Mar 28, 2017 | By Benedict

Researchers at Justus Liebig University in Giessen, Germany, have used a modified Prusa i3 3D printer to create thin layers of silica gel which can be used for thin layer chromatography, a lab technique for separating mixtures into their individual ingredients.

The Prusa i3 is a versatile 3D printer, but we doubt any makers have used the RepRap machine to fabricate a mixture-separating silica gel. Until now, that is…

Thin layer chromatography (TLC) is a form of chromatography, a process used in scientific research, quality control, and other fields in order to separate mixtures into their constituent parts. The unique feature of TLC, which dates back to 1938, is that it uses a thin layer of an adsorbent such as silica gel in order to draw out parts of a mixture at different levels, leaving the constituent parts clearly separate. (Other methods use special chromatography paper or other tools for separation.)

Researchers at Germany’s Justus Liebig University recently found that, by 3D printing the layer of silica gel, a kind of “patterned plate,” they could carry out the process of TLC in a highly affordable and effective manner.

Lab equipment for carrying out TLC can be expensive, but these Justus Liebig researchers, Dimitri Fichou and Gertrud E. Morlock, discovered that a modified Prusa i3 3D printer could be used to create the silica gel layers required for this particular form of planar chromatography.

The 3D printer's slurry doser modification in digital (A) and 3D printed (B) form

Makers will recognize the Prusa i3 as one of the more popular open source RepRap machines out there, though few will ever have used the 3D printer to print silica gels. In actual fact, Fichou and Morlock couldn’t do so either—until they made some fairly significant changes to their i3.

These 3D printer hacks involved replacing the i3’s filament-dispensing extruder with a syringe-like tool called a “slurry doser,” which was itself 3D printed, before writing specific G-code that would instruct the 3D printer to deposit the silica gel as needed. The researchers only needed to print a single layer of the silica gel, making it more 2D printing than 3D printing, but the i3’s bed leveling feature was used to full effect in order to guarantee a consistent level of the substance, while its heated print bed helped the substance to dry in as little as five minutes.

“The layer printing process was fast,” Fichou and Morlock explain. “For printing a 0.2 mm layer on a 10 cm × 10 cm format, it took less than 5 minutes. It was affordable, i.e., the running costs for producing such a plate were less than €0.25 and the investment costs for the modified hardware were €630.”

The hacked Prusa i3 3D printer used for planar chromatography

Interestingly, the researchers also found that an entire “plate,” at just 25 cents, was actually more than they needed. They also tried 3D printing 40 channels in parallel on a 10 cm × 10 cm square in order to separate 40 different samples, and found that these channels were just as effective at separating as the plate. This “channeled” print cost only €0.04, and took just two minutes to print.

While this is certainly a niche use for a Prusa i3 or any 3D printer, those interested in the planar chromatography project can check out the research paper or Fichou’s Github repository for the slurry doser modification. The researchers want to keep the entire project open source, so those in the chromatography field can work together to make the new process cheap and accessible.



Posted in 3D Printer



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