We have developed a passive Electrical Rotary Joint usable for electrophysiological experiments that can be combined with fiber-optic rotary joints (1x1 or 1x2) to bring light to and/or from the sample. Its 7.2 mm through hole in the center is sufficient for passing fiberoptic patch cords with M3 connectors or ferrule/sleeve type connectors. It is also convenient for fluid tubing allowing drugs administration during electrophysiological experiments with freely-moving animals. Our Electrical Rotary Joint has a torque as low as 0.9 mN·m (for 6 electrical contacts) or 1.8 mN·m (for 12 electrical contacts), acceptable for use with rats or larger animals. They are optimized to offer the best electric signal with the lowest torque, given that stable electrical transmission with small resistivity variations during rotation requires the increase of contact areas between each electrical contact. For small animals like mice, we recommend our Assisted Electrical Rotary Joints to remove the torque originating from the friction of the electrical contacts.

Notes:

• The number of electrical contacts does not necessarily equal the number of recording channels.
• Holders allowing the mounting of an Electrical Rotary Joint with a Fiber-optic Rotary Joint (1x1 or 1x2) are included (Holder_ ERJ, Holder_FRJ_small and Holder_FRJ_large).
• If the Electrical Rotary Joints is used only for electrophysiology, without any additional fiberoptic rotary joints, a compatible holder is already included (Holder_FRJ_large).
• An optional horizontal cable holder keeping cables off-center can be added to increase the effective torque applied on the rotor (HCH). Electrical Rotary Joints come with the pre-installed adapter allowing the fixing on the optional horizontal cable holder.
• An optional gimbal holder can be used to pivot and rotate the rotary joint around an axis (GH_FRJ).
• An optional adapter kit can be provided to allow a Harwin-connectorized rotary joint to be used with an Omnetics-connectorized systems (ADAPTER_HO12).