Systems and methods for minimization or elimination of diffusion effects in a microfluidic system

A system for collecting, from a continuous flow of two or more miscible fluids sequentially present in a first channel, one or more samples that are substantially free from contamination by other miscible fluids present in the first channel, said system comprising:

• the first channel containing at least two fluid slugs, wherein diffusion regions are formed between adjacent miscible fluids of adjacent slugs, the at least two fluid slugs including the diffusion regions moving along the first channel toward a second channel;
• the second channel intersecting the first channel;
• a collection region formed at a junction between the first channel and the second channel;
• and
• a fluid flow control system that controls the flow of fluid through each of the first channel and the second channel;
• wherein the fluid flow control system is configured to:
• flow the continuous flow of the two or more fluid slugs including the diffusion regions through the first channel for a predetermined time, wherein the predetermined time is sufficient to allow the diffused region of the at least two miscible fluids to pass the collection region of the first channel;
• collect a portion of a slug moving along the first channel, the collected portion of the slug substantially free from contamination by any miscible fluids, from the first channel into the second channel;
• stop the collection of one of the miscible fluids before a subsequent diffused region reaches the collection region of the first channel.