A Modular Platform for Multimodal Biosignal Acquisition in Freely Moving Animals

Abstract

Multimodal biosignal monitoring is essential for understanding complex neural and physiological processes in freely moving animals. However, most existing systems are bulky, rigidly designed for specific modalities, and lack the flexibility required for diverse experimental paradigms. The acquisition of neural and biological signals in small, freely moving animals greatly benefits from miniaturized, modular platforms capable of supporting diverse sensing, data, and power requirements. To meet these needs, we have developed a compact, reconfigurable electrophysiology (ephys) platform that is capable of simultaneously recording neural and peripheral biosignals while also allowing for flexible integration of sensing modalities, data interfaces, and power sources.

At the core of our design is a 9 × 9 mm² custom “motherboard” based on an ARM Cortex-M4F microcontroller (120 MHz, 1 MB Flash, 256 KB SRAM). This motherboard interfaces with stackable peripheral modules that deliver electrophysiology, electrocardiography (ECG), electromyography (EMG), and environmental sensing capabilities. A high-density electrode interface board interfacing with an onboard Intan RHD2132 ephys chip provides up to 32 channels of electrophysiology recording in a small footprint.

High-throughput data transmission is supported in three ways: (1) wired low-voltage differential signaling (LVDS) to external receivers, (2) wireless near-infrared optical communication at rates up to 12 Mbit/s, and (3) on-board microSD storage handling up to 25 MB/s. Power can be delivered via a tethered connection, onboard lithium-polymer (LiPo) battery, or wide-range wireless power transfer systems, enabling untethered operation when needed.

Initial prototype evaluations confirm stable neural data acquisition over extended recordings and robust performance of the wired communication link. These results demonstrate that our modular ephys platform can accommodate complex multimodal experiments while minimizing the size and weight imposed on freely moving animals. This work presents a scalable, miniaturized electrophysiology platform that prioritizes modularity across sensors, data channels, and power domains—advancing dense, multimodal biosignal monitoring in freely moving animals with minimal physical and physiological impact.