Robotic optical coherence elastography system for <i>in vivo</i> 3-D structural imaging and elasticity mapping in skin

Evaluating biomechanical properties is crucial to manage skincare and help guide skin cosmetic and reconstruction procedures. Recent development in wave-based optical coherence elastography (OCE) has shown promise for noncontact stiffness measurements in skin and ocular tissues. Integrating multiple OCT modalities—structural and polarization-sensitive OCT, angiography, and optical OCE enables detailed assessment of tissue structure and function at micron-scale resolution. Previous approaches to anisotropic elasticity imaging involved noncontact shear-wave sources and multi-angle acquisitions, but manual rotation limited resolution and increased acquisition time. This study presents a fully automated, fiber-optic robotic system for noncontact monitoring of skin graft surgeries, integrating four OCT modalities. A 1310 nm swept-source OCT system was mounted on a robotic cart with a custom cylindrical acoustic micro-tapping transducer, launching Rayleigh waves in skin through air. The system achieves a 16 μm lateral and 12 μm axial resolution of structural images, with a 9 mm × 9 mm field of view. The robotic arm provides autofocus, automates imaging head rotation, and acquires waveforms along 19 in-plane angular positions to reconstruct anisotropic mechanical moduli using a nearly incompressible transversely isotropic (NITI) model. In vivo measurements on healthy volunteers demonstrated the system's ability to capture structural, functional, and mechanical properties of skin, providing promising results for clinical translation.