HeadCaps
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A rigid and detailed 3D Printed brain access port with stabilization
Neuroscience has been greatly advanced with high resolution electrical recordings and imaging in living animals. Such recordings and imaging can be challenging due to movement artifacts. These artifacts are minimized when the recording medium is held static relative to the object of interest (BRAINS). HeadCaps (headplates) are designed to do this, while minimizing potentially negative impact to all other study considerations (e.g. weight). There are many designs of headcaps, some of which are detailed over at Labrigger. These designs are fabricated using expensive machining and heavier materials, under the assumption that high strength metals are required to minimize even the smallest deflection due to any force.
But, a correctly designed 3D print will experience no more deflection than a similar high strength metal. For a given weight, one can utilize more material in a plastic part to achieve the same level of stiffness as the metal. That is to say, these might be slightly thicker, but they weigh the same. And 3D printing allows for unique designs; designs that are unrealistic or impractical by conventional machining methods. Achieve your research with these free designs, suitable even for Neuropixel or 2-photon imaging.
The flexibility of this design allows for many, many tweaks. Many different iterations offer unique benefits. For the sake of brevity, here we offer only a couple of iterations to show the possibilities, but know that we can customize the design to meet an even wider variety of needs. Have an idea for an iteration? Send us an email (maybe we’ve already designed it!).
Files
Here are the files (click on an stl to view the part in your browser). These should be 3D Printed in a high resolution, high strength material, such as the Formlabs Rigid 4000. Don’t have an SLA 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.
| Name | File Type | Design/Description |
|---|---|---|
| HeadCapBase.ipt | ipt | Base |
| HeadCapBase.stl | stl | Base |
| HeadCapTopHat.ipt | ipt | Cap |
| HeadCapTopHat.stl | stl | Cap |
| HeadCapBaseRod.ipt | ipt | With rod holders |
| HeadcapBaseRod.stl | stl | With rod holders |
| HeadCapBaseRodAngled.ipt | ipt | Rod Holders with Angle |
| HeadCapBaseRodAngled.stl | stl | Rod Holders with Angle |
| HeadCapBaseNP.ipt | ipt | Neuropixel Design |
| HeadCapBaseNP.stl | stl | Neuropixel Design |
| StereotaxicNeuroprobeamajigerHeadCap.ipt | ipt | Stereotaxic NP clamp |
| StereotaxicNeuroprobeamajigerHeadCap.stl | stl | Stereotaxic NP clamp |
Designs
The first part is the base design. It is extremely light, has no way to allow for head fixation, but is intended to be an access port utilized with the TopHat. With this, you can access the brain region of your choice, then apply the TopHat to keep everything all nice and clean, and access the area later on. The ridges allow for securing the part down with something like dental cement.
The cap (referenced as the TopHat above) fits into the base design (and other designs below). With an intuitive drop-in and quarter turn clockwise, you can secure the access point.
I couldn’t decide what tool to use to secure it in place, so I designed it for all tools: Hex, flathead screwdriver, pliers, fingers, whatever you got.
Next is the HeadCapBaseRod which conforms to the usual 2 mm diameter rods that are frequently utilized for these experiments.
A typical set up (these parts can be printed in very inexpensive FDM, I have the files somewhere).
The ‘bottle cap’ ridges fasten the part to the skull well. There are four arrows that indicate relative orientation (more on that later).
There are access holes for having grounds and other wires secured.
Here is the size compared against a typical mouse skull. You can use the four arrows relative to bregma/lambda for orientation purposes. In addition, there are markings on the top that allow for incredible precision, with each radial line indicating 5 degrees.
Folks around these parts like to look at rostral brain areas. We therefore offer the following RodAngled part to show that adding some slight angle to the base relative to the rods can be beneficial. Update the design file for getting the angles you need.
Other folks like to use their old Neuropixel holder design for their experiments. We therefore show the base design with the NP modification. Note the additional holes for grounding wires.
And finally, here is a part that can be used for holding the NP headbars/headcaps. It can be printed in inexpensive FDM printing and holds against a stereotaxic rod with a basic 6-32 nut and screw. Then, because we are total meanies, we switch from Imperial to Metric: you use an M3 nut and screw to clamp onto the NP itself. Sorry.
ONE Core Acknowledgment
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.”
