Three-dimensional porous scaffolds play a vital role in tissue engineering and regenerative medicine of functionalizing as biomimetic substrates to control cellular behavior. However, most techniques used to create scaffolds depend on stochastic processes which typically create scaffolds with coarse uncontrollable pores in terms of size, structure, and interconnectivity, dramatically restraining their usage in tissue regeneration. Microfluidic techniques have great potential to make inversed opal scaffolds, based on their ability to produce microbubbles or beads with a low polydispersity index (<5%). Inversed opal scaffolds are scaffolds with uniform pore size, architecture, pore structure, porosity, and interconnectivity.
In this work, we report a significant advancement for the preparation of monodispersed microbubbles, which are increasingly used and have become a key constituent in many advanced technologies. A new device comprising of two T-junctions containing coarse capillaries and operating in series was assembled. Microbubble generation was facilitated by using bovine serum albumin solution and nitrogen as the liquid and the gas phase, respectively. The effect of operating parameters such as gas pressure and liquid flow rate on
the size of the microbubbles generated were investigated for the two T-junction systems and the results were compared with a single T-junction process. The experimental results showed that microbubbles produced via the double T-junction setup were smaller at any given gas pressure for both liquid flow rates of 100 and 200 μm studied in this work. A predictive model is developed from the experimental data, and the number of T-junctions was incorporated into this scaling model. It was demonstrated that the diameter of the monodisperse microbubbles generated can be tailored using multiple T-junctions while the operating parameters such as gas pressure and liquid flow rates were kept constant. The stability of the microbubbles produced was also examined and indicated that microbubbles produced through the double T-junction were more stable. By using a coarse capillary of 200µm, the new device made by combining more than two T-junctions can bring the size of microbubbles down to a new limit; from 180µm to 20µm based on the same operating parameters as a single T-junction. This allows a wider range of pore sizes for scaffolds. In conclusion, the device developed in this work provides a simple straightforward one-step method to make monodispersed scaffolds in a different range of pore sizes, which particularly have great potential in the generation of inversed opal scaffolds.