3D nanoprinting technique enables faster and cheaper microfluidic devices

A team of engineers from the University of Maryland (UMD) have developed the world’s smallest 3D printed fluid circuit element using a new nanoprinting technique. The 3D printed fluid circuit diode, which measures just one-tenth of the width of a human hair, helps liquids flow in a single direction in microfluidic devices and could be used in implantable devices to release drugs into the body in a controlled manner.

Scientists around the globe have been exploring and advancing 3D nanoprinting processes to create tiny medical devices and organ-on-a-chip systems. Up until now, however, the technology has been somewhat limited in terms of scale because of challenges of printing microfluidic devices with no leakages and extremely precise fluid control. In other words, while the devices could be made on a small scale, it was too expensive and too challenging to print features at a scale as tiny as the one recently demonstrated.

“This really put a limit on how small your device could be,” said Andrew  Lamont, a bioengineering student who developed the approach and led the tests as part of his doctoral research. “After all, the microfluidic circuitry in your microrobot can’t be larger than the robot itself.”

The breakthrough microfluidic helical coil spring diode from UMD was 3D printed using an in situ direct laser writing process (inDLW) that is not tethered by the same cost and complexity challenges as existing systems. The innovative strategy was developed by Ryan Sochol, an assistant professor in mechanical engineering and bioengineering at UMD and graduate students Andrew Lamont and Abdullah Alsharhan.

The novel technique uses a process called sol-gel to fully achor the diode to the walls of a micro-scale channel 3D printed from a common polymer material. The tiny diode could be printed directly inside the channel, from the top down, using a layer-by-layer method. This technique, the engineers explain, results in a “fully sealed, 3D microfluidic diode” that is both faster to produce and significantly cheaper than an equivalent part made using another approach.

The microfluidic diode was further improved by reshaping the microchannel walls to have increased outward tapering, which ensured a stronger seal. Having a strong seal is essential as it protects the circuit from contamination and ensures that the fluid in the device is only released when it is intended.

“Where previous methods required researchers to sacrifice time and cost to build similar components, our approach allows us to essentially have our cake and eat it too,” Sochol explained. “Now, researchers can 3D nanoprint complex fluidic systems faster, cheaper, and with less labor than ever before.”

He added: “Just as shrinking electric circuits revolutionized the field of electronics, the ability to dramatically reduce the size of 3D printed microfluidic circuitry sets the stage for a new era in fields like pharmaceutical screening, medical diagnostics, and microrobotics.”

The full study was recently published in the open-access journal Scientific Reports.