Support-Free Fabrication of Elastic Silicone Microstructures via Direct Ink Writing for Soft Robotic Applications

Elastic micro-nano structures with complex features (e.g. overhangs, bridges, porous lattices) are vital for soft robotics, flexible sensing, and biomedical devices, yet their fabrication faces challenges of support-material residue and gravitational deformation. This paper presents a support-free direct ink writing 3D printing strategy for elastic silicone microstructures by precisely regulating material yield strength to exceed structural maximum stress. The method enables large-span self-supporting structures (up to 10 mm), including cantilevers and hollow cylinders, without external supports, . A quantitative model links process parameters (speed, pressure, layer height) to line width, and a hyperelastic silicone material with exceptional strain tolerance (514%) and notch resistance is developed. As an application demonstration, flexible sensors are integrated into 3D-printed grippers, enabling real-time feedback during object manipulation. Validated via an industrial robotic arm, the gripper stably handles fragile irregular objects (e.g. eggs and cherry tomatoes) with rapid response(0.6 s). This work establishes a scalable paradigm for manufacturing self-supporting elastic microstructures in soft robotics and precision applications.