A microfluidic method comprising: taking a microfluidic device comprising a substrate, and a plurality of microvolumes at least partially defined by the substrate, each microvolume comprising a first submicrovolume and a second submicrovolume in fluid communication with the first submicrovolume; adding fluids to the first submicrovolumes; and applying a centrifugal force to the device to cause a same volume of fluid to be transported to the second microvolumes from the first submicrovolumes.