Embedded Core–Shell 3D Printing (eCS3DP) with Low-Viscosity Polysiloxanes

Abstract

Flexible core–shell 3D structures are essential for the development of soft sensors and actuators. Despite recent advancements in 3D printing, the fabrication of flexible 3D objects with internal architectures (such as channels and void spaces) remains challenging with liquid precursors due to the difficulty to maintain the printed structures. The difficulty of such fabrication is prominent especially when low-viscosity polysiloxane resins are used. This study presents a unique approach to applying direct ink writing (DIW) 3D printing in a three-phase system to overcome this limitation. We performed core–shell 3D printing using a low-viscosity commercial polysiloxane resin (Ecoflex 10) as shell inks combined with a coaxially extruded core liquid (Pluronic F127) in Bingham plastic microparticulate gels (ethanol gel). In the process termed embedded core–shell 3D printing (eCS3DP), we highlighted the dependence of the rheological characteristics of the three fluids on the stability of the printed core–shell filament. With the core liquid with a sufficiently high concentration of Pluronic F127 (30 w/w%; σy = 158.5 Pa), the interfacial instability between the shell liquid and core liquid was suppressed; the removal of the core liquid permitted the fabrication of perfusable channels. We identified the printing conditions to ensure lateral attachments of printed core–shell filaments. Interestingly, judicious selection of the rheological properties and flow rates of three phases allowed the formation of droplets consisting of core liquids distributed along the printed filaments. eCS3DP offers a simple route to fabricate 3D structures of a soft elastomeric matrix with embedded channels and should serve as a useful tool for DIW-based fabrication of flexible wearable devices and soft robotic components.

Core–Shell Filament with Excellent Wound Healing Property Made of Cellulose Nanofibrils and Guar Gum via Interfacial Polyelectrolyte Complexation Spinning

“…[1,2] They were employed to prepare functional materials for drug delivery, humidity sensor, antireflection coatings, etc. Generally, these filaments were prepared using coaxial wet spinning, [3,4] coaxial electrospinning, [5] interfacial polyelectrolyte complexation (IPC), water-evaporationcontrolled self-assembly, [6] 3D printing, [2] and surface-modification of filaments. [7,8] Compared with other spinning methods, IPC spinning, firstly reported by Yamamoto et al in 1998, is a facile and eco-friendly method without dedicated devices.…”

“…In recent years, core-shell filaments have attracted more and more attention due to their unique structure and properties. [1,2] They were employed to prepare functional materials for drug delivery, humidity sensor, antireflection coatings, etc. Generally, these filaments were prepared using coaxial wet spinning, [3,4] coaxial electrospinning, [5] interfacial polyelectrolyte complexation (IPC), water-evaporationcontrolled self-assembly, [6] 3D printing, [2] and surface-modification of filaments.…”

Nanomaterials-Based Hybrid Bioink Platforms in Advancing 3D Bioprinting Technologies for Regenerative Medicine

“…5,20 Polylactic Acid (PLA), a hydrolytic degradable, 52 aliphatic polyester, owing to its biocompatibility, degradability, and 3D printing potential, has emerged as a popular polymeric bioink for tissue engineering applications. 20,52 Recently, Karyappa et al 164 and Dave et al 165 studied a hybrid bioink based on PLA and printed 3D complex structure. Consequently, it could potentially be a candidate for bone tissue regeneration.…”

Hydrogels for 3D bioprinting in tissue engineering and regenerative medicine: Current progress and challenges

“…Pluronic F127 is usually used as 215 a sacrificial material for constructing hollow blood vessel channels to simulate bionic blood vessels in the bioprinting of tissue engineering [ 82 , 83 ] . Karyappa et al [ 84 ] used a low- viscosity, commercial polysiloxane resin (Ecoflex 10) as shell inks in conjunction with a coaxially extruded core fluid (Pluronic F127) for core–shell 3D printing in a Bingham plastic microparticle gels (ethanol gel). They wisely selected appropriate rheological properties and flow rates of the three phases, which allowed the formation of droplets composed of a core liquid distributed along the printed filament.…”