Using LEGO bricks for microfluidics

Melanie Gonick/MIT

RESEARCHERS at MIT have simplified the process of creating microfluidics prototypes by building them out of LEGO bricks.

Creating a traditional lab-on-a-chip for microfluidics operations is an often painstaking task, which prompted Crystal Owens and Anastasios John Hart to turn to LEGO bricks as a method of constructing a microfluidics prototype. LEGO bricks are ideal because they are around the same size as a microfluidic chip. The bricks are also manufactured consistently throughout the world, ensuring that any two bricks can easily click into place.

Microfluidic devices usually contain all the necessary components on one chip, but the researchers wanted to make microfluidics modular so that each component could be housed within an individual LEGO brick. This means the bricks can be mixed and matched into the combination required rather than building unique chips each time.

"Because LEGOs are so inexpensive, widely accessible, and consistent in their size and repeatability of mounting, disassembly, and assembly, we asked whether LEGO bricks could be a way to create a toolkit of microfluidic or fluidic bricks," said Hart, associate professor of mechanical engineering at MIT.

The team used micromilling, a common technique for drilling submillimetre features into materials, to create small channels within the bricks. The channels were designed so that the outlet of one block lined up with the inlet of another, and the walls were then sealed with an adhesive.

By drilling a 500 µm wide channel, Owens, a graduate student in MIT's Department of Mechanical Engineering, was able to create fluidic bricks for different purposes. A LEGO brick can successfully transport small amounts of liquid, making it a functional flow resistor. Fluids can be mixed within a brick by creating a Y-shaped channel and feeding the two liquids through the arms of the Y. A drop generator can be created using a T-shaped channel which causes the fluid to exit the brick as droplets.

Once combined, the bricks can be used for biological operations such as sorting cells, mixing fluids, and filtering out molecules of interest into droplets.

The most challenging aspect of the work was ensuring that no leaks occurred once the bricks were connected. Owens solved this problem by placing a small O-ring around each inlet and outlet of the brick. When connected to another brick, the O-ring is compressed and creates a fluid seal between bricks.

There are still some challenges around using LEGO, mainly that micromilling produces channels that are tens of microns wide, where smaller channels are often required by microfluidic processes.

The thermoplastic of the LEGO bricks is also a problem as it cannot withstand exposure to certain chemicals.

"We've been experimenting with different coatings we could put on the surface to make LEGO bricks, as they are, compatible with different fluids," said Owens, adding: "LEGO-like bricks could also be made out of other materials, such as polymers with high temperature stability and chemical resistance."

The team is currently designing a website that will provide instructions on how others can create their own fluidic LEGO bricks using standard LEGO pieces.