Design Considerations for Ground Referencing in Multi - Module Neural Implants

Implantable neural interfaces have evolved in the past decades from stimulation-only devices to closed-loop recording and stimulation systems, allowing both for more targeted therapeutic techniques and more advanced prosthetic implants. Emerging applications require multi-module active implantable devices with intrabody power and data transmission. This distributed approach poses a new set of challenges related to inter-module connectivity, functional reliability and patient safety. This paper addresses the ground referencing challenge in active multi-implant systems, with a particular focus on neural recording devices. Three different grounding schemes (passive, drive, and sense) are presented and evaluated in terms of both recording reliability and patient safety. Considerations on the practical implementation of body potential referencing circuitry are finally discussed, with a detailed analysis of their impact on the recording performance.