Real-time detection, control, and sorting of microfluidic droplets.

We report the design and implementation of capacitive detection and control of microfluidic droplets in microfluidic devices. Integrated microfluidic chip(s) with detectioncontrol circuit enables us to monitor in situ the individual volume of droplets, ranging from nanoliter to picoliter, velocity and even composition, with an operation frequency of several kilohertz. Through electronic feedback, we are able to easily count, sort, and direct the microfluidic droplets. Potential applications of this approach can be employed in the areas of biomicrofluidic processing, microchemical reactions as well as digital microfluidics.