Phase‐Change‐Enabled, Rapid, High‐Resolution Direct Ink Writing of Soft Silicone

Abstract

Soft silicone is an ideal flexible material for application, e.g., in soft robotics, flexible electronics, bionics, or implantable biomedical devices. However, gravity‐driven sagging, filament stretching, and deformation can cause inevitable defects during rapid manufacturing, making it hard to obtain complex, high‐resolution 3D silicone structures with direct ink writing (DIW) technology. Here, rapid DIW of soft silicone enabled by a phase‐change‐induced, reversible change of the ink's hierarchical microstructure is presented. During printing, the silicone‐based ink, containing silica nanoparticles and wax microparticles, is extruded from a heated nozzle into a cold environment under controlled stress. The wax phase change (solid–liquid–solid) during printing rapidly destroys and rebuilds the particle networks, realizing fast control of the ink flow behavior and printability. This high‐operating‐temperature DIW method is fast (maximum speed ≈3100 mm min−1) and extends the DIW scale range of soft silicone. The extruded filaments have small diameters (50 ± 5 µm), and allow for large spans (≈13‐fold filament diameter) and high aspect ratios (≈1), setting a new benchmark in the DIW of soft silicone. Printed silicone structures exhibit excellent performance as flexible sensors, superhydrophobic surfaces, and shape‐memory bionic devices, illustrating the potential of the new 3D printing strategy.

MXene‐Based Flexible Sensors: Materials, Preparation, and Applications

“…Printing methods typically print MXene-based inks directly onto a flexible substrate material to form a functional sensor. Screen printing, [177] ink writing, [178] and 3D printing, [179] all belong to the family of printing method. Yang et al [172] used sodium ascorbate (SA) and MXene to prepare an SA-MXene ink, which was then printed directly onto a paper-based substrate material by screen printing to form a flexible sensor (Figure 9g).…”

3D Printed Silicones with Shape Morphing and Low-Temperature Ultraelasticity

“…The rising three-dimensional (3D) printing technique, with its unparalleled freedom to create complex, customized geometries with low cost, shows great promise in controlling the internal morphologies and architectures of cellular materials. − Especially, 3D printing of silicones could be realized using direct ink writing (DIW), ,,,− inkjet printing, , embedded 3D printing, , vat polymerization, , and expanded techniques for higher resolution. , Mechanical responses of the printed foams could be well predicted, designed, and/or optimized by digital techniques such as simulation and machine learning , and further tailored by controlling the inner structure (such as the polymer network , and filler orientation , ) of the printed filaments. In addition, by introducing micro- or nanoscale pores in the 3D printed filaments using a sacrificial templating concept, − a hierarchical porous structure could be achieved, endowing the foam with ultraelasticity (i.e., extreme compressibility and cyclic endurance) and much enhanced active surface area compared to its nonhierarchical counterparts, , which is favorable for high-tech fields such as aerospace, energy, and bioengineering.…”

Multinozzle 3D Printing of Multilayer and Thin Flexible Electronics

“…3D printing is an effective method for fabricating multilayer flexible electronics. [35] At present, 3D printing technologies for fabricating multilayer flexible electronics mainly include inkjet printing, [36][37][38] material extrusion, [39,40] direct ink writing, [41][42][43] and nanodimensions PCB printer. [44] These 3D printing technologies can fabricate multilayer flexible electronics, but require the coordination of multiple processes, which still poses great challenges for multilayer fabrication.…”