APPARATUS AND METHODS FOR PREPARATION OF SUBSTANTIALLY UNIFORM EMULSIONS CONTAINING A PARTICLE

Methods and systems for forming water-in-oil emulsions are described. For example, an apparatus is described which includes: a first compartment containing a plurality of particles dispersed in an aqueous phase; a second compartment containing an oil phase; a porous layer separating the first and second compartments; and a device for applying pressure to the first compartment. A method is described which includes: moving an oil phase relative to a surface of a porous layer while simultaneously forcing an aqueous composition comprising particles through the porous layer and into the flowing dispersion medium thereby forming droplets of the aqueous composition containing particles dispersed in the oil phase. The aqueous composition can include one or more nucleic acid templates and reagents for amplifying the nucleic acids such as PCR reagents. A porous partition is described comprising a first and second major surfaces and at least two straight through pores comprising a cross sectional shape selected from a polygon, an oval, an oblong, a dumbbell, a bowtie and irregular shapes thereof. Aqueous droplets containing an oligonucleotide attached to a particle and reagents can be used as a microreactor for nucleic acid amplification.