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Millifluidics and Microfluidics Geometries Using Stereolithography (SLA) 3D Printing

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Desktop Stereolithography (SLA) printing continues to create new opportunities for affordable in-house printing. Critical microfluidic chip designs, used in engineering applications, advanced medical analysis, and educational institutions, can be designed and printed in-house with current generation, high resolution 3D printers. Microfluidic devices contain channels less than 100 micrometers in size, but larger channels can often achieve the same level of fluid mixing depending on the project requirements.  

Formlabs created a free report that looked at millifluidics chips, with channel sizes larger than 100 micrometers, created using Formlabs Clear Resin. We ran dyed water through the channels to observe laminar flow as channel sized decreased, and recorded the results. Below, read some of the benefits we discovered while printing these millifluidics chips.

Reason to Print Fluidic Chips In-House

Additive manufacturing provides a number of benefits over traditional chip production methods. Two benefits include the significant cost savings due to in-house printing, and the ability to quickly test complex three-dimensional designs. 

Cost Savings

The first and most significant is the cost savings associated with in-house 3D printing. Ordering a custom-made millifluidic chip normally incurs an exorbitantly high cost and can take up to two
months before having a prototype in-hand. Instead, SLA machines can print any geometry
needed right in your lab and have it ready in hours, not months.

A single large chip, which prints at the maximum size possible on the Form 3, will use approximately 57mL of Clear Resin at a cost of $8.55; thin chips can use substantially less resin than 57mL, further reducing the cost per-chip. This compares to traditional chip manufacturing which cost significantly more, while taking weeks to arrive. In our estimate, lithography techniques can cost  $73.75 per chip on average.

A single build platform of chips can print in under 24 hours.

3D and Custom Designs

The second benefit is quick print times for new chips. This allows teams to test chips quickly, which means more tweaks and new parts based on real time feedback from labs. Complex designs are only limited by what a user can create in CAD, opening up quick testing of microfluidic and millifluidic chips in labs for the first time. This can especially be helpful for students looking to understand how different liquid and channels mix fluids. 

Sharp 3D features disrupt laminar flow in narrow channels and allow the designer to control when and how fluids mix.  The Formlabs engineering team wanted to test these 3D features, so they designed, printed, and tested a unique 3D millifluidic geometry containing a twisting channel. The mixers were tested using standard food dye dissolved in tap water. One syringe was filled with yellow, the other blue. Each color was injected into a mixing port printed directly to the chip. Then the mix was projected onto a white surface where the uniformity of the mix could be observed.

Formlabs offers several options for optically clear resins, offering another benefit to 3D printed chips, as different materials may offer better chip design and mixing properties. While Clear Resin (in the standard resin family) is great for prototyping, Dental SG and High Temp Resins can also provide the required properties for common millifluidics applications.

Dental SG is more rigid than Clear Resin. It excels at resolving negative features and is an autoclavable biocompatible material. Dental SG can also print with a 50 micron layer height for super precise channel geometry. This could help push chip and channel designs even smaller, enabling truly microfluidic 3D printed chips.

Download Our Free Report

In-house microfluidic and millifluidic chip production comes with its own host of problems and challenges. To fully understand the benefits and challenges involved, check out our free report: “Desktop Millifluidics With SLA 3D Printing”.

  • Download our free report on this topic to understand:
  • How much it costs to print chips on a Formlabs 3D printer.
  • Examples of sample test prints.
  • Best practices for print orientation for millifluidic chips.

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