Microfluidic devices and systems, and methods for operating microfluidic devices and systems

A microfluidic system comprising:

• a. a microfluidic device comprising a substrate having at least a first fluid inlet/outlet system, at least a second fluid inlet/outlet system, and a fluidic network between the first fluid inlet/outlet system and the second fluid inlet/outlet system and in fluid communication with the first fluid inlet/outlet system and the second fluid inlet/outlet system;
• b. a fluid injection system comprising:
• i) at least a first injector connected to the first fluid inlet/outlet system for forcing fluid through the microfluidic device in a forward direction, from the first injector to the first fluid inlet/outlet system and through the microfluidic device from the first fluid inlet/outlet system to the second fluid inlet/outlet system via the fluidic network, and ii) at least a second injector connected to the second fluid inlet/outlet system for forcing fluid through the microfluidic device in a reverse direction, from the second injector to the second fluid inlet/outlet system and through the microfluidic device from the second fluid inlet/outlet system to the first fluid inlet/outlet system via the fluidic network;
• c. a back-pressure regulator connected to the first fluid inlet/outlet system and the second fluid inlet/outlet system, wherein the back-pressure regulator is configured to apply back-pressure to the fluidic network to facilitate operation of the microfluidic system at high pressure;
• and
• d. an optical investigation system for viewing at least a portion of the fluidic network.