More than a Drop in the Bucket

When it comes to the management of microdroplets in applications like drug delivery and chemical engineering, precision is paramount. The timing and volume of droplets in medical scenarios, for instance, requires a very specific balance that is not always easy to achieve.

In recent microfluidic research, high-resolution imaging systems with advanced processing capabilities have been used effectively to analyze droplet behavior. But these processes are time-consuming and require the use of expensive imaging facilities. Detecting droplet size is especially arduous and relies on a volume fraction method involving manual measurements of magnetic fields and flow velocities.

Khan et al. demonstrated a novel pressure fluctuation-based method to produce uniform, micron-sized droplets in a co-flow geometry using Multiphysics and MATLAB software. The approach appears to accurately reveal droplet sizes based on pressure fluctuations exerted on outer wall channels and dispersed fluid flow rates.

“The pressure versus time signal measured on the wall near to the exit of a micro-channel and its Fourier transform provide the information of droplet formation frequency,” said author Sunil Kumar Thamida.

The researchers examined how their pressure fluctuation-based method can determine droplet sizes. They also factored in parameters such as capillary numbers and flow rate, density, and viscosity ratios. In comparison to the conventional method, theirs yielded similar findings. It also promises to be instructive in examining droplet deviations.

“We found that the droplet size calculated with the pressure fluctuation method closely matched with the volume fraction method,” said Thamida. “The proposed approach is beneficial in the field of droplet microfluidics, emulsions, and encapsulation studies.”

Source: “Numerical simulations to determine the size of micro droplets without visualization by measuring pressure fluctuations,” by Babajan Bakthar Khan, Sunil Kumar Thamida, and Anil B. Vir, International Journal of Fluid Engineering (2024). The article can be accessed at https://doi.org/10.1063/5.0216548 .