3D-Printed Hermetic Alumina Housings

Ink-based additive manufacturing for electrochemical applications

Additive manufacturing (AM), commonly known as three-dimensional (3D) printing, has drawn substantial attention in recent decades due to its efficiency and precise control in part fabrication. The limitations of conventional fabrication processes, especially regarding geometry complexity, supply chain, and environmental impact, have prompted the exploration of diverse AM technologies in electrochemistry. Especially, three ink-based AM techniques, binder jet printing (BJP), direct ink writing (DIW), and Inkjet Printing (IJP), have been extensively applied by numerous research teams to produce electrodes, catalyst scaffolds, supercapacitors, batteries, etc. BJP's versatility in utilizing a wide range of materials as powder feedstock promotes its potential for various electrode and battery applications. DIW and IJP stand out for their ability to handle multi-material manufacturing tasks and deliver high printing resolution. To capture recent advancements in this field, we present a comprehensive review of the applications of BJP, DIW, and IJP techniques in fabricating electrochemical devices and components. This review intends to provide an overview of the process-structure-property relationship in electrochemical materials and components across diverse applications manufactured using AM techniques. We delve into how the significantly improved design freedom over the structure offered by these ink-based AM techniques highlights the performance of electrochemical products. Moreover, we highlight their advantages in terms of material compatibility, geometry control, and cost-effectiveness. In specific cases, we also compare the performance of electrochemical components fabricated using AM and conventional manufacturing methods. Finally, we conclude this review article by offering some insights into the future development in this research field.

Dental Materials Applied to 3D and 4D Printing Technologies: A Review

As computer-aided design and computer-aided manufacturing (CAD/CAM) technologies have matured, three-dimensional (3D) printing materials suitable for dentistry have attracted considerable research interest, owing to their high efficiency and low cost for clinical treatment. Three-dimensional printing technology, also known as additive manufacturing, has developed rapidly over the last forty years, with gradual application in various fields from industry to dental sciences. Four-dimensional (4D) printing, defined as the fabrication of complex spontaneous structures that change over time in response to external stimuli in expected ways, includes the increasingly popular bioprinting. Existing 3D printing materials have varied characteristics and scopes of application; therefore, categorization is required. This review aims to classify, summarize, and discuss dental materials for 3D printing and 4D printing from a clinical perspective. Based on these, this review describes four major materials, i.e., polymers, metals, ceramics, and biomaterials. The manufacturing process of 3D printing and 4D printing materials, their characteristics, applicable printing technologies, and clinical application scope are described in detail. Furthermore, the development of composite materials for 3D printing is the main focus of future research, as combining multiple materials can improve the materials' properties. Updates in material sciences play important roles in dentistry; hence, the emergence of newer materials are expected to promote further innovations in dentistry.

New Partially Water-Soluble Feedstocks for Additive Manufacturing of Ti6Al4V Parts by Material Extrusion

In this work, a process chain for the realization of dense Ti6Al4V parts via different material extrusion methods will be introduced applying eco-friendly partially water-soluble binder systems. In continuation of earlier research, polyethylene glycol (PEG) as a low molecular weight binder component was combined either with poly(vinylbutyral) (PVB) or with poly(methylmethacrylat) (PMMA) as a high molecular weight polymer and investigated with respect to their usability in FFF and FFD. The additional investigation of different surfactants' impact on the rheological behaviour applying shear and oscillation rheology allowed for a final solid Ti6Al4V content of 60 vol%, which is sufficient to achieve after printing, debinding and thermal densification parts with densities better than 99% of the theoretical value. The requirements for usage in medical applications according to ASTM F2885-17 can be fulfilled depending on the processing conditions.

Feedstock Development for Material Extrusion-Based Printing of Ti6Al4V Parts

In this work, a holistic approach for the fabrication of dense Ti6Al4V parts via material extrusion methods (MEX), such as fused filament fabrication (FFF) or fused feedstock deposition (FFD), will be presented. With respect to the requirements of the printing process, a comprehensive investigation of the feedstock development will be described. This covers mainly the amount ratio variation of the main binder components LDPE (low-density polyethylene), HDPE (high-density polyethylene), and wax, characterized by shear and oscillation rheology. Solid content of 60 vol% allowed the 3D printing of even more complex small parts in a reproducible manner. In some cases, the pellet-based FFD seems to be superior to the established FFF. After sintering, a density of 96.6% of theory could be achieved, an additional hot isostatic pressing delivered density values better than 99% of theory. The requirements (mechanical properties, carbon, and oxygen content) for the usage of medical implants (following ASTM F2885-17) were partially fulfilled or shortly missed.

Overcoming Facial Paralysis with an Implantable Actuator for Restoration of Blink

The loss of the ability to blink the eyelid is considered the most severe effect of facial nerve paralysis. The delicate homeostasis of the eye is disrupted, and without frequent intervention, the cornea can become damaged, ultimately resulting in blindness. The psychosocial impact is also significant, with individuals withdrawing from society to hide what they perceive to be a disfigurement. Surgical and engineering interventions have been devised to reanimate blink, however, a solution has yet to be designed which addresses both functional and aesthetic concerns. Here we describe an implantable electromagnetic actuator to restore the capacity to blink. Triggered synchronously with the contralateral eye, and externally modifiable to tailor treatment post-operatively to the individual, this implant restores complete blinking and a natural appearance. Cadaver studies (N=12) have been used to validate the device design, including the form factor and force required to elicit a blink, while a passive in vivo study (N=1) has verified the surgical protocol and recovery.

Printing of Zirconia Parts via Fused Filament Fabrication

In this work, a process chain for the fabrication of dense zirconia parts will be presented covering the individual steps feedstock compounding, 3D printing via Fused Filament Fabrication (FFF) and thermal postprocessing including debinding and sintering. A special focus was set on the comprehensive rheological characterization of the feedstock systems applying high-pressure capillary and oscillation rheometry. The latter allowed the representation of the flow situation especially in the nozzle of the print head with the occurring low-shear stress. Oscillation rheometry enabled the clarification of the surfactant’s concentration, here stearic acid, or more general, the feedstocks composition influence on the resulting feedstock flow behavior. Finally, dense ceramic parts (best values around 99 % of theory) were realized with structural details smaller than 100 µm.

Bending Properties of Lightweight Copper Specimens with Different Infill Patterns Produced by Material Extrusion Additive Manufacturing, Solvent Debinding and Sintering

Material extrusion additive manufacturing (MEX) is a versatile technology for producing complex specimens of polymers, ceramics and metals. Highly-filled filaments composed of a binder system and a high-volume content of sinterable powders are needed to produce ceramic or metal parts. After shaping the parts via MEX, the binder is removed and the specimens are sintered to obtain a dense part of the sintered filler particles. In this article, the applicability of this additive manufacturing process to produce copper specimens is demonstrated. The particular emphasis is on investigating the production of lightweight specimens that retain mechanical properties without increasing their weight. The effect of infill grades and the cover presence on the debinding process and the flexural properties of the sintered parts was studied. It was observed that covers could provide the same flexural strength with a maximum weight reduction of approximately 23%. However, a cover on specimens with less than 100% infill significantly slows down the debinding process. The results demonstrate the applicability of MEX to produce lightweight copper specimens.