A hybrid exposure concept for lithography-based additive manufacturing

Busetti, Bernhard; Steyrer, Bernhard; Lutzer, Bernhard; Reiter, R.; Stampfl, Jürgen

doi:10.1016/j.addma.2018.03.024

Cited by 13 publications

(7 citation statements)

References 20 publications

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“…The bio-ink should be tailored to the printer such that VPP systems can be divided into vector-and pixel-based systems. 59 The vector-based approach (SLA and 2PP) fabricates through the exposure of continuous lines that map the contour of each print layer. To form the complete product, the laser hatches across the cross-sectional area.…”

Section: Vat Photopolymerizationmentioning

confidence: 99%

“…A major advantage of such system is that the exposure time is independent on the size of the cross-sectional area. 59 The light-polymer interaction in VPP involves two steps, namely, photophysical and photochemical processes. These processes are described in detail in Ref.…”

Section: Vat Photopolymerizationmentioning

confidence: 99%

“…In a DLP system, where light projection is used instead of the laser beam, E DLP is used instead of E max when describing the penetration depth. 59 The exposure energy in DLP is dependent on the light intensity of the DLP system I and exposure time t E , E DLP ¼ IÃt E .…”

Section: Vat Photopolymerizationmentioning

confidence: 99%

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Resolution and shape in bioprinting: Strategizing towards complex tissue and organ printing

Lee

Yeong

2019

Applied Physics Reviews

117

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In 3D bioprinting, printing resolution represents the deposited material in the x-and y-axes, while dimensionality defines the structural resolution of printed constructs. Dimensionality in 3D bioprinting can be defined as the resolution in the z-axis. The printing resolution, together with dimensionality, contributes to the overall shape fidelity of the bioprinted constructs. The in-depth understanding of physical processes for different printing technologies is imperative in controlling the print resolution and definition. In this article, bioprinting technologies are classified according to the physical processes that deposit or form the bioprinted construct. Due to the different fabrication processes in forming fundamental printed units (voxels), the definition of printability differs for each bioprinting technique. Another aspect of resolution is the spatial positioning of cells within each fundamental building unit. The proximity of cells in the bioprinted construct affects the physiological outcomes. The second aspect of 3D bioprinting technologies is the ability to control shape fidelity. Different strategies have been used to improve the construction of a 3D engineered tissue or organ. Lastly, moving toward complex tissue printing involves adding functionalities to the bioprinted construct. Data processing, material formulations, and integration of different fabrication technologies are key areas in bioprinting that can recapture the different hierarchical aspects of native tissues. This article presents a comprehensive overview of enhancing the resolution of the bioprinting construct and identifying methods to improve functionalities of bioprinted tissues.

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Section: Vat Photopolymerizationmentioning

confidence: 99%

Section: Vat Photopolymerizationmentioning

confidence: 99%

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Resolution and shape in bioprinting: Strategizing towards complex tissue and organ printing

Lee

Yeong

2019

Applied Physics Reviews

117

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“…The mentioned power is reduced to 6W at the wavelength ranging from 363 nm to 400 nm. If it uses to project a 30-inch image, the pixel size increases to 250 µm due to the fixed ratio of pixel size to image projection ratio [ 128 ]. However, a pixel size of 158 μm is available in a 10-megapixel 30-inch LCD monochrome panel at a lower cost.…”

Section: Challenges With High-speed Vpp Image Projection Systemsmentioning

confidence: 99%

A Review of Critical Issues in High-Speed Vat Photopolymerization

et al. 2023

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Vat photopolymerization (VPP) is an effective additive manufacturing (AM) process known for its high dimensional accuracy and excellent surface finish. It employs vector scanning and mask projection techniques to cure photopolymer resin at a specific wavelength. Among the mask projection methods, digital light processing (DLP) and liquid crystal display (LCD) VPP have gained significant popularity in various industries. To upgrade DLP and LCC VPP into a high-speed process, increasing both the printing speed and projection area in terms of the volumetric print rate is crucial. However, challenges arise, such as the high separation force between the cured part and the interface and a longer resin refilling time. Additionally, the divergence of the light-emitting diode (LED) makes controlling the irradiance homogeneity of large-sized LCD panels difficult, while low transmission rates of near ultraviolet (NUV) impact the processing time of LCD VPP. Furthermore, limitations in light intensity and fixed pixel ratios of digital micromirror devices (DMDs) constrain the increase in the projection area of DLP VPP. This paper identifies these critical issues and provides detailed reviews of available solutions, aiming to guide future research towards developing a more productive and cost-effective high-speed VPP in terms of the high volumetric print rate.

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“…The first category of the strategies is to combine n × m projects to cover an increased projection area or to combine two light sources with fabrication capabilities at different scales. For example, a projector [26,27] or a laser with a large spot size [28,29] (e.g., 800 µm) is utilized to fabricate the interior of each layer. A laser with a tiny spot size (e.g., 30 µm) is used to cure the contours and microscale features.…”

Section: Related Workmentioning

confidence: 99%

Hopping Light Vat Photopolymerization for Multiscale Fabrication

Mao

Liu

et al. 2022

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3D objects with features spanning from microscale to macroscale have various applications. However, the fabrication of such objects presents challenges to additive manufacturing (AM) due to the tradeoffs among manufacturable feature resolution, maximum build area, and printing speed. This paper presents a projection‐based AM process called hopping light vat photopolymerization (HL‐VPP) to address this critical barrier. The key idea of HL‐VPP is to synchronize linear scanning projection with a galvo mirror's rotation. The projector moves continuously at a constant speed while periodically rotating a one‐axis galvo mirror to compensate for the projector's linear movement so synchronized hopping motion can be achieved. By this means, HL‐VPP can simultaneously achieve large‐area (over 200 mm), fast‐speed (scanning speed of 13.5 mm s‐1), and high‐resolution (10 µm pixel size) fabrication. The distinguishing characteristic of HL‐VPP is that it allows for hundreds of times lower refresh rates without motion blur. Thus, HL‐VPP decouples the fabrication efficiency limit imposed by the refresh rate and will enable super‐fast curing in the future. This work will significantly advance VPP's use in applications that require macroscale part size with microscale features. The process has been verified by fabricating multiple multiscale objects, including microgrids and biomimetic structures.

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A hybrid exposure concept for lithography-based additive manufacturing

Cited by 13 publications

References 20 publications

Resolution and shape in bioprinting: Strategizing towards complex tissue and organ printing

Resolution and shape in bioprinting: Strategizing towards complex tissue and organ printing

A Review of Critical Issues in High-Speed Vat Photopolymerization

Hopping Light Vat Photopolymerization for Multiscale Fabrication

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