A micro-rheological method for determination of blood type.

The measurement of time and distance can be used for determining agglutination in small (nL) samples of liquid. We demonstrate the use of this new scheme of detection in typing and subtyping blood in a simple microfluidic system that monitors the speed of flow of microdroplets. The system (i) accepts small samples of liquids deposited directly onto the chip, (ii) forms droplets on demand from these samples, (iii) merges the droplets, and (iv) measures their speed in a microchannel.

Discontinuous transition in a laminar fluid flow: a change of flow topology inside a droplet moving in a micron-size channel.

Even at moderate values of Reynolds number [e.g., Re=O(1)] a curved interface between liquids can induce an abrupt transition between topologically different configurations of laminar flow.

Speed of flow of individual droplets in microfluidic channels as a function of the capillary number, volume of droplets and contrast of viscosities.

Droplet microfluidic techniques offer an attractive compromise between the throughput (of i.e. reactions per second) and the number of input/output controls needed to control them.

Effects of unsteadiness of the rates of flow on the dynamics of formation of droplets in microfluidic systems.

Oscillations of the input rates of flow have a significant impact on the dynamics of formation of droplets in microfluidic systems and on the quality of generated emulsions.