Traditional injection and extraction devices often appear painful and cumbersome for patients. In recent years, polymer microneedles (MNs) have become a novel tool in the field of clinical medicine and health. However, the cost of building MNs into any shapes still remains a challenge. In this paper, we proposed hydrogel microneedles fabricated by high-precision digital light processing (H-P DLP) 3D printing system. Benefits from the sharp protuberance and micro-porous of the hydrogel microneedle, the microneedle performed multifunctional tasks such as drug delivery and detection with minimally invasion. Critical parameters for the fabrication process were analyzed, and the mechanical properties of MNs were measured to find a balance between precision and stiffness. Results shows that the stiffness and precision were significantly influenced by exposure time of each layer, and optimized printing parameters provided a balance between precision and stiffness. Bio-compatible MNs based on our H-P DLP system was able to execute drug injection and drug detection in our experiments. This work provided a low-cost and fast method to build MNs with 3D building, qualified the mechanical performance, drug injection, drug detection ability of MNs, and may be helpful for the potential clinical application.

A procedure for 3D printing of silicone elastomers with a direct ink writing (DIW) process has demonstrated great potential in areas as diverse as flexible electronics, medical devices, and soft robotics. In this report, we propose a comprehensive guide for printing highly stretchable silicones in response to material, equipment and process dilemmas. Specifically, we first tested the material properties of Dow Corning 737, then modeled and simulated two commonly used needles to select a suitable needle, followed by parameter optimization experiments using the built DIW printer to find out the appropriate printing speed and layer height with a defined air pressure and needle diameter. Finally, the optimal combination of parameters was obtained. For further demonstration, artificial muscles and structurally complex soft grippers were also printed directly to verify the feasibility of high-precision 3D printing of soft actuators with soft materials. We believe that this work could provide a guide for further work using the DIW process to print soft matter in a wide range of application scenarios.

Currently, soft robots face challenges such as low motion efficiency, susceptibility to damage in traditional silicone materials, and difficulty in achieving reproducible manufacturing. To address these issues, we integrate flexible film materials with modular design principles and apply them to soft robotics. Based on the concept of modularity, this study simplifies and decomposes the robot's motion into three fundamental modules: a thin-film elongation actuator module, a thin-film deflection actuator module, and a connection module. Inspired by the Miura-fold origami technique and traditional lantern contraction, the elongation actuator is designed to produce axial extension of varying lengths under different air pressures. The deflection actuator is modeled after the head expansion mechanism of the pelican eel, enabling deflection movement. The connection module integrates the elongation and deflection modules into a unified structure. The research results show that the elongation actuator achieves an extension length of 118mm under 50kPa, and can pull a 500g load during horizontal contraction. The two-layer deflection actuator achieves a deflection angle of 56° at 40kPa, while the three-layer version reaches 98°. For further demonstration, we subsequently conducted peristaltic soft robot experiments and obstacle avoidance experiments. This study holds significant potential for the development of next-generation multi-functional soft robots.

Currently, soft robots face challenges such as low motion efficiency, susceptibility to damage in traditional silicone materials, and difficulty in achieving reproducible manufacturing. To address these issues, we integrate flexible film materials with modular design principles and apply them to soft robotics. Based on the concept of modularity, this study simplifies and decomposes the robot’s motion into three fundamental modules: a thin-film elongation actuator module, a thin-film deflection actuator module, and a connection module. Inspired by the Miura-fold origami technique and traditional lantern contraction, the elongation actuator is designed to produce axial extension of varying lengths under different air pressures. The deflection actuator is modeled after the head expansion mechanism of the pelican eel, enabling deflection movement. The connection module integrates the elongation and deflection modules into a unified structure. The research results show that the elongation actuator achieves an extension length of 118 mm under 50 kPa and can pull a 500 g load during horizontal contraction. The two-layer deflection actuator achieves a deflection angle of 56° at 40 kPa, while the three-layer version reaches 98°. For further demonstration, we subsequently conducted peristaltic soft robot experiments and obstacle avoidance experiments. This study holds significant potential for the development of next-generation multifunctional soft robots.