To make particles flow more efficiently, put an obstacle in their way
Nowadays, they automate research by using microfluidic chips the size of postage stamps. In these tiny devices, millions of microscopic particles are captured in droplets of water, each droplet serving as the “test tube” for a single experiment. The chip funnels these many droplets, one at a time, through a tiny channel where a laser probes each passing droplet to record thousands of experimental results each second.
These chips are used for such things as testing new antibiotics, screening drug compounds, sequencing the DNA and RNA of single cells, and otherwise speeding up the pace of scientific discovery.
The problem, however, is that droplets racing toward the narrow end of the funnel can become congested and collide, breaking up in a way that can foul experiments, just like shattering test tubes in the old days. “It’s a traffic problem, like several lanes of cars trying to squeeze through a tollbooth,” said Sindy Tang, an associate professor of mechanical engineering at Stanford School of Engineering.
But her lab recently showed how it was possible to make microfluidic experiments far more efficient by putting near the base of the funnel tiny “traffic circles” that cause droplets to line up in an orderly fashion so they can zoom through the system with far fewer collisions. (see video).
