A fully immersible deep-brain neural probe with modular architecture and a delta-sigma ADC integrated under each electrode for parallel readout of 144 recording sites

Abstract

The evolution of tissue-penetrating probes for high-density deep-brain recording of in vivo neural activity is limited by the level of electronic integration on the probe shaft. As the number of electrodes increases, conventional devices need either a large number of interconnects at the base of the probe or allow only a reduced number of electrodes to be read out simultaneously [1,2]. Active probes are used to improve the signal quality and reduce parasitic effects in situ, but still need to route these signals from the electrodes to a base where the readout electronics is located on a large area [3,4]. In this work, we present a modular and scalable architecture of a needle probe, which, instead of routing or prebuffering noise-sensitive analog signals along the shaft, integrates analog-to-digital conversion under each electrode in an area of 70×70μm2. The design eliminates the need for any additional readout circuitry at the top of the probe and connects with a digital 4-wire interface. The presented reconfigurable 11.5mm probe features a constant width of 70μm and thickness of 50μm from top to bottom for minimal tissue damage with 144 integrated recording sites and can be fully immersed in tissue for deep-brain recording applications.