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. Conventional CMOS imagers are limited in mechanical flexibility and large-area scalability. Here, the authors develop a large-area, flexible photoelectrical impedance tomography-based imager, which can be further integrated for high-fidelity robotic three-axis tactile sensing.