Chemical Engineers Get Unbalanced

Jonathan Strickland


As a kid, I knew shapes were important. I had toys, books and even shows like Sesame Street teaching me about shapes. Somewhere along the line, I stopped getting the message. But thankfully the chemical engineers at MIT had greater focus than I did. They've discovered a way to exploit the asymmetrical shape of tiny particles to make those particles behave in a specific way.

This really blows my mind -- the engineers designed these particles so that their shapes would cause them to follow predetermined pathways in microfluidic environments. This could lead to revolutionary developments in medical equipment, and here's why.

Current hardware for some types of medical analysis funnels particles through microchannels for analysis. But to keep everything orderly, the equipment needs extra instrumentation to make sure the particles travel in single file. More instrumentation means larger devices, limiting the portability and utility. But by exploiting this asymmetrical nature of particles, engineers might be able to design chips with microchannels in which the particles need no outside guidance to keep things nice and tidy.

That could mean a new wave of medical devices that can be used in the field to help detect serious illnesses like cancer, increasing the chances of survival for millions of people. The particles, designed in the lab, will change as they come into contact with proteins or DNA that indicate the presence of cancer.

What's so special about asymmetry? It all has to do with the flow of particles down these microchannels. Each particle looks like a tiny dumbbell with one side larger than the other. As the particle travels down the channel, the larger side creates drag and the dumbbell travels in a slanted orientation down the channel. This means it also begins to move closer to one side of the channel.

But as it gets close to the channel's side, the fluid dynamics change. Perturbations caused by the particle reflect off the channel's wall and hit the particle. This makes the particle change its orientation, slanting in the opposite direction and moving it toward the other wall of the channel. With the right amount of asymmetry, the particle will travel pretty much down the center of the channel.

How incredible is it that a new generation of medical devices could be more effective simply because engineers learned a little more about how shapes behave in a specific environment? Looks like it's time for me to watch a little more Sesame Street.