Characterization of microdroplets using optofluidic signals.

We develop a simple method to determine the microdroplet features in a microfluidic chip fabricated by conventional soft lithography. Different sizes of microdroplets are generated through a typical microfluidic T-junction by adjusting the flow rates of the two immiscible liquids. Droplet size and content can be determined by monitoring the optofluidic signals reflected at the fluid-polydimethylsiloxane (PDMS) interface. The demonstrated droplet characterization system can be readily integrated with other microfluidic networks, making it promising for biochemical and biosensing applications.