A High-Precision and Large-Range Iontronic Flexible 3D Force Sensor for Robotic Interactions

Flexible tactile sensing plays a critical enabling role in the development of next-generation humanoid robots. Accurate measurement of three-dimensional (3D) force distribution is essential for robotic dexterous hands to perform delicate and complex tasks. However, the development of flexible tactile sensors capable of simultaneously achieving high sensitivity, wide detection range, and 3D force detection remains a significant challenge. In this work, we present a high-precision and large-range flexible 3D force sensor based on iontronic sensing mechanism, with a normal force detection range of$0-15 \mathrm{N}$and a tangential force range from −8 N to 8 N. A continuous dynamic calibration method was implemented by synchronously collecting data from a commercial force/torque sensor and the response of the flexible sensor across the entire detection range. This approach enabled the construction of a comprehensive 3D force dataset containing over$\mathbf{2 4 0, 0 0 0}$samples. Combined with a Random Forest regression model, the system achieved full-scale errors of 0.38% FS for$\boldsymbol{F}_{\boldsymbol{x}}, 0.25 \%$FS for$F_{y}$, and 0.40% FS for$F_{z}$. Furthermore, a real-time demonstration application verified the sensor's accuracy and responsiveness, highlighting its strong potential for integration into robotic systems such as dexterous hands and intelligent prosthetics.