A fluid analyzer for analysis of analyte bearing fluids includes an optical source and an optical transducer defining a beam path of an optical beam; a fluid flow cell with a fluid channel, wherein an interrogation region is defined in which the optical beam interacts with the fluids resulting in transducer output signals; and a controller configured and operative to control operation of the fluid analyzer. In one example the fluid analyzer is controlled to (1) combine a third fluid with the first or second fluid, (2) conduct the first fluid and second fluid through the interrogation region in first and second intervals respectively, (3) measure the transducer output signals during the first and second time intervals, and (4) determine, from the transducer output signals measurement, values of the first and second fluids and an indication of a physical property of the first fluid.

The invention provides methods for assessing one or more predetermined characteristics or properties of a microfluidic droplet within a microfluidic channel, and regulating one or more fluid flow rates within that channel to selectively alter the predetermined microdroplet characteristic or property using a feedback control.

A microfluidic cartridge for assaying an analyte comprises one or more test channels, each having a lumen; one or more reference solution channels in fluid communication with the test channels; one or more sample channels in fluid communication with the test channels; one or more sensors at least partially exposed in the lumen of the test channels; and a processor coupled to the one or more sensors for measuring properties of the analyte to determine at least one of an identity, concentration, dose, and dosage of the analyte.

The invention provides methods for assessing one or more predetermined characteristics or properties of a microfluidic droplet within a microfluidic channel, and regulating one or more fluid flow rates within that channel to selectively alter the predetermined microdroplet characteristic or property using a feedback control.

The invention provides methods for assessing one or more predetermined characteristics or properties of a microfluidic droplet within a microfluidic channel, and regulating one or more fluid flow rates within that channel to selectively alter the predetermined microdroplet characteristic or property using a feedback control.