Integrating EWOD with Surface Ratchets for Active Droplet Transport and Sorting

Combining surface ratchets and electrowetting on dielectric (EWOD) produces novel microfluidic systems that achieve passive droplet transport by vibration along microscopically-rough surfaces and active droplet sorting by electric signals. The super-hydrophobic surface ratchet and EWOD plate sandwich a droplet; when vibrated the device adopts passive droplet transportation via the surface ratchet. The EWOD technology is utilized at particular junctions to produce several droplet specific control functions, including the combination of a new ratchet design with an EWOD plate to develop a switch (serving the same purpose as a switch in train tracks) that sorts 10 mul droplets at a junction.