Abstract

Droplet Emulsion Generation based on Electrokinetics: Digital PCR and Cell Encapsulation

Hsueh-Chia Chang, Bayer Professor of Engineering / Director, University of Notre Dame

We report a new microdroplet generation technology that uses AC electric field rather than hydrodynamic shear to generate droplets. Intricate flow-rate tuning of both phases is hence unnecessary and massive parallelization is now possible because of the absence of hydrodynamic cross-talk.   The bulky and expensive precision micropump is replaced by a simple and miniature AC source that can be driven by a battery.  With a less viscous oil phase and a properly tuned AC frequency, we are able to eliminate electro-coalescence and Rayleigh fission.  Monodispersed droplets with CV less than 3% and with a size range from 10 to 100 microns can be generated at a high throughput of nearly 1000 Hz per nozzle.  Moreover, the size of the droplets can be easily adjusted by simply tuning the voltage or the frequency.  One hundred to one million droplets and, with parallelization,  more than 1 billion droplets can be generated in 30 minutes.  This large range allows high-dynamic range digital PCR and conformal cell encapsulation.