Methods for the filtration of small-volume heterogeneous suspensions in a digital microfluidic device

A digital microfluidics based method for filtration of heterogeneous suspensions, comprising:

• a) positioning a porous material between a bottom plate and a top plate in a digital microfluidic device, the porous material having a pre-selected porosity to prevent particles larger than a pre-selected size to pass through while allowing passage therethrough of particles being smaller than said pre-selected size;
• b) dispensing a droplet containing particles of different sizes onto an electrode array located on the bottom plate and actuating the electrode array in such a way as to drive the droplet through the porous material from a first side to a second side of the porous material such that the particles smaller than the pre-selected size pass through the porous material to form a filtered droplet while the particles larger than the pre-selected size are trapped in the porous material or on a surface of the porous material on the first side;
• c) actuating the electrode array for displacing the filtered droplet away from the porous material to await further processing;
• d) dispensing a droplet of resuspension buffer onto the electrode array on the second side of the porous material and actuating the electrode array so as to drive the droplet of resuspension buffer through the porous material from the second side to the first side of the porous material so that the larger trapped particles are freed from the porous material and suspended into the droplet of resuspension buffer on the first side of the porous material;
• and
• e) actuating the electrode array for displacing the droplet of resuspension buffer away from the porous material to optionally await further processing,
• wherein the porous material is an elongated strip of porous material having a length defined by elongated opposed sides and opposed ends,
• wherein the method comprises preventing liquid exiting at least one of the opposed ends by providing the at least one of the opposed ends with a non-porous hydrophobic material embedded therein and, the elongated opposed sides being devoid of the non-porous hydrophobic material, and
• wherein the non-porous hydrophobic material has hydrophobicity higher than that of said porous material, and the non-porous hydrophobic material is anchoring the strip of porous material to the top and/or bottom plate.