Ultraflexible photoelectrical impedance tomography-based imager for 3-axis robotic tactile sensing

Vision-based robotic triaxial tactile sensing provides superior spatial resolution and rich multimodal data. However, employing rigid CMOS imagers suffers from limitations in mechanical flexibility and large-area scalability. Here we present a large-area ultraflexible photoelectrical impedance tomography (PIT)-based imager that achieves high-fidelity triaxial tactile sensing. The 5-μm-thick PIT imager incorporates a quantum dots/metal-oxide heterojunction layer with 16 peripheral electrodes, significantly reducing interconnects complexity (pixel-to-interconnect ratio >80). The device exhibits a photo-to-dark-current ratio exceeding 10⁴ under ultraviolet illumination, resolves spatiotemporal features as fine as 1.5 mm, and can simultaneously image up to five occluded regions. By integrating a thin light-scattering porous rubber and flexible LEDs, triaxial force decoding is achieved through Gaussian photocurrent analysis. The system achieves over a dynamic range of 80 kPa with a normal force sensitivity of 0.04 kPa⁻¹, a shear displacement resolution of 0.17 μm kPa⁻¹, and a topological recognition accuracy of 96.5%. We anticipate that this technology will enable advanced applications in industrial and humanoid robotics, medical and rehabilitation robotics, and wearable health monitoring and human-machine interaction systems.