3D Printed Skull Cap and Benchtop Fabricated Microwire-based Microelectrode Array for Custom Rat Brain Recordings

Microwire microelectrode arrays (MEAs) have been a popular low-cost tool for chronic electrophysiological recordings. Multi-MEA implantations can reveal electrical dynamics crucial to brain function. However, both the fabrication and implantation procedures for multi-MEAs on a single rodent are time-consuming and highly manual skill-dependent for quality. To enable in-house design, fabrication, and implantation of custom microwire MEAs, we developed (1) a computer-aided designed and 3D printed skull cap for pre-determined implantation locations of each MEA and (2) a benchtop fabrication approach for low-cost custom microwire MEAs. A proof-of-concept design of 32-channel 4-MEA (8-wire each) recording system was prototyped and tested through Sprague Dawley rat recordings. The skull cap design based on CT-scan of single rat conforms well with multiple Sprague Dawley rats of various size, age, and weight with minimal bregma alignment error. The prototyped 32-channel system were able to record spiking activities over 5 months. In comparison with conventional stereotactic surgeries, the skull cap system simplifies the implantation location alignment for each MEA by embedding them into the pre-printed designs, thus dramatically reducing the surgical time and effort and increasing the accuracy and repeatability. Compared to commercially available custom microwire MEAs, this in-house fabrication method enables neuroscience labs to create a custom recording apparatus with lower cost and shorter lead time for design modifications. A new methodology for neuroscience labs to fabricate and insert custom microwire MEAs has been developed and it could be easily generalized to enable low-cost highly-custom multi-region recording/stimulation studies. Highlights ### Competing Interest Statement The authors have declared no competing interest.