What Is Microfluidics?
Microfluidics involves manipulating fluid flow within channels that typically range from 1 micrometer to 1 millimeter in width. In these microscale environments, surface tension and viscosity play more significant roles than gravity and inertial forces, which are predominant in larger-scale fluid mechanics.
Microfluidic channels are created using semiconductor microfabrication technology. This miniaturization allows for reduced reagent usage and improved reaction efficiency by leveraging the unique properties of micro-spaces.
Uses of Microfluidics
Microfluidic devices find applications in various fields, combining engineering technologies like miniaturization, reduced reaction temperature energy, electrochemistry in micro-spaces, sensor integration, and automation. These devices facilitate faster and more efficient chemical reactions due to the significant effect of molecular diffusion in a large specific surface area, especially when two fluids are mixed.
Microfluidics is crucial in producing monodisperse droplets for pharmaceutical and cosmetic applications, encapsulating cells in droplets for culture in tiny test tubes or petri dishes, and performing high-throughput analysis. This analysis is often enhanced by integrating cell-encapsulated droplets with Fluorescence-Activated Cell Sorting (FACS) and sequencers.
Droplet Creation Using Microfluidics
Diverse microfluidic channel designs have been developed for specific applications, using materials like PDMS, glass, and plastic. Droplet formation typically occurs in cross-shaped microfluidic channels. Here, two immiscible fluids – the dispersed and continuous phases – are pumped into the channels.
At the junction, the continuous phase flows through the upper and lower channels, while the droplet-forming solution is introduced from the side. Micro-droplets are created by the shear force at the junction, effectively pinching and cutting the solution in the droplet phase.
The size of these droplets can be controlled by the flow rate ratio of the two fluids. While increasing the flow rates can boost droplet production, excessively high velocities may prevent proper droplet formation and result in jet flow instead.