Compact Low-Power Interfacing and Data Reduction for Floating Active Intracortical Neural Probes With Modular Architecture

Abstract

Host connectivity for invasive, high-density neural probes that integrate all the circuits needed for in-situ digitization of brain activity in the shank requires a thin and conformal cable. To minimize tissue damage during insertion or from micro-movements during chronic use, the wiring must be constrained in size with a low number of interconnects. Reducing the number of traces results in thinner and more flexible cables and allows the data rate to be increased by using wider traces. Fewer contacts are also less susceptible to reliability issues in long-term applications. This paper presents a modular digital neural probe that embeds a two-wire bidirectional interface for host connectivity minimizing the data overhead for configuration and readout. The presented handshaking allows synchronization of multiple shanks and is designed to adapt to varying line delays caused by different cable lengths or changing environmental conditions. Data reduction based on delta encoding further increases the number of electrodes that can be read out simultaneously. The system is validated in a 192-channel neural probe fabricated in a 180 nm CMOS technology with a supply voltage of 1.2 V.