Direct Resolution of Three-Dimensional Gaze for Spatial Interaction via a Smart Contact Lens

As eye-machine interaction (EMI) systems evolve towards more immersive and spatially distributed environments, a key challenge lies in reliably capturing and utilizing fixation depth for precise interaction in real-world settings. However, existing eye-tracking technologies estimate fixation depth indirectly through geometric reconstruction or binocular triangulation, limiting robustness and wearable deployment in spatial environments. Here we present Embobi, a non-invasive, wireless, and chipless smart contact lens that enables direct resolution of three-dimensional gaze at the ocular interface. By transducing accommodation-induced corneal deformation into resonance-frequency shifts of an integrated inductive coil array, the system jointly captures gaze direction and fixation depth without reliance on scene cameras or dual-eye triangulation. Dedicated gaze decoding and edge-level inference algorithms structurally decouple depth and direction at the sensing node, enabling stable reconstruction of three-dimensional points of regard. Validation across eye phantoms, ex vivo porcine eyes, and in vivo rabbit models demonstrates gaze-direction accuracy comparable to commercial eye trackers alongside repeatable depth sensing. Representative interaction scenarios illustrate that physiologically resolved fixation states can function as continuous control variables, enabling spatially anchored eye–machine interaction. This work establishes a pathway toward physiology-grounded on-eye interfaces in which perceptual states can serve more directly as interaction signals.