KineMouse Wheel and Head Fixation System

During my time as a research intern for the NeuroMechatronics Lab at CMU, I built the KineMouse wheel from Dr. Richard Warren from Columbia University and paired it with a head fixation system inspired by that developed by Dr. Isaac Weaver from Duke University. This wheel and head fixation system was used to study the gait of mice post-stroke.

For the mouse wheel, I followed instructions on how to build Dr. Richard Warren's KineMouse wheel from Columbia University from this paper. Building the wheel involved laser-cutting spokes, supports, and a mirror from acrylic, cementing polycarbonate to the spokes, and positioning the wheel on the axle. The acrylic and polycarbonate wheel is transparent, and the mirror is positioned at a 45 degree angle to allow a camera to capture simultaneous sagittal and ventral views of the mouse during gait.

Building the mouse wheel.

Mouse wheel with spacers.

IMG_6019.mov

Spinning mouse wheel.

While building the KineMouse wheel, I was tasked with building a head fixation system to anchor the mouse at the top of the wheel. For the head fixation system, I drew from this paper by Dr. Isaac Weaver from Duke University that details a 3D printable head fixation system for mice. I modified the setup by adding adjustable optical posts, and lengthening the 3D printed head mounting hardware.

Putting It All Together (But Realizing My Mistake!)

After modifying the length of the head mounting hardware, I realized a critical mistake: I had aligned the mouse wheel perpendicular to the orientation needed to properly fix the head implant with the head mounting hardware. I could not switch the orientation of the mouse wheel to that shown below because it would cause the optical posts to block the camera's view of the mirror.

The above photos show the orientation of the mouse wheel such that the implant is correctly aligned to the head mounting hardware but the mirror view is blocked by the optical posts.

The above photos show the orientation of the mouse wheel such that the mirror view is not blocked by the optical posts but the implant is incorrectly aligned to the head mounting hardware. I decided that the mouse wheel needed to be oriented as above, which meant that my next step was to revise the implant and the mounting hardware.

Revising the Implant and the Head Fixation System

During my revision of the implant and the head fixation system, I was asked to find a way to make the head implant so that it could be manufactured by laser cutting because the 3D printed head implants took multiple days to manufacture due to using an on-campus service. I chose to retain the octagonal shape of the head implant but added "wings" similar to other implants I found online. I also changed the head mounting hardware to take on a "hockey stick" shape, such that the optical posts could stay in a position where they did not block the camera view of the mirror. My revised implants and head fixation system are shown below.

Top view of "hockey stick" head mounting hardware. The implant is secured with small screws to the mounting hardware.

Side view of "hockey stick" head mounting hardware.

First iteration of implant. Position of butterfly wings moved away from mouse eyes, however wings are too long and unevenly balanced on the mouse's head.

Second iteration of implant. Position of the butterfly wings moved and length shortened.

Final iteration. Wing length dramatically reduced and screw hole size decreased.

The above implant and head fixation system served as the final "first prototype" of a mouse wheel and head fixation system for use during the study of mouse gait post-stroke. Upon testing the implant, we experienced difficulty getting the implant to adhere to the mouse skull with the dental cement, especially when the mouse was placed on the wheel and fixed using the head mounting hardware. Additionally, aligning and inserting the screws into the implant holes proved to be a challenge, with two people required, one to hold the mouse and another to align the screws. Further iteration is needed to improve this head fixation system.

This project was a valuable introduction to developing testing set-ups in biomedical research and furthered my interest in design. Check out the motorized obstacle I built that pairs with this mouse wheel and head fixation system.

Page updated

Google Sites

Report abuse