A Wireless Sensor-Brain Interface System for Tracking and Guiding Animal Behaviors Through Closed-Loop Neuromodulation in Water Mazes

Abstract

This article presents a wireless sensor-brain inter- face (SBI) system designed for closed-loop neuromodulation in freely behaving animals. The system enables a novel experi- ment in which swimming rats navigate a water maze guided exclusively by neural stimulation. The system consists of two wirelessly linked application-specific integrated circuits (ASICs): a bidirectional neural interface and an animal-tracking image sensor. The neural interface ASIC features a novel stimula- tor design with adaptive termination-based charge-balancing and an energy-efficient neural recording front end that rejects stimulation artifacts. The animal-tracking image sensor extracts the swimming features of rats and maps them into stim- ulation parameters with hardware acceleration. Low-power ultra-wideband transceivers with a custom protocol have been developed to ensure reliable wireless communication between devices with a short latency, which is critical to closed-loop neuromodulation. Wireless power transfer and near-field data communication have been developed to allow a part of the neural interface to be implanted beneath the skin, eliminating the need for through-skin connectors. Both ASICs were fabricated using 180-nm CMOS technology, fully characterized on the bench, and have been successfully used in animal experiments. Through rigorous testing, the system demonstrated consistent success Manuscript received 25 August 2023; revised 5 November 2023 and 26 December 2023; accepted 15 Jan