Scalable high-density tactile arenas for measuring ground-contact forces in freely moving animals
Understanding how animals physically interact with their environment is fundamental to studying movement, sensorimotor control, and neurological function. Yet most behavioral measurement systems primarily capture movement and posture, while direct measurements of contact forces often require specialized instrumentation or involve trade-offs among spatial coverage, resolution, and acquisition speed. Here, we introduce a scalable tactile sensing platform that transforms the surface beneath freely moving animals into a high-resolution contact-imaging instrument. By combining modular sensor arrays with adaptive compressive tactile sampling, the platform provides 16,384 tactile sensing elements at 2-mm pitch across a 512 x 128-mm runway, with nominal 1 kHz acquisition. Rather than exhaustively scanning the entire array, the system concentrates measurements around active contacts, enabling high-speed sensing across an extended behavioral surface. Synchronized overhead video and a camera-assisted analysis pipeline enable paw-resolved measurements of contact loading, stance dynamics, footprint morphology, interlimb weight redistribution, and center-of-pressure trajectories. In a longitudinal rat model of sciatic nerve injury, the platform detected reduced loading of the injured hindlimb and increased loading of the contralateral limb, including changes that conventional gait timing measures underestimated. The modular architecture, together with openly available hardware designs, software and data, provides an accessible framework for studying the mechanical interactions underlying freely moving behavior, with potential applications across neuroscience, injury, and motor recovery research.