Alveoli‐Inspired Porous Hierarchical Iontronic Sensor for Highly Sensitive and Linear Three‐Dimensional Force Detection

ABSTRACT Developing high‐performance three‐dimensional (3D) force sensors that endow robots with both contact and slip perception capabilities is critical for robotic intelligence. While iontronic pressure sensors offer a promise for 3D force sensing with their ultrahigh sensitivity and high noise immunity, they suffer from a trade‐off between sensitivity and linearity. Here, we introduce a novel alveoli‐inspired strategy utilizing a porous hierarchical hemispherical microstructure to achieve both high sensitivity and excellent linearity. Inspired by the hollow and spherical clustering architecture of alveoli, the sensor achieves linear sensitivity of 1558 N − 1 ( R 2 > 0.99) within normal force range of 0–5 N, and 951.8 N − 1 ( R 2 > 0.99) within shear force range of 0–1 N. This linearity is attributed to a graded contact mechanism, which is enabled by the porous hemispherical microstructure compensating for structural stiffening. The sensor demonstrates rapid response (27 ms) and recovery (18 ms) times, and stable performance over 15000 loading‐unloading cycles. We demonstrate the sensor's versatility by integrating it into a robotic gripper for precise manipulations, including stable beaker grasping and simulated surgical procedures. Additionally, a 3D sensor array is developed for multi‐directional contact force mapping. This work establishes a novel manufacturing strategy for high‐performance 3D force sensors with promising applications in intelligent robotics.