paving the way for more accessibility and faster fabrication of these microscale devices, which multiple scientific disciplines find useful..

Scientists from Singapore University of Technology and Design (SUTD) have taken a new approach to print the microchannels found in microfluidic devices, researchers said.

Concept and demonstrations of microfluidic devices fabricated using a direct ink writing 3D printer. (Source: Singapore University of Technology and Design)

A team from SUTD’s Soft Fluidics Lab led by Assistant Professor Michinao Hashimoto applied the 3D-printing method direct ink writing (DIW) of fast-curing silicone sealant to fabricate microfluidic devices rapidly on various substrates, including glass, plastic, and membranes.

The research means that scientists can turn design of such devices—used in fields ranging from engineering to biology–into actual working prototypes in hours rather than the days it takes with current production methods, researchers said. It also reduces the amount of materials typically used to develop microfluidic devices, creating less waste, they said.

Microfluidics is the manipulation and study of sub-microscopic liters of fluids, and is a boon to scientists because experiments can be performed on a device about the size of a coin, researchers said. This reduces the amount of reagents used, wastes produced, and the overall costs, as well as reduced reaction times and improved control over the reaction conditions, they said.

Days to Hours

The principal method for fabrication of microfluidic devices used today is soft lithography, in which elastomeric materials are casted on a mold fabricated in a cleanroom. This process, while successful, takes several days to go from design to prototype, researchers said.

Key to the method for fabricating these devices designed by the SUTD team is that it determines the design of fluidic channels by a patterned silicone sealant, using the top and bottom transparent substrates to seal the channels, Hashimoto said in a press statement.

“Our approach to apply DIW 3D printing allows direct patterning of microchannels essentially on any flat substrate,” he said, noting the benefit of the process over current methods of fabrication.

The use of transparent substrates allows the researchers to image the channel using a microscope, while also allowing for the fabrication of microfluidic channels that are dynamically tunable in dimensions, Hashimoto said. These dynamically tunable channels can serve as small channels as well as tunable flow resistors in the device, he added.

Researchers used a a MUSASHI Shotmaster 350 printer for their research, Terry Ching, an engineering graduate student at SUTD who worked on the project, told Design News.

“By controlling the distance between the top and bottom substrates, we were able to precisely reduce the channel width up to around 30 microns,” he said in a press statement. “This lateral dimension of the channels would be difficult to obtain if commercially available 3D printers were employed.”

Lab-on-a-Chip Made Easy

A key application for the method is the rapid fabrication of what’s called a lab-on-a-chip, which basically shrinks the entire laboratory down to a tiny footprint, drastically reducing the number of resources used, Ching told Design News.

“We demonstrated the ease of patterning of silicone barriers directly on an off-the-shelf printed circuit board (PCB), immediately integrating electrodes into the microchannels that would function as real-time flow sensors,” he told us.

Researchers also demonstrated other experiments using the printed devices that make it easier for scientists to do their work, including “rapid integration of semi-permeable membranes to microchannels for culturing Keratinocyte cells,” Ching told Design News. “This would mean easy integration of cell cultures,” he said.

The team published a paper on its work in the journal Sensors and Actuators B: Chemical.

Researchers plan to use their method to replace soft lithography in their lab to create microfluidics devices for both lab-on-a-chip as well as organs-on-a-chip applications, Ching told us.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.