Micro 3D Printing for Micro-Optofluidics

Lorena Saitta, PhD in the Polymers and Composites Lab at the University of Catania (responsible Professor Gianluca Cicala) in collaboration with the Microfluidic Lab (responsible Professor Maide Bucolo) and Inorganic Chemistry Lab (Professor Maria Elena Fragalà), was working on designing micro-optofluidic devices suitable for the optical investigation of two-phase flow generated by immiscible fluids. Saitta was looking for a one-step manufacturing process that could guarantee optical transparency and a tailored surface chemistry without need for further assembly.

Finding the Right Materials to Achieve Necessary Functionality

Optical transparency is necessary for the optical detection of immiscible fluids. The two fluids, marked with diverse reactive index values, have different light transmission properties under the incident laser. The device also needs appropriate surface roughness and hydrophilic behavior to avoid flow instability within the micro channels. Further assembly could lead to fluid leakage at assembly points. Being able to manufacture the device in one piece avoids fluid leakage.

Schematic of the micro-optofluidic device

Polydimethylsiloxane (PDMS) is typically a preferred choice for micro optofluidic devices. However, PDMS does present some important limitations. The micro channel walls undergo some deformation once exposed to non-polar organic solvents. It is also not easy to permanently attach molecules or polymers to PDMS, limiting the possibility to assemble complex structures.

3D Printing the Micro-Optofluidic Devices

Steps for 3D printing the micro-optofluidic device
Micro 3D printed micro-optofluidic device

Saitta turned to 3D printing to manufacture the micro-optofluidic device in one piece. Using the microArch S140, the team was able to print the device with integrated inlets, outlets, and insertions for micro-optical fibers. BMF’s HTL resin was able to achieve the necessary functionality for Saitta’s devices. The resin’s transparency and hydrophilic behavior provided stable fluid flow and the ability to detect diverse reactive index values. The microArch S140 was also able to manufacture the micro-optofluidic device in one piece, eliminating concerns over fluid leakage.

400µm square channels in the micro 3D printing micro-optofluidic device

“Projection Micro Stereolithography has opened new frontiers in the manufacturing of micro-optofluidic devices.”

– Lorena Saitta, PhD, University of Catania

To learn more, read the full research paper here.