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Tiny Traffic Circles can Act as a Herding Dog for Particles in Microfluidic Experiments

  • Uncategorized
  • Aug 06, 2021

Today the automated research is done with microfluidic chips which are roughly the size of a postage stamp. These tiny devices consists of a millions of microscopic particles that are captured in drops of water, and each drop serves as a test tube for a single experiment. Droplets passes through a small channel where a laser examines each passing droplet to record thousands of experimental results every second. The problem, however, is that the droplets running towards the narrow end of the funnel can get clogged and collide, which can mess up the experiments. “It's a traffic problem, like multiple lanes of cars, all trying to pass through a toll booth”, said Sindy Tang, an associate professor of mechanical engineering at Stanford School of Engineering. But her lab recently demonstrated how it was possible to make microfluidics experiments much more efficient. This was demonstrated by placing tiny traffic circles near the bottom of the funnel that neatly arrange the droplets so that they can zoom through the system with far lesser collisions. In an article published in the Proceedings of the National Academy of Sciences detailing the results, she and her team, led by former Stanford engineering student Alison Bick, found that droplet fractures were a thousand times less common in the traffic circle system. Researchers found that the precise location of the traffic circles or the roundabouts was the decisive variable: roundabouts that were too far from the funnel exit do not affect the breakup but roundabouts that were near the exit end up causing more collisions and breakdowns. “There is an optimal point in the placing of roundabouts that minimizes the reduction of breakup in the droplet flow,” said Tang. Using properly placed roundabouts could result in a 300 percent increase in the experimental efficiency.

This technology could lead to a faster way to detect drugs, as well as many other benefits. For an instance, 3D printers work in a similar way as they force droplets of plastic or some other emulsion through a fine nozzle at high speed to gradually build up structures layer by layer. So this technology can prove to be groundbreaking in 3D printing. This discovery has led to applications that extend beyond research to other systems involving interactions between many bodies of similar size from a group of biological cells to a wide variety of people. This work has been supported by the National Science Foundation as well.