Direct-Ink-Writing Multifunctional Flexible Robotic Electronic Skin.

Electronic skin for robotics often suffers from limited scalability, high fabrication costs, and inflexible designs, restricting its ability to support multimodal sensing and customization. To address these challenges, we propose a robotic e-skin fabricated using direct-ink-writing technology that enables rapid customization and scalable production of multimodal sensors. The e-skin can detect pressure, temperature, and shear forces through a facile sensor design modification without additional complex fabrication steps. The pyramid-structured tactile sensor demonstrates high sensitivity of 670 kPa-1 in the 0-100 kPa range, maintain long-term stability over 3500 cycles, and exhibits minimal signal drift of less than 3% after 9 days of continuous testing. A 4 × 9 flexible sensor array is developed for real-time pressure mapping on both flat and curved surfaces. Integration with a robotic gripper combined with a K-nearest neighbor classifier achieves a 97.7% accuracy in object recognition. Furthermore, by replacing the sensing layer with a temperature-responsive polymer or incorporating a protrusion-patterned shear layer, the e-skin can function as a dual-mode temperature-pressure sensor or a shear-force sensor. This highly versatile and scalable e-skin platform opens new possibilities for applications in robotics, prosthetics, and human-machine interfaces.