A Noninvasive Path to Animal Welfare: Contactless, In-Vivo Monitoring of Vital Signs and Activity in Rodents Using a mm-Wave FMCW Radar

Monitoring physiological and behavioral parameters of laboratory rodents is fundamental for biomedical research; however, conventional techniques often rely on invasive sensors or frequent handling, which can induce stress and compromise data fidelity. To address these limitations, this paper presents a contactless and non-invasive in-vivo monitoring system based on a low-power 60GHz frequency-modulated continuous wave (FMCW) radar. The proposed system enables the detection of rodent activity and vital signs directly within home-cage environments, eliminating the need for implants, electrodes, or human intervention. The hardware platform leverages a compact Infineon BGT60 series radar sensor, optimized for low power consumption and continuous operation. We investigate sensor placement strategies and design a complete signal processing pipeline, including range bin selection, phase extraction, and frequency-domain estimation tailored to rodent vital signs. The system achieves 3 cm and 0.1 m/s sensitivity for motion and activity detection, while allowing discrimination of micro-movements associated with pulmonary activity with a 2 μm distance resolution. Experimental validation with two rodents in realistic in-vivo cages demonstrates that the radar can track animal position and extract respiration rates with ±2bpm accuracy. By minimizing stress and disturbance, this work improves both animal welfare and the reliability of physiological measurements, offering a refined alternative to traditional monitoring methods. This work represents the first demonstration of continuous radar-based vital sign monitoring in freely moving rodents within group-housed cages. The proposed approach lays the foundation for scalable, automated, and ethical monitoring solutions in preclinical and translational research.