Microfluidics for fabrication of Biomaterials

Microfluidics for generation of microparticles and microcapsules through chemical gelation

Microparticles and microcapsules have numerous applications in the fields of drug delivery, tissue engineering, photonics, disease diagnosis, etc. to name a few. Microfluidics offers an attractive route to generation of these entities due to the precise control it can provide over size, composition, and shape. In this work we have employed droplet coalescence as a method to achieve chemical gelation and generate alginate microcapsules with an oil core. We have demonstrated generation of multi-core microcapsules as well. The developed method has major advantages in terms of having an intact core, continuous operation, and minimal damage to encapsulate entities.

Publications:

Eqbal, M. D., & Gundabala, V. (2017). Controlled fabrication of multi-core alginate microcapsules. Journal of colloid and interface science, 507, 27-34.

Fabrication of microparticles in the presence of electric fields

In this work, we have developed a 3D PDMS-glass hybrid device for generation of alginate mciroparticles and microcapsules in the presence of electric fields. Here we demonstrated reduction in particle size owing to the application of electric fields and also achieved low polydispersity compared to external Electrohydrodynamic atomization methods. Interaction between a droplet and a stationaery liquid-liquid interface, typically studied in external systems, is exploited in this microfluidic setup to achieve chemical gelation.

In another related work, we coupled electric fields with photopolymerization to fabricate PEGDA (polyethylene glycol diacrylate) microparticles and hydrogels. We have shown that such coupling can provide additional control over size, uniformity, and morphology. The rapid solidification afforded through UV polymerization, the particle size tuning possible through electric field application, and the control provided by microfluidics is a robust combination suitable for fabrication of future biomaterials.

Publications:

Eqbal, M. D., & Gundabala, V. (2020). On-chip generation of microcapsules in the presence of applied electric fields. Journal of Micromechanics and Microengineering, 30(4), 045002.

Pullagura, B. K., Amarapalli, S., & Gundabala, V. (2020). Coupling electrohydrodynamics with photopolymerization for microfluidics-based generation of polyethylene glycol diacrylate (PEGDA) microparticles and hydrogels. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 125586.

Generation of polymer microfibers using microfluidics

Polymer microfibers have applications in various fields such as tissue engineering, electronics, textiles, etc. Existing production techniques such as drawing, wet spinning, and electrospinning suffer from lack of control over the size, morphology, and composition. Microfluidics based production techniques offer great versatility in terms of control. Despite the versatility that microfluidics provides, one aspect that has received little attention is controlling the extent of coiling of the generated fiber. In this work, we have developed a microfluidics-based solvent removal technique for the complete on-chip generation of poly(ethylene oxide) (PEO) fibers. Using complementary flows, we show the ability of the technique to control the extent of coiling of the generated fiber. This allows a facile transition from nonwoven fiber generation mode to single-fiber generation mode, primarily through variation of complementary flow rates within the same device. We expect that this work will broaden the scope of microfluidics as a tool to generate microfibers for a wider range of applications than the existing techniques.

In another work, we develop bacterial and mammalian cell encapsulated core-shell microfibers for different biological applications. 

Publications:

Pullagura, B. K., & Gundabala, V. (2020). Microfluidics-Based On-Demand Generation of Nonwoven and Single Polymer Microfibers. Langmuir, 36(5), 1227-1234.