To make particles flow more efficiently, put an obstacle in their way

A bottleneck limits the effectiveness of microfluidic chips. Reaction-containing droplets can collide, break up, and foul experiments. 'It's a traffic problem, like several lanes of cars trying to squeeze through a tollbooth,' says a mechanical engineering professor. Placing 'traffic circles' in the flow path causes droplets to line up in an orderly fashion so they can zoom through the system with far fewer collisions.

from Latest Science News -- ScienceDaily https://www.sciencedaily.com/releases/2021/05/210524110224.htm