Integrated microfluidic systems for droplet detection and sorting

Abstract

Microdroplet based microfluidic systems have gained a lot of attention during the last decades due to enhanced analytical performance, low cost and high-throughput. One of the fundamental requirements of a droplet based system is detection of droplets. Capacitive sensing of droplets have been used for droplet detection, however they lack the required sensitivity for droplet content detection. Here a portable, low cost, scalable and highly sensitive droplet content detection system is demonstrated using coplanar electrodes. The designed microfluidic system enables droplet content modification on the run. While changing droplet content, i.e., dielectric content, capacitive signal amplitude is measured. The system resolves 3 unit of dielectric permittivity. 5% material change in droplet is detected. Following droplet content detection, sorting of laden droplets enables further experimentation with material of interest in the droplet. Dielectrophoresis is a commonly used method for droplet sorting. Dielectrophoretic sorting of droplets is demonstrated using two dimensional and there dimensional electrodes. Low cost and portable electronic components are integrated with microfluidic devices for droplet content detection and sorting using microfabricated electrodes. The cost and signal to noise ratio of the system are aimed to be decreased by implementing detection and sorting system on a printed circuit board. Sensing and sorting electrodes are fabricated and all of the electronic components are placed on a printed circuit board. Microchannels are reversibly placed over electrodes, therefore the platform becomes reusable. This feature of the system enables various experimentation using microdroplets on the same base platform. This approach will lead to microfluidic systems that are programmable and easy-to-use by means of off-the-shelf and low cost electronic components.