Object-space optimization of tomographic reconstructions for additive manufacturing

Rackson, Charles M.; Champley, Kyle; Toombs, Joseph; Fong, Erika J.; Bansal, Vishal; Taylor, Hayden; Shusteff, Maxim; McLeod, Robert R.

doi:10.1016/j.addma.2021.102367

Cited by 26 publications

(28 citation statements)

References 29 publications

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“…Digital light projections were computed and optimized with the object‐space model optimization algorithm [ 41 ] using forward and inverse models which account for light occlusion by the insert [ 42 ] (Figure 5b). The insert was suspended in the gel (Figure 5c) in a two‐step process: first, a small amount of liquefied 7 wt% gel was dispensed into the container and allowed to cool; second, the insert was embedded in the gel and more liquefied gel was dispensed to cover the insert completely.…”

Section: Resultsmentioning

confidence: 99%

Ethyl Cellulose‐Based Thermoreversible Organogel Photoresist for Sedimentation‐Free Volumetric Additive Manufacturing

Toombs

Shan

Taylor

2023

Macromol. Rapid Commun.

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Liquid photoresists are abundant in the field of light‐based additive manufacturing (AM). However, printing unsupported directly into a vat of material in emerging volumetric AM technologies―typically a benefit due to fewer geometric constraints and less material waste―can be a limitation when printing low‐viscosity liquid monomers and multimaterial constructs due to part drift or sedimentation. With ethyl cellulose (EC), a thermoplastic soluble in organic liquids, a simple three‐component transparent thermoreversible gel photoresist with melting temperature of ≈64 °C is formulated. The physically crosslinked network of the gel leads to storage moduli in the range of 0.1−10 kPa and maximum yield stress of 2.7 kPa for a 10 wt% EC gel photoresist. Nonzero yield stress enables sedimentation‐free tomographic volumetric patterning in low‐viscosity monomer without additional hardware or modification of apparatus. In addition, objects inserted into the print container can be suspended in the gel material which enables overprinting of multimaterial devices without anchors connecting the object to the printing container. Flexural strength is also improved by 100% compared to the neat monomer for a formulation with 7 wt% EC.

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Section: Resultsmentioning

confidence: 99%

Ethyl Cellulose‐Based Thermoreversible Organogel Photoresist for Sedimentation‐Free Volumetric Additive Manufacturing

Toombs

Shan

Taylor

2023

Macromol. Rapid Commun.

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“…[ 7 , 9 ] As any projection‐based printing system, the final resolution of the printed structure is theoretically determined by the effective pixel size of the DMD at the center of the build volume. Gray‐scale tomographic reconstruction algorithms have been used to improve print resolution [ 12 , 17 ] or print stiffness. [ 14 ] In practice, the final resolution of the prints is also affected by the polymerization process of the resin and potential optical aberrations inherent to the experimental setup.…”

Section: Introductionmentioning

confidence: 99%

Controlling Light in Scattering Materials for Volumetric Additive Manufacturing

et al. 2022

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3D printing has revolutionized the manufacturing of volumetric components and structures in many areas. Several fully volumetric light‐based techniques have been recently developed thanks to the advent of photocurable resins, promising to reach unprecedented short print time (down to a few tens of seconds) while keeping a good resolution (around 100 μm). However, these new approaches only work with homogeneous and relatively transparent resins so that the light patterns used for photo‐polymerization are not scrambled along their propagation. Herein, a method that takes into account light scattering in the resin prior to computing projection patterns is proposed. Using a tomographic volumetric printer, it is experimentally demonstrated that implementation of this correction is critical when printing objects whose size exceeds the scattering mean free path. To show the broad applicability of the technique, functional objects of high print fidelity are fabricated in hard organic scattering acrylates and soft cell‐laden hydrogels (at 4 million cells mL −1 ). This opens up promising perspectives in printing inside turbid materials with particular interesting applications for bioprinting cell‐laden constructs.

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“…The goodness of the algorithm is essential to produce patterns whose back-projections form a volumetric dose of light that best represents the target object inside the resin. Several recent works have been proposed to optimize the set of patterns with respect to (1) the target dose by including physics priors 18,19 or (2) more appropriate loss functions that enhance contrast 20 . With regard to the resin's opacity, it is clear that optically transparent materials allow for propagating sharp patterns of high-fidelity, but the same patterns would be inevitably blurred and thus lose its finest features in scattering media.…”

Section: Introductionmentioning

confidence: 99%

Volumetric helical additive manufacturing

Boniface¹,

Maître²,

Madrid‐Wolff³

et al. 2023

gxjzz

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3D printing has revolutionized the manufacturing of volumetric components and structures for various fields. Thanks to the advent of photocurable resins, several fully volumetric light-based techniques have been recently developed to push further the current limitations of 3D printing. Although fast, this new generation of printers cannot fabricate objects whose typical size exceeds the centimeter without severely affecting the final resolution. Based on tomographic volumetric additive manufacturing, we propose a method for volumetric helical additive manufacturing (VHAM) multi-cm scale structures without magnifying the projected patterns. It consists of illuminating the photoresist while the latter follows a helical motion. This movement allows to increase the printable object's height. Additionally, we off-center the modulator used for projecting the light patterns to double the object's lateral size. We demonstrate experimentally the interest of using these two tricks for printing larger objects (up to 3 cm × 3 cm × 5 cm) with fine details (650 μm) and short print time (< 10 min).

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Object-space optimization of tomographic reconstructions for additive manufacturing

Cited by 26 publications

References 29 publications

Ethyl Cellulose‐Based Thermoreversible Organogel Photoresist for Sedimentation‐Free Volumetric Additive Manufacturing

Ethyl Cellulose‐Based Thermoreversible Organogel Photoresist for Sedimentation‐Free Volumetric Additive Manufacturing

Controlling Light in Scattering Materials for Volumetric Additive Manufacturing

Volumetric helical additive manufacturing

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