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Liquid metal (LM)-based flexible sensors, which utilize advanced liquid conductive materials to serve as sensitive elements, are emerging as a promising solution to measure large deformations. Nowadays, one of the biggest challenges for precise control of soft robots is the detection of their real-time positions. Existing fabrication methods are unable to fabricate flexible sensors that match the shape of soft robots. In this report, we first described a novel 3D printed multifunction inductance flexible and stretchable sensor with LMs, which is capable of measuring both axial tension and curvature. This sensor is fabricated with a developed coaxial LM 3D printer by coprinting of silicone rubber and LMs. Because of the solenoid shape, this sensor can be easily installed on snakelike soft robots and can accurately distinguish different degrees of tensile and bending deformations. We determined the structural parameters of the sensor and proved its excellent stability and reliability. As a demonstration, we used this sensor to measure the curvature of a finger and feedback the position of an endoscope, a typical snakelike structure. Because of its bending deformation form consistent with the actual working status of the soft robot and unique shape, this sensor has better practical application prospects in the pose detection.

The use of microscale fibers could facilitate nutrient diffusion in fiber‐based tissue engineering and improve cell survival. However, in order to build a functional mini tissue such as muscle fibers, nerve conduits, and blood vessels, hydrogel microfibers should not only mimic the structural features of native tissues but also offer a cell‐favorable environment and sufficient strength for tissue functionalization. Therefore, an important goal is to fabricate morphology‐controllable microfibers with appropriate hydrogel materials to mimic the structural and functional complexity of native tissues. Here, gelatin methacrylate (GelMA) is used as the fiber material due to its excellent biological performance, and a novel coaxial bioprinting method is developed to fabricate morphology‐controllable GelMA microfibers encapsulated in calcium alginate. By adjusting the flow rates, GelMA microfibers with straight, wavy, and helical morphologies could be obtained. By varying the coaxial nozzle design, more complex GelMA microfibers such as Janus, multilayered, and double helix structures could be fabricated. Using these microfibers, mini tissues containing human umbilical cord vein endothelial cells are built, in which cells gradually migrate and connect to form lumen resembling blood vessels. The merits of cytocompatibility, structural diversity, and mechanical tunability of the versatile microfibers may open more avenues for further biomedical research.

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Here, we constructs a whole vascular system, from arteries and capillaries to veins with a high resolution 3D printing. A bulk breast tumor tissue with a functional vascular network was built. The interaction between tumors and vessels is investigated.