When you need to manipulate and direct fluids in small volumes, microfluidic systems are the technology of choice.

Used by engineers, chemists and biotechnologists in applications from enzymatic and DNA analysis to the detection of pathogens to clinical diagnostic testing and synthetic chemistry, the tiny systems once required a clean room to create and thousands of dollars to manufacture. They also required numerous iterations to achieve the required complexity.

Sometimes called a "Lab-on-a-Chip," the systems are now, through the work of USC researcher Krisna Bhargava, designed as 3D printable sets of building blocks which researchers can clip together in hours. The 1cc blocks can accomplish LOC functions like routing, mixing or analysis in three-dimensions. The researchers say a large share of the success in the fabrication process came as a result of recent advancements in high-resolution, 3D printing.

"You test your device and it never works the first time," says Bhargava, a graduate student in materials science at the Viterbi School of Engineering at USC. "If you've grown up to be an engineer or scientist, you've probably been influenced by LEGO at some point in your childhood. I think every scientist has a secret fantasy that whatever they're building will be as simple to assemble."

According to Bhargava, microfluidics might one day change the way fluidics are routed, combined, mixed, and analyzed by integrating a variety of functions into the tiny, complex devices.

Bhargava's three-dimensional modular components include common elements of microfluidic systems and are joined via a connector which hooks the separate components together. The micron-scale 3D printing technology which inspired Bhargava and his USC research team led Noah Malmstadt, a chemical engineering and materials science professor, and Bryant Thompson, a biomedical engineering graduate student, to design computer models for the eight modular fluidic and instrumentation components.

One such component, a helix, can be used to mix two fluid streams and is roughly the size of a standard, six-sided dice.

"What we've built looks more like a hobby breadboard. You can build a circuit on the cheap with your bare hands," Malmstadt says.

In just a few hours, the USC researchers built a test device. Essentially a track for the fluids to follow, it lets the team make adjustments in flow resistance or mix them as needed.

Malstadt says controlling the way fluids mix is a major concern due to the mechanics of fluid flow at very small dimensions. He says it's all about developing ways to create twists and turns in the channels to improve mixing. He adds that the team hopes an open community will one day share designs via an open-source database.

Their paper, Discrete Elements for 3-D Microfluidics, was published in Proceedings of the National Academy of Sciences of the United States of America on September 22.