Shefi, Orit

AbstractFunctionally gradient materials emulate nature's ability to seamlessly blend properties through variations in material composition, unlocking advanced engineering applications such as biomedical devices and high‐performance composites. Additive manufacturing, particularly stereolithography, enables sophisticated 3D geometries with diverse materials. However, current stereolithography‐based multi‐material 3D printing is constrained by time‐intensive material switching and compromised interfacial properties. To overcome these challenges, we present dynamic fluid‐assisted micro continuous liquid interface production (DF‐µCLIP), a high‐speed multi‐material 3D printing platform that integrates varying compositions in a fully continuous fashion. By utilizing the polymerization‐free “dead zone”, vliquid resins are seamlessly replenished within a resin bath equipped with dynamic fluidic channels and a synchronized material supply system. DF‐µCLIP achieves ultra‐fast printing speeds of 90 mm/hour with 7.4 µ m pixel‐1 resolution while enabling on‐the‐fly material transitions. This strategy enhances mechanical strength at multi‐material interface through entangled polymer networks and promotes seamless material transitions between distinct materials ilike fragile hydrogels and rigid polymers, addressing interfacial failure caused by mismatch of swelling behavior. Additionally, dynamic material replenishment with real‐time composition control enables continuous gradient printing instead of the conventional step‐wise controlled gradient. Demonstrations include polymers with gradient color transitions and gradient carbon nanotube (CNT) composites with seamlessly varying conductivity.

AbstractPelvic organ prolapse (POP) is a dysfunction that affects a large proportion of women. Current support scaffolds’ lack of biocompatibility, biodegradability, and mechanical compliance are associated with surgical complications including erosion and pain, indicating the urgent need for new tissue scaffolds with customizable functions. A new material that uses polyvinyl alcohol (PVA) as the main ingredient and is chemically tuned to possess suitable mechanical properties and degradation rates for the surgical treatment of POP is developed. Specifically, the thiol‐norbornene “click” chemistry enables the sol‐gel transition of the biomaterial under UV‐light without side‐products. Meanwhile, NaOH treatment further toughens the hydrogel with a higher crosslink density. The PVA‐based biocompatible ink can be printed with UV‐facilitated direct ink writing due to the rapidly UV‐initiated chemical crosslink; in situ image analysis and machine learning methods are applied during this procedure to quantify and improve the printing quality. The cell viability results demonstrate the biocompatibility of the POP scaffolds, suggesting the potential for future animal studies and the possibility of clinical research. This study bridges polymer chemistry and manufacturing engineering with a specific tissue engineering application to solve the common disorder of POP, shedding light on individualized medicine and intelligent systems for biomedical engineering.

Abstract3D printing (additive manufacturing (AM)) has enormous potential for rapid tooling and mass production due to its design flexibility and significant reduction of the timeline from design to manufacturing. The current state‐of‐the‐art in 3D printing focuses on material manufacturability and engineering applications. However, there still exists the bottleneck of low printing resolution and processing rates, especially when nanomaterials need tailorable orders at different scales. An interesting phenomenon is the preferential alignment of nanoparticles that enhance material properties. Therefore, this review emphasizes the landscape of nanoparticle alignment in the context of 3D printing. Herein, a brief overview of 3D printing is provided, followed by a comprehensive summary of the 3D printing‐enabled nanoparticle alignment in well‐established and in‐house customized 3D printing mechanisms that can lead to selective deposition and preferential orientation of nanoparticles. Subsequently, it is listed that typical applications that utilized the properties of ordered nanoparticles (e.g., structural composites, heat conductors, chemo‐resistive sensors, engineered surfaces, tissue scaffolds, and actuators based on structural and functional property improvement). This review's emphasis is on the particle alignment methodology and the performance of composites incorporating aligned nanoparticles. In the end, significant limitations of current 3D printing techniques are identified together with future perspectives.