Two-Wavelength Vat Photopolymerization for Lateral Cure Confinement
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Solution Overview
Problem
Existing photopolymerization additive manufacturing (PAM) technologies face challenges in achieving high-fidelity, high-resolution 3D printing with precise lateral feature sizes and resolutions due to issues with residual curing and geometric distortion, particularly in single photon absorption PAM (SPP-AM), which lack effective methods to control lateral photopolymerization and result in mechanical weakness and dimensional inaccuracies.
Innovation Solution
The SPA2CurbCure method employs a two-wavelength irradiation system with a photo-curing and photo-curbing exposure to confine photopolymerization laterally, using photo-inhibition mechanisms to control the curing process, combined with a smart build chamber and real-time material regulation to minimize residual curing and enhance geometric fidelity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If single photon absorption PAM is used to achieve fast 3D printing, then productivity is improved, but manufacturing precision deteriorates due to geometric distortion and loss of resolution
Solution Approach 1:
The patent divides the single curing process into two separate processes: photo-curing and photo-curbing. The photo-curing process deposits the cross-section, while the photo-curbing process removes unwanted lateral polymerization. This segmentation allows each process to be optimized independently, maintaining fast build speeds while improving lateral resolution to below 50 μm.
Solution Approach 2:
The patent introduces a photo-curbing exposure as an intermediary process between photo-curing and the formation of the next cross-section. This intermediate step uses a curbing mask to generate a curbing pattern that laterally confines the photo-curing, removing residual active species at the boundaries and preventing over-polymerization, thereby achieving high lateral resolution without sacrificing productivity.
2Manufacturing precision
If photo-curing exposure is increased to achieve small feature sizes, then manufacturing precision is improved, but object-generated harmful factors worsen due to over-curing and dark-curing
Solution Approach 1:
The patent applies preliminary anti-action by introducing photo-curbing exposure before the photo-curing process completes. The curbing pattern is generated in advance to counteract the unwanted lateral polymerization that would otherwise occur during photo-curing. This preliminary anti-action removes residual active species at the boundaries, preventing over-curing and dark-curing effects while enabling precise feature size control.
3Strength
If conventional PAM is used to achieve high crosslinking density, then strength is improved, but manufacturing precision deteriorates due to residual curing effects
Solution Approach 1:
The patent introduces photo-curbing as an intermediary process that selectively removes residual active species at the boundaries of cured regions. This intermediary step prevents over-polymerization and dark-curing that would otherwise distort geometric features, while the bulk crosslinking density remains high, preserving mechanical strength. The result is high geometric fidelity with maintained strength.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the production of 3D objects with precise lateral resolutions and mechanical strength, overcoming limitations of conventional PAM by achieving feature sizes and resolutions below 50 μm with improved geometric accuracy and reduced residual curing effects.
Implementation Method 1
Photopolymerization AM (PAM) whereby light is used to trigger crosslinking and solidifying of polymerizable materials into complex functional 3D structures
Implementation Method 2
a light beam with a wavelength different from the photopolymerization light preferably can be applied around the cross-sectional photocuring area to inhibit the presence of reactive species outside the target boundaries
Data Source
AI summary
A system for single photon absorption based vat photopolymerization additive manufacturing with photoinhibition induced curb and photoexcitation induced cure (SPA2CurbCure), comprising: a build chamber; a two-wavelength projection irradiation unit delivering a patterned photo-curbing exposure mask and a patterned photo-curing exposure mask, respectively, to create a curing region of initiating chemicals surrounded by a distribution of inhibiting species; wherein a curing light beam comprising light having a first wavelength and a curbing light beam comprising light having a second wavelength from the irradiation unit are manipulated into adjacent complementary exposures, combined by a dichroic beam splitter and collimated into a target resin material in the build chamber.