Programmable tracking pressure regulator for control of higher pressures in microfluidic circuits

A system for delivering a liquid sample to a point of use which comprises:

• a storage volume in fluid communication with a gas,
• an inlet capillary conduit for receiving a liquid sample in fluid communication with the storage volume,
• an outlet capillary conduit for receiving a liquid sample in fluid communication with the storage volume,
• the storage volume being dimensioned to form a meniscus on a capillary liquid stream passing within the storage volume,
• a capillary gate in fluid communication with the outlet capillary conduit, and in fluid communication with a gas, and being dimensioned to permit liquid to flow through the capillary gate between the outlet capillary conduit and a drain capillary conduit,
• and a tracking pressure regulator for controlling gas pressure in the storage volume, the tracking pressure regulator comprising:
• a controller;
• a pressure transducer in communication with the controller, the pressure transducer being positioned to measure differential pressure between the gas and first and second fluid streams, the transducer adapted to send a signal to the controller indicative of that differential;
• a valve through which the gas flows, the valve being responsive to the controller, whereby the flow of the gas out of the valve and into the storage volume is regulated based upon the differential.

A method of controlling pressure differences between connected pressure control nodes, comprising:

• providing a sealed housing containing a first and second measured fluid stream and a reference fluid stream;
• sensing the differential pressure between the first measured fluid stream and the reference fluid stream with a first pressure transducer;
• regulating the flow of the first measured fluid stream based upon the differential;
• sensing the differential pressure between the second measured fluid stream and the reference fluid stream with a second pressure transducer;
• and
• regulating the flow of the second measured fluid stream based upon the differential.