On-chip generation of microcapsules in the presence of applied electric fields

Abstract

Here, we present a complete on-chip technique for the generation of microparticles and microcapsules through chemical gelation in the presence of electric fields. A hybrid glass-PDMS (polydimethylsiloxane) microfluidic device acts as a single platform for application of electric fields to generate single/double emulsions, followed by their chemical gelation using an interface (liquid–liquid) based approach. Using this method, we have generated uniformly sized alginate microparticles and alginate microcapsules with a liquid core. We identify the flow rates required for establishing a stable liquid–liquid interface and characterize the effect of electric fields on droplet sizes of various systems. We also demonstrate significant size reduction of the particles compared to non-EHD (electrohydrodynamics) approaches and low polydispersity compared to existing external EHD-based methods. It is expected that the technique presented here will open up new strategies for combining the control provided by microfluidics with the size reduction possible with EHD, for a host of biomaterials.