Microfluidic device with longitudinal and transverse liquid barriers for transverse flow mixing

A microfluidic device comprising a set of one or more microchannels, each microchannel comprising:

• a microchannel portion with a longitudinal liquid barrier extending longitudinally therein, thereby defining a first region and a second region in the microchannel portion;
• one or more first liquid passages, at the level of the longitudinal liquid barrier;
• a liquid inlet on a first side of the microchannel portion, configured to allow liquid to enter the first region;
• a liquid outlet on a second side of the microchannel portion, opposite to the first side, configured to allow liquid to leave the microchannel portion;
• a transverse liquid barrier arranged between the microchannel portion and the liquid outlet to hold liquid flowed from the liquid inlet in the first region, in operation;
• and
• one or more second liquid passages at the level of the transverse liquid barrier,
• the device further comprising a liquid pump configured to displace liquid through each microchannel portion of the set of one or more microchannels,
• wherein,
• the one or more first liquid passages are configured so as to allow, in operation, excess liquid in the first region to flow into the second region, transversally to the longitudinal liquid barrier, and the one or more second liquid passages are configured so as to allow, in operation, excess liquid in the microchannel portion to be discharged via the liquid outlet,
• and wherein the transverse liquid barrier is at a capillary distance from the longitudinal liquid barrier, so as to prompt excess liquid in the first region to flow into the second region rather than exit the microchannel portion via the one or more second liquid passages.

A method for controlling liquid in the microfluidic device, comprising:

• letting liquid enter a first region of a microchannel portion via a liquid inlet of the microfluidic device, wherein the letting liquid enter the first region is facilitated by a liquid pump, and wherein the microfluidic device comprises:
• the microchannel portion, the microchannel portion including a longitudinal liquid barrier extending longitudinally therein, thereby defining the first region and a second region in the microchannel portion;
• one or more first liquid passages, at the level of the longitudinal liquid barrier;
• the liquid inlet, configured to allow liquid to enter the first region;
• a liquid outlet, configured to allow liquid to leave the microchannel portion;
• a transverse liquid barrier arranged between the microchannel portion and the liquid outlet to hold liquid flowed from the liquid inlet in the first region, in operation;
• and
• one or more second liquid passages at the level of the transverse liquid barrier,
• the liquid pump configured to displace liquid through each microchannel portion of the set of one or more microchannels,
• wherein,
• the one or more first liquid passages are configured so as to allow, in operation, excess liquid in the first region to flow into the second region, transversally to the longitudinal liquid barrier, and
• the one or more second liquid passages are configured so as to allow, in operation, excess liquid in the microchannel portion to be discharged via the liquid outlet;
• letting liquid that has entered the first region fill the first region, the liquid being held by the transverse liquid barrier;
• letting excess liquid in the first region flow into the second region, transversally to the longitudinal liquid barrier, via the one or more first passages;
• letting excess liquid flow into the second region transversally to the longitudinal liquid barrier so as to fill the second region from a second side of the microchannel portion, near the liquid outlet, to a first side of the microchannel portion, near the liquid inlet;
• and
• letting excess liquid in the microchannel portion discharge into the liquid outlet, via the one or more second passages.