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.