3D Printing for Neuroscience
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Ramblin’s about 3D printin’
3D printing is an innovative, inexpensive, and highly customizable method of fabrication that has recently become applicable to neuroscience. It is forever changing, and we have helpful tips throughout our projects posted on this site, but it may be useful to dedicate a post to a solid rambling about the current state of 3D printing, and what can be done with its current and most widely used methods.
Let’s go over how to get a 3D model, file types, printing technology, and materials, why not.
Software
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3D Scanners: Good 3D scanners are still kind of expensive and don’t really meet the needs of neuroscience. There are inexpensive systems (such as the Cowtech) which are suitable for some applications, but get thrown off by smaller objects and objects with fur. Typical workflow goes through a variety of steps, ultimately putting out a STL.
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Design: There are many software applications that are appropriate for engineering up some 3D modeling. With these programs, you typically use either basic math equations or (hopefully) a model base system to create drawings, then solids based off of the drawings. They save in file types such as .sldprt (SolidWorks Part), .ipt (Inventor part), .object (general), and .step (general). Solidworks is typically thought of as the gold standard, but is rather expensive. AutoCAD Inventor can be obtained for free with a .edu and is a somewhat cumbersome, but overall solid engineering piece of software. Blender is free and open source, but more for art than engineering. OpenSCAD is pretty popular, free, and can run on Linux. All these programs can export into a .stl file type.
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STL: A good 3D Design software can export into the shareable file type called .stl. These are files made up of hundreds to millions of triangles (triangles happen to be the easiest way to define a solid while minimizing the computation required). They are considered the standard files for sharing. But note that while it is rather easy to go from design file type to .stl, it isn’t super easy to go from .stl back to design file. It can be done (ex: Inventor can use an app called Mesh Enabler to convert .stl to .ipt), but it requires some fancy hand waving and is computationally expensive. This is why a good designer will share both file types.
These files are widely shared, often for free. Check out Thingiverse for a whole bunch of neat designs (some just for lab equipment!); Open-Labware.net is another great resource, specific for lab equipment. Also note that some companies (ex: Thorlabs) share their designs as .stl’s which can be 3D printed (cough cough).
.stl’s can become corrupted (example: Missing triangles result in not a solid part). Programs like Meshmixer can help with this and are free. It is a great program to do minor .stl edits
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GCode: 3D printers cannot directly accept .stl filetype. Having a set of triangles does little to tell a printer how to move around and create the part. Most printers therefore need instructions about heat, movement, speed, etc. That’s where the .gcode filetype often comes in. Free programs like Meshmixer or Cura take .stl’s and a given printer and some instructions from you (ex: Printing resolution), and it writes instructions for the printer on what to do. And because some print technologies require deposition of material in spaces without material below it, these programs can automatically define supports for you. These supports can be removed after the print.
Printing Tech and Materials
FDM
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Fused Deposition Modeling (FDM) is the most inexpensive and widely adapted method for 3D printing. Think of it like a hot glue gun attached to motors that move it in the X-Y plane until an entire layer is deposited, and then another motor moves in in the Z for deposition of the next layer. It’s pretty basic, but can achieve quite a bit for little cost.
- Materials: The standard FDM material to print in is ABS. It is strong, heat tolerant, and easy to print in. But note: It releases toxins during the printing process, and is toxic for animals should they eat it (which they will try). PLA or nGen (ONE Core preferred) are good alternatives. Nylon can be FDM printed, and can be autoclaved, but requires very high temperatures that can break a printer (that was a fun day). FDM can also utilize flexible, clear, and nearly indestructible materials, such as ninjaFlex. But note that these materials typically require unique print heads. There are other cool materials out there, but note that conductive materials are not really that conductive. None of these materials are really ‘biosafe’.
Need 3D prints to be biosafe, but don’t require great tolerances? Try painting on wood glue. Seriously! Titebond 3 is FDA approved for indirect food contact (frequently used for cutting board fabrication). It is super easy to clean up, very restive to chemical penetration, and can aid in water/liquid sealant.
SLA
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Stereolithography (SLA) is another very popular 3D printing technology that can achieve higher resolution, more watertight, and more biosafe prints. Typically, with this technology, a platform is lowered into a vat of resin and a laser hits the platform, heating it, solidifying a very small area of the resin. Mirrors move the laser around. After a layer is solid, the platform raises a bit, and the next layer is solidified.
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SLA can come in a wide variety of materials and colors. Should the part come in direct skin contact, I recommend printing in something that is ‘biosafe.’ Note that MED610 is marketed for dental and implants. It prints beautifully and can come in clear. ONE Core testing has also shown this material to be superior for cell culturing (in that it leaches much less toxic chemicals and will not embed proteins between tests) compared to other 3D printing materials.
Polyjet
- Polyjet is the last printing technology that I will touch on here. I don’t have one of these, so I never looked into how the technology works. These printers can be more expensive, but can print some beautiful designs. Printing generally doesn’t require supports because the process is done in a support gel that is later removed. Prints can come in a whole slew of beautiful colors.
Resources
Check out Thingiverse for a whole bunch of neat designs (some just for lab equipment).
Don’t have an FDM printer? Support the ONE Core and order though us!!!! Or use an inexpensive outside 3D printing shop. Rosenberg Industries is aware of ONE Core projects and requirements, and has a proven track record with ONE Core projects. Don’t have an FDM printer? Support the ONE Core and order though us!!!! Or use an inexpensive outside 3D printing shop. Rosenberg Industries is aware of ONE Core projects and requirements, and has a proven track record with ONE Core projects.
ONE Core acknowledgement
Please acknowledge the ONE Core facility in your publications. An appropriate wording would be:
“The Optogenetics and Neural Engineering (ONE) Core at the University of Colorado School of Medicine provided engineering support for this research. The ONE Core is part of the NeuroTechnology Center, funded in part by the School of Medicine and by the National Institute of Neurological Disorders and Stroke of the National Institutes of Health under award number P30NS048154.”
