. c) Controlled micro-manipulation of magnetic particles on coverslips above micromagnets under a rotating magnetic field. d) Diagram of dynamic and tunable interactivity of magnetic droplets with our taggable micromagnet array. The micromagnet array prevents particles from being manipulated by permanent magnet. Deprotecting particles by flexing the underlying array releases the particles for subsequent manipulation. e) Selective particle extraction via manipulation of the underlying magnetic matrix, allowing temporal subselection of magnetic particles from a single droplet. e) Formation of unique, bipolar magnetic droplets, which possess leading and retracting particle edges during magnetic droplet manipulation above micro-magnet matrix. Scale bar is 200 μm.