Methods of manufacturing microfabricated substrates

A method of fabricating microfluidic devices, comprising:

• providing a first substrate having a first surface and a plurality of discrete groove networks disposed on the first surface, each of the plurality of discrete groove networks comprising at least two intersecting grooves;
• bonding a second substrate to the first surface of the first substrate, wherein the second substrate comprises a plurality of apertures disposed through it from a first surface of the second substrate to a second surface of the second substrate, said bonding comprising first applying a vacuum to said apertures and mating the second substrate with the first surface of the first substrate to create a bonded substrate wherein the intersecting grooves are sealed to produce a plurality of discrete channel networks, the plurality of apertures being positioned in the second substrate to be in fluid communication with the discrete channel networks;
• and
• separating a first portion of the bonded substrate containing at least a first discrete channel network from a second portion of the bonded substrate containing at least a second discrete channel network.