Microfluidic cuvettes and a network of multiplexed channels including such cuvettes. The channels operationally share a main output channel defining an output of the network. A microfluidic channel includes an inlet, a cuvette, and an outlet that is coupled into the main output channel. The network is configured to provide a difference in resistances, to the fluid, by the main output channel and by an individual outlet is sufficient to prevent cross-contamination of different cuvettes, thereby operably isolating individual channels from one another. An individual cuvette is adapted to substantially prevent the formation of air-bubbles as part of the fluid flow through the cuvette and, therefore, to be fully filled and fully emptied. A system and method for photometric measurements of multiple fluid samples employing such network of channels.