3D Printing: Millifluidics vs Microfluidics

< 5 minute read

Recent advancements in 3D printing technologies have brought to the forefront the potential of 3D printers and its applications in the research industry. 

In particular, strong movements have been made in print resolution, whereby the ability to produce sharp fine detail at progressively smaller scales has since become significantly more feasible – opening new doors for scientific studies like millifluidics, and even more so, microfluidics.

The Study of Fluidics: Defining Millifluidics and Microfluidics

Both studies refer to the science of manipulating small amounts of fluids, but at different scales. Millifluidics observes the behaviour of flows through channels with diameters over 1000µm (or 1 mm), and microfluidics with channels anywhere between 1000µm to 0.1µm. Anything below this falls under the realm of nanofluidics, however this goes beyond the scope of this article.

Interest in fluidic systems stems from its abundance of practical applications. However traditional test methods are expensive, produce unnecessary waste, and are relatively more difficult to measure as flow patterns are more turbulent where large volumes of liquid are involved.

This is where milli- and microfluidics come into play. Flows in channels with dimensions from the millimeter and below are laminar and easy to manipulate. Moreover, working with small channel sizes also promotes shorter reaction times and more homogeneous conditions, keeping testing parameters consistent and extreme outliers less likely.

Key Differences

If millifluidic devices offer similar benefits as their microfluidic counterparts, why bother with microfluidic devices at all?

Millifluidic devices require larger amounts of fabrication material, fluid samples and reagents  than microfluidics, all of which can easily add up in cost especially when dealing with hard to come by materials. 3D printing photopolymers specifically for microfluidic applications can cost anywhere between $250-$500 US alone for 500 grams of material. In a similar vein, when handling toxic substances microfluidics is safer as you are now exposed to smaller quantities that are easier to control.

Another factor is freedom of design. A single chip with microfluidic features can house several fluidic systems and design elements. On the other hand, millifluidic chips will house one or two systems before the chip becomes too large – again circling back to the issue of higher material costs.

3D Printing Microfluidic Devices

During the testing phase of our ProFluidics 285D 3D printer we were able to consistently print 50µm open channels and 100µm encapsulated channels. Using our in-house 3D printing materials we were able to fabricate microfluidic devices weighing approximately 5 grams, with each device costing approximately $2.05 – $2.55 US to make.

As a general rule of thumb, when looking to invest in a 3D printer, it is more advantageous to procure a 3D printer capable of producing microfluidic features. A 3D printer optimised for microfluidics is flexible and will print millifluidic designs. On the other hand, 3D printers better suited for millifluidics may not have the means to print microfluidic devices.

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