Digital Light Processing Research Articles

3D-printed zeolite 13X gyroid monolith adsorbents for CO2 capture

Self-standing 3D-printed gyroid monoliths of zeolite 13X were fabricated for the first time for carbon dioxide adsorption. Gyroid sheet-based triply periodic minimal surface (TPMS) lattices provide high surface area per unit volume, smooth surfaces with no discontinuities, and low pressure drop compared to powder and beads, which are essential in gas adsorption. A photopolymer resin and zeolite 13X powder slurry was 3D-printed by digital light processing followed by debinding to remove the polymer and sintering to diffuse and consolidate the zeolite 13X particles. The sintered adsorbents were mechanically stable, and structural and morphological analyses revealed the interconnected nature of the gyroid cells permitting CO2 molecules to easily diffuse into the printed structure, thus ensuring sufficient adsorbent/adsorbate contact. The gyroid zeolite monoliths reached an equilibrium adsorption capacity of 3.5 mmol g−1 in 77 min at 25 °C and 1 bar, whereas the beads and powder required 96 and 100 min, respectively, while after 20 pressure swing adsorption (PSA) cycles, the zeolite monolith showed sustainable performance compared to the powder. The CO2/N2 selectivity ranged from 328 (at 50 mbar) to 51 (at 1 bar) at 25 °C for the zeolite monolith, whereas the powder exhibited selectivity values in the range of 294 (at 50 mbar) to 33 (at 1 bar). Dynamic breakthrough experiments using CO2/N2 mixtures confirmed the fast kinetics and separation performance of the monoliths, while the pressure drop was also significantly lower than the powder and the beads. The novel topology of the developed self-standing gyroid zeolite monoliths eliminate the need for structuring of powdered adsorbents and exhibit competitive performance, enhanced kinetics and cyclability, and reduced pressure drop toward large-scale carbon capture application.

Fabrication of High-Density Microarchitected Tungsten via DLP 3D Printing.

Current additive manufacturing (AM) techniques for tungsten, such as powder bed fusion and directed energy deposition, often generate parts with rough surfaces. Vat photopolymerization presents a promising alternative for fabricating tungsten structures with high shape fidelity and low surface roughness. However, existing vat photopolymerization approaches suffer from surface defects and low final density, leading to compromised mechanical properties. Therefore, achieving high-density tungsten structures using vat photopolymerization remains a crucial challenge. This work presents a straightforward and reliable method for fabricating complex, micro-architected tungsten structures with superior density and hardness. The approach utilizes a water-based photoresin with exceptional tungsten ion loading capacity. The photoresin is then patterned using digital light processing (DLP) to create tungsten-laden precursors. A three-step debinding and sintering process subsequently achieves 3D tungsten structures with dense surface morphology and minimal internal defects. The microstructures achieve a minimum feature size of 35µm, a low surface roughness of 2.86µm, and demonstrate exceptional mechanical properties. This new method for structuring tungsten opens doors to a broad range of applications, including micromachining, collimators, detectors, and metamaterials.

Bio-based ester- and ester-imine resins for digital light processing 3D printing: The role of the chemical structure on reprocessability and susceptibility to biodegradation under simulated industrial composting conditions

Four biobased ester and ester-imine photocurable resins were formulated and evaluated for printability by digital light processing 3D printing. The resin formulations consisted of methacrylated eugenol alone or in combination with methacrylated poly(hydroxybutyrate)-oligomers and/or methacrylated vanillin-derived Schiff-base monomers. It was not possible to print methacrylated eugenol alone into coherent thermosets, likely due to the lower reactivity of the allyl-double bond. However, in combination with the other building blocks methacrylated eugenol improved the printability, although some over-curing phenomena were registered especially for the resins composed of methacrylated eugenol and methacrylated poly(hydroxybutyrate)-derived oligomers. The three formulations that were successfully printed to coherent thermosets were further evaluated for their solvent resistance, thermal and mechanical properties, reprocessability and biodegradability under simulated industrial composting conditions. The reprocessing experiments documented the synergic effect of ester and imine dynamic covalent bonds in favoring the preservation of the elastic modulus of the thermosets; while an evidently higher deterioration of the mechanical properties was registered for the ester-thermosets. The biodegradation studies highlighted a clear correlation between the biodegradation rate and the chemical structure of the thermosets, with the aliphatic components and ester and imine bonds increasing the thermosets’ susceptibility to the biodegradation under simulated industrial composting conditions.

Mesh Optimisation for General 3D Printed Objects with Cusp-Height Triangulation Approach

3D printing (3DP) is increasingly utilized to achieve quick turnaround on various geometric designs and prototypes, being the growing part of additive manufacturing technology (AMT). The 3DP technique effectively improves the production of complex models in terms of low-cost, time-consuming production, and with less material volume. The key to results optimisation with 3DP is the preparation of the geometry. The following techniques can effectively reduce the required time of the 3D printing process for complex and non-linear CAD files. The fused deposition modelling/fabrication (FDM/FFF) techniques become the first choice in many applications, including biomedical ones. Still, some obstacles exist in the geometry roughness and quality zones. This paper proposes an optimisation method for 3D printed shapes used in biomedical devices and instrumentation by minimising the support structure attached to the model using the FDM technique. In this research, we proposed a method for dynamic compensation against gravity-affected parts extended from the main object’s geometry using a forward planar learning (FPL) algorithm to minimise cusp height in 3D printed objects. After the slicing stage, the outcomes proved to be of good quality, optimised the object’s surfaces, and minimised the printing time by 32%–38%. The proposed method is promising in defining a better setting for slicing and toolpath for FDM 3D printing. However, this method was not tested on other 3DP methods (Stereolithography (SLA), Selective laser sintering (SLS), and Digital Light Processing (DLP)), as more verification efforts need to be done on these 3D printing processes.

Mechanical Properties of Additive-Manufactured Composite-Based Resins for Permanent Indirect Restorations: A Scoping Review.

The introduction of 3D printing technology in dentistry has opened new treatment options. The ongoing development of different materials for these printing purposes has recently enabled the production of definitive indirect restorations via 3D printing. To identify relevant data, a systematic search was conducted in three databases, namely PubMed, Scopus, and Web of Science. Additionally, a manual search using individual search terms was performed. Only English, peer-reviewed articles that encompassed in vitro or in vivo research on the mechanical properties of 3D-printed composite materials were included, provided they met the predefined inclusion and exclusion criteria. After screening 1142 research articles, 14 primary studies were selected. The included studies mainly utilized digital light processing (DLP) technology, less commonly stereolithography (SLA), and once PolyJet printing technology. The material properties of various composite resins, such as VarseoSmile Crown Plus (VSC) and Crowntec (CT), were studied, including Vickers hardness, flexural strength, elastic modulus, compressive strength, tensile strength, fracture resistance, and wear. The studies aimed to compare the behavior of the tested additive composites to each other, conventional composites, and subtractive-manufactured materials. This scoping review examined the mechanical properties of composites used for 3D printing of definitive restorations. The aim was to provide a comprehensive overview of the current knowledge on this topic and identify any gaps for future research. The findings suggest that 3D-printed composites are not yet the first option for indirect restorations, due to their insufficient mechanical properties. Due to limited evidence, more research is needed in this area. Specifically, there is a need for clinical trials and long-term in vivo research.

Photolithographic additive manufacturing of high-entropy perovskite oxides from synthesized multimetallic polymeric precursors

In this work, the synthesis of high-entropy perovskite-type oxides from multimetallic polymeric precursors and their shaping by photolithographic additive manufacturing is investigated. Thermosets with well-controlled complex geometries are produced by digital light processing using the multimetallic organic-inorganic hybrid resin developed in this work and converted into ceramics by thermal debinding and sintering. The high-entropy perovskite-type oxides are produced at 1500 °C, they retain the printed geometry with high shape fidelity. The orthorhombic crystal structure is identified by the Rietveld refinement of high-resolution synchrotron X-ray data; elemental and spectroscopic characterizations suggest the composition Sr(Ti0.22Zr0.22Hf0.23Mn0.15Sn0.18)O2.85. The use of aqueous polyethylene glycol as a binder and porogen greatly reduces the formation of cracks and creates evenly distributed micropores, which leads to improved compressive strength of the specimens. The compressive strength of 0.94 MPa is highest for materials printed from the resins with 3 wt% PEG in the woodpile-like geometries.

Nanoindentation creep: The impact of water and artificial saliva storage on milled and 3D-printed resin composites.

This study evaluated the effects of artificial saliva and distilled water on the nanoindentation creep of different 3D-printed and milled CAD-CAM resin composites. Disk-shaped specimens were subtractively fabricated from polymer-infiltrated ceramic network (EN) and reinforced resin composite (B) and additively from resin composite (C) and hybrid resin composite (VS) using digital light processing (DLP). Specimens from each material were divided into two groups according to their storage conditions (artificial saliva or distilled water for 3 months). Creep was analyzed by nanoindentation testing. Statistical analysis was done using two-way ANOVA, one-way ANOVA, Bonferroni post hoc tests, and independent t-test (α = 0.05). The main effects of material and storage conditions, and their interaction were statistically significant on nanoindentation (p<0.001). Storage condition had the greatest influence (partial eta squared ηP 2 =0.370), followed by the material (ηP 2 = 0.359), and the interaction (ηP 2 = 0.329). The nanoindentation creep depths after artificial saliva storage ranged from 0.34 to 0.51µm and from 0.50 to 0.87µm after distilled water storage. One of the additively manufactured groups had higher nanoindentation creep depths in both storage conditions. All specimens showed comparable performance after artificial saliva storage, but increased nanoindentation creep after distilled water storage for 3 months. The subtractive CAD-CAM blocks showed superior dimensional stability in terms of nanoindentation creep depths in both storage conditions. Additively manufactured composite resins had lower dimensional stability than one of the subtractively manufactured composites, which was demonstrated as having higher creep deformation and maximum recovery. However, after artificial saliva storage, one of the additively manufactured resins had dimensional stability similar to that of subtractively manufactured.

3D-printing inherently MRI-visible accessories in aiding MRI-guided biopsies

Background3D printers have gained prominence in rapid prototyping and viable in creating dimensionally accurate objects that are both safe within a Magnetic Resonance Imaging (MRI) environment and visible in MRI scans. A challenge when making MRI-visible objects using 3D printing is that hard plastics are invisible in standard MRI scans, while fluids are not. So typically, a hollow object will be printed and filled with a liquid that will be visible in MRI scans. This poses an engineering challenge however since objects created using traditional Fused Deposition Modeling (FDM) 3D-printing techniques are prone to leakage. Digital Light Processing (DLP) is a relatively modern and affordable 3D-printing technique using UV-hardened resin, capable of creating objects that are inherently liquid-tight. When printing hollow parts using DLP printers, one typically requires adding drainage holes for uncured liquid resin to escape during the printing process. If this is not done liquid resin will remain inside the object, which in our application is the desired outcome.PurposeWe devised a method to produce an inherently MRI-visible accessory using DLP technology with low dimensional tolerance to facilitate MRI-guided breast biopsies.MethodsBy hollowing out the object without adding drainage holes and tuning printing parameters such as z-lift distance to retain as much uncured liquid resin inside as possible through surface tension, objects that are inherently visible in MRI scans can be created without further post-processing treatment.ResultsObjects created through our method are simple and inexpensive to recreate, have minimal manufacturing steps, and are shown to be dimensionally exact and inherently MRI visible to be directly used in various applications without further treatment.ConclusionOur proposed method of manufacturing objects that are inherently both MRI safe, and MRI visible. The proposed process is simple and does not require additional materials and tools beyond a DLP 3D-printer. With only an inexpensive DLP 3D-printer kit and basic cleaning and sanitation materials found in the hospital, we have demonstrated the viability of our process by successfully creating an object containing fine structures with low spatial tolerances used for MRI-guided breast biopsies.

Efficient Light-Based Bioprinting via Rutin Nanoparticle Photoinhibitor for Advanced Biomedical Applications.

Digital light processing (DLP) bioprinting, known for its high resolution and speed, enables the precise spatial arrangement of biomaterials and has become integral to advancing tissue engineering and regenerative medicine. Nevertheless, inherent light scattering presents significant challenges to the fidelity of the manufactured structures. Herein, we introduce a photoinhibition strategy based on Rutin nanoparticles (Rnps), attenuating the scattering effect through concurrent photoabsorption and free radical reaction. Compared to the widely utilized biocompatible photoabsorber tartrazine (Tar), Rnps-infused bioink enhanced printing speed (1.9×), interlayer homogeneity (58% less overexposure), resolution (38.3% improvement), and print tolerance (3× high-precision range) to minimize trial-and-error. The biocompatible and antioxidative Rnps significantly improved cytocompatibility and exhibited resistance to oxidative stress-induced damage in printed constructs, as demonstrated with human induced pluripotent stem cell-derived endothelial cells (hiPSC-ECs). The related properties of Rnps facilitate the facile fabrication of multimaterial, heterogeneous, and cell-laden biomimetic constructs with intricate structures. The developed photoinhibitor, with its profound adaptability, promises wide biomedical applications tailored to specific biological requirements.

Insights into morphology and mechanical properties of architected interpenetrating aluminum-alumina composites

Additive manufacturing (AM) technologies are unleashing the restrictions imposed by conventional manufacturing, allowing the production of innovative designs tailored to improve properties or performance. AM techniques in ceramic production allow the application of novel designs to ceramic parts, opening new opportunities for combining technologies aiming to obtain architected interpenetrating phase composites (IPCs). In this study, alumina structures with different architectures and Computer Aided Design (CAD) structure porosity oriented unidirectionally or bidirectionally, were fabricated by vat photopolymerization technique, namely Digital Light Processing. Afterwards, these structures were infiltrated with an aluminum alloy through investment casting, thus obtaining aluminum-alumina IPCs. Under compression, the IPCs presented a ductile behavior, conversely to the fragile ceramic counterparts. The IPCs compressive strength and absorbed energy were expressively higher than their ceramic counterparts. Comparing the bidirectional IPCs with the unidirectional ones, a significant increase in compressive strength and absorbed energy was observed, from 36.2% to 42.3% and from 164.8% to 358.1%, respectively, due to the greater amount and interconnection of the metal inside the ceramic structure. This study demonstrates the feasibility of this manufacturing route, combining two distinctive technologies, for the fabrication of metal-ceramic architected IPCs, allowing to tailor their mechanical properties and energy absorption capacity for a given application.

3D-printed Zirconia and Lithium Disilicate in Dentistry and Their Clinical Applications.

The review focuses on the progressive role of 3D-printing in dentistry, particularly emphasizing the use of zirconia-based and lithium disilicate (LS2) -based ceramic materials. Celebrated for their biocompatibility and esthetic resemblance to natural teeth, these materials have shown promising results with high success rates. Digital light processing (DLP) and stereolithography (SLA) have been noted for producing superior 3D-printed ceramic products. Despite facing challenges such as surface defects, mechanical strength limitations, and esthetic inconsistencies, active research is dedicated to refining the quality and esthetics of 3D-printed zirconia-based and LS2-based ceramics. The review acknowledges the need to mitigate the steep costs of this manufacturing form and recognizes the current shortfall in clinician and technician awareness of these advanced techniques. Addressing these issues through focused research on improving surface quality, dimensional accuracy, and mechanical properties of 3D-printed dental prostheses is crucial, as is enhancing the dental community's understanding and acceptance of this innovative technology.

Abstract We007: High Throughput 3D-Printed Human Engineered Heart Tissues for Cardiac Disease Modeling

While cell models have been used to study cardiac diseases, there is currently no standardization or fully mature in vitro system. Obtaining a mature cardiomyocyte (CM) phenotype is necessary to create a physiologically relevant environment and accurately model and study cardiac diseases. Increased success in maturation of human induced pluripotent stem cell derived CMs (hiPS-CMs) has been achieved in 3D in vitro models in the form of engineered heart tissues (EHTs). Digital light processing (DLP) offers a high throughput and efficient method to fabricate hydrogels that recapitulate properties of native tissues. In this study, we use DLP-printed EHTs to seed and mature differentiated hiPS-CMs and test their potential for modeling pathological cardiac hypertrophy. To further encourage maturity of CMs, we utilized a low glucose maturation medium supplemented with fatty acids. DLP-printed EHTs displayed high reproducibility and increased CM maturity. To determine degree of maturity of our system, we performed RT-qPCR, western blot analysis, and immunofluorescence (IF) microscopy. We found increased expression of fatty-acid transport and beta oxidation genes and improved sarcomere alignment compared to 2D hiPS-CMs. To model pathological cardiac hypertrophy, we used two different approaches: 1. acute adrenergic agonism with isoproterenol and phenylephrine; 2. chronic culturing of EHTs in pathologically stiff conditions. To assess pathology, we conducted RT-qPCR, western blot, ELISA, IF microscopy, and functional analyses. We found that agonist-treated EHTs displayed increased pathology-associated gene expression compared to standard 2D hiPS-CMs. Both agonist-treated and stiff EHTs had increased secreted B-Type Natriuretic Peptide (BNP) and phosphorylation of proteins involved in pathological remodeling, including ERK and P38. Additionally, we observed increased nuclear area, increased calcium handling, and increased contractile force in the treatment groups. In conclusion, we have established a high throughput, reproducible, mature EHT platform that can be used to model pathological cardiac hypertrophy. This platform can be easily adopted by other laboratories to study a wide array of cardiac diseases.

Additive manufacturing of highly entangled polymer networks.

Incorporation of polymer chain entanglements within a single network can synergistically improve stiffness and toughness, yet attaining such dense entanglements through vat photopolymerization additive manufacturing [e.g., digital light processing (DLP)] remains elusive. We report a facile strategy that combines light and dark polymerization to allow constituent polymer chains to densely entangle as they form within printed structures. This generalizable approach reaches high monomer conversion at room temperature without the need for additional stimuli, such as light or heat after printing, and enables additive manufacturing of highly entangled hydrogels and elastomers that exhibit fourfold- to sevenfold-higher extension energies in comparison to that of traditional DLP. We used this method to print high-resolution and multimaterial structures with features such as spatially programmed adhesion to wet tissues.

Effect of ZrO2 content on mechanical properties of SiC ceramics prepared based on digital light processing

Digital light processing (DLP) technology shows promise in addressing the challenges of preparing high-strength, precise, and complex SiC ceramic structural parts. However, the low strength of DLP-printed SiC ceramic parts remains a persistent issue. To address this, a nano-ZrO2 particle enhancement strategy is proposed. This study systematically investigates the effects of ZrO2 content on slurry viscosity, curing depth, microscopic morphology, and the mechanical properties of SiC ceramics. The results indicate that increasing the ZrO2 content raises the viscosity of the SiC slurry and decreases the curing depth, which can adversely affect the printing quality of SiC ceramic green bodies. However, a higher ZrO2 content significantly reduces pore defects in the sintered parts, improving densification and mechanical properties. This underscores the importance of optimizing ZrO2 content. The SiC sintered parts reinforced with ZrO2 particles exhibited outstanding properties, including a relative density of 91.1 ± 3.2 %, Vickers hardness of 996.4 ± 93.8 HV, and a flexural strength of 201.5 ± 11.4 MPa. This study provides a straightforward and effective method for producing high-strength SiC ceramics via DLP.

Enhanced molding and mechanical properties of SiC-based ceramic lattice structures via digital light processing

Silicon carbide (SiC) ceramic lattice structures (CLSs) hold significant potential for use in structural components and optical mirrors in space exploration due to their light weight, high strength, and excellent dimensional stability. However, they face challenges such as poor curing performance and weak mechanical strength during the digital light processing (DLP) additive manufacturing process. In this study, SiC@Al2O3 powder was prepared, resulting in a 21% reduction in absorptivity compared to bare SiC powder. The ceramic paste derived from this powder achieved a curing thickness of up to 80 μm, exhibited a reduced over-curing width, and demonstrated a 75% improvement in stability compared to bare SiC paste. Consequently, high-quality triply periodic minimal surfaces (TMPS) structured SiC@Al2O3 CLSs green bodies were successfully fabricated. By integrating precursor impregnation pyrolysis with the reaction melting infiltration (PIP-RMI) post-treatment densification method, SiC@Al2O3/Si CLSs were produced, exhibiting superior mechanical properties with low dimensional shrinkage. At 30% volume fraction, the specific compressive strength of the primitive-TPMS SiC@Al2O3/Si CLSs reached 24.79 MPa. This study presents an effective method for fabricating SiC-based ceramic CLSs and establishes a foundation for the optimization of SiC ceramic fabrication processes.

Piezoelectric properties and biocompatibility of barium titanate prepared via digital light processing

Barium titanate (BT) is widely studied in bone repair engineering due to its high dielectric constant, excellent ferroelectric properties, and non-toxic nature. However, one of the research focuses on the preparation of high-precision BT ceramics and enhances their limited mineralization bioactivity. BT is difficult to use for high-precision ceramic molding using Digital Light Processing (DLP) due to its high refractive index and strong ultraviolet absorption. In this manuscript, BT was doped with calcium silicate (CS) which has a refractive index close to photosensitive resin. The printing parameters of the composite ceramic scaffolds were determined to obtain a balance between printing efficiency and accuracy. Experimental results have demonstrated that within a CS doping ratio of up to 20 wt%, the scaffolds simultaneously meet the piezoelectric coefficient and mechanical properties of natural bone. Furthermore, mineralization and cell experiments have shown that the composite scaffold exhibits improved degradation rate, cell activity, and osteoinductivity. Subsequently, bone scaffolds with a doping ratio of 20 wt% were selected, which meet the requirements of natural bone and exhibit significantly enhanced biological activity. Research findings revealed that ceramic scaffolds after piezoelectric stimulation are more conducive to cell proliferation and growth compared to before stimulation.

Particle grading and debinding process of zirconia ceramic based on digital light process

Digital light processing technology has the advantages of high molding accuracy and the ability to prepare complex structures, which is commonly used in the preparation of resin or ceramics. By mixing two particle sizes of zirconia powders, this paper successfully prepared a 60 vol% slurry with a low viscosity of 1.28 Pa s at shear rate was 50 s−1. By systematically studying the rheological properties of the mixed slurry, the curing depth was exceeding 100 μm at exposure time of 3 s. Furthermore, by investigating the debinding process of the printed sample, it is found that the sintering sample after debinding in vacuum has the highest density. This work has a positive significance for the preparation and debinding process of high solid loading ceramic slurry.

Parametric design and performance evaluation of TPMS porous vitrified bond diamond grinding wheel using digital light processing

Porous vitrified bond diamond grinding wheels are commonly used for grinding hard and brittle materials. However, uneven pore distribution and low porosity affect the grinding performance of the wheel significantly. In this study, three types of triply periodic minimal surface porous vitrified bond diamond grinding wheels—Gyroid, Diamond, and Lidinoid–were prepared through parametric designing and digital light processing 3D printing. The grinding wheel achieved a uniform distribution and an interconnected pore structure. The key to high-performance grinding wheel via stereolithography 3D printing lies in the preparation of the slurry with high solid loading, low viscosity and uniform stability. Hence, the effect of surface modifiers on the slurry, along with the effect of sintering temperature and the microscopic and mechanical properties, was investigated. By grinding the SiC ceramics, the material removal rate, grinding temperature, and surface roughness were compared to those achieved using a conventional solid-structure grinding wheel. The results show that the slurry with the highest solid content of 80 wt% (58 vol%) and viscosity of 4.21 Pa s (30 s−1) can be prepared using surface-modified particles. The diamond grinding wheel sintered at 680 °C exhibits the best comprehensive performance. A grinding wheel prepared using stereolithography 3D printing can achieve better surface roughness and lower the grinding temperature.

A novel mullite anti-gyroid/SiC gyroid ceramic metastructure based on digital light processing 3D printing with enhanced electromagnetic wave absorption and mechanical properties

A novel mullite anti-gyroid/SiC gyroid ceramic metastructure based on digital light processing 3D printing with enhanced electromagnetic wave absorption and mechanical properties

Matrix design for optimal pancreatic β cells transplantation

New therapeutic approaches to treat type 1 diabetes mellitus relies on pancreatic islet transplantation. Here, developing immuno-isolation strategies is essential to eliminate the need for systemic immunosuppression after pancreatic islet grafts. A solution is the macro-encapsulation of grafts in semipermeable matrixes with a double function: separating islets from host immune cells and facilitating the diffusion of insulin, glucose, and other metabolites.This study aims to synthesize and characterize different types of gelatin-collagen matrixes to prepare a macro-encapsulation device for pancreatic islets that fulfill these functions. While natural polymers exhibit superior biocompatibility compared to synthetic ones, their mechanical properties are challenging to reproduce. To address this issue, we conducted a comparative analysis between photo-crosslinked gelatin matrixes and chemically crosslinked collagen matrixes. We show that the different crosslinkers and polymerization methods influence the survival and glucose-stimulated insulin production of pancreatic β cells (INS1) in vitro, as well as the in vitro and in vivo stability of the matrix and the immuno-isolation in vivo.Among the matrixes, the stiff multilayer GelMA matrixes (8.5 kPa), fabricated by digital light processing, were the best suited for pancreatic β cells macro-encapsulation regarding these parameters. Within the alveoli of this matrix, pancreatic β cells spontaneously formed aggregates.