Here is our modular infrared position tracker design for locomotor activity tracking. By monitoring individual infrared beam breaks we can determine instantaneous location of a rat or any opaque object within a plane. We have confirmed this design can be used to accurately track animals in our chambers, but it should be usable in any application that requires 2-axis position tracking. Stacked trackers could theoretically add a third tracked dimension. We have available two spacing sizes for rats and mice, respectively (mice can “disappear” on the rat tracker since they are small enough to fit between beams). Renders were created using Blender. Corresponding photographs show the completed trackers ready to install. To download .stl files of individual pieces, right click one of the file links under the pictures and select “save link as…”


Exploded position tracker render to show: 3mm and 5mm LED holder trios, corner pieces, and tracker stands. Transparent to show LED housings.

Wired position tracker ready to install (No PCBs)

PCB position tracker ready to install

Rat grid (larger spacing):

4x Corner Pieces

2x 5mm LED holder trios (3 position)

2x 5mm LED holder quartets (4 position)

2x 3mm LED holder trios (3 position)

2x 3mm LED holder quartets (4 position)

4x Tracker stand (5cm base)

for PCB designs, see: Tracker PCBs

Mouse grid (smaller spacing):

Mouse designs print in fewer, larger pieces, but are more susceptible to curling during printing

4x MousePosTrack_Corner Pieces

1x MousePosTrack_5mm LED holder (11 position)

1x MousePosTrack_5mm LED holder Duo (2 position)

1x MousePosTrack_3mm LED holder (11 position)

1x MousePosTrack_3mm LED holder Duo (2 position)

4x Tracker stand (5cm base)

Note: Half of the LED holders should be 3mm to house IR emitter LEDs; the other half should be 5mm to house IR photodetectors and mounted opposite the emitters to have a full grid of IR beams. 4x Holder Stands and Triangle Corner pieces should be sufficient for any size design.