Research ArticleMATERIALS SCIENCE

One-step volumetric additive manufacturing of complex polymer structures

See allHide authors and affiliations

Science Advances  08 Dec 2017:
Vol. 3, no. 12, eaao5496
DOI: 10.1126/sciadv.aao5496
  • Fig. 1 Holographic volumetric 3D fabrication system schematic and example structures.

    (A) SLM, liquid crystal on silicon spatial light modulator; FTL, Fourier transform lens; BB, beam block to eliminate undiffracted light; HP, hologram plane; 4fN, telescope lens pairs in the “4-f” configuration used for beam expansion or image relaying [4f2 incorporates a pinhole spatial filter (SF)]. The inset image details the configuration of 45° prism mirrors for directing image subcomponent beams at orthogonal directions into the resin volume. (B to G) Structures fabricated using this system, each from a single exposure of 5- to 10-s duration. Scale bars, 2 mm.

  • Fig. 2 Induction time and curing dose dependence on key process parameters.

    (A) Summary of polymerization induction times ti before gelation in three-beam regions, as determined by the first appearance of cube edges, showing strut sizes from 0.6 to 1.2 mm. Error bars are estimates of data reproducibility based on N = 3 measurements at typical conditions, given one-sided due to the tendency of cure time measurements to bias upward from gradual resin degradation. Colored dotted lines are power-law fits to the data at each PI concentration. The black dashed line is the equation Embedded Image, where the variables on the right-hand side are estimated from measurements of system parameters or similar resin formulations. The insets show a typical cube structure used to generate these data, and an intensity-compensated image that was used for exposure. (B) Comparison of model-predicted and experimentally measured three-beam gel times tG3, with the dashed line indicating unit slope. Data from three different laser powers between 6 and 40 mW are represented at each PI concentration. (C) Energy doses required to cure cube struts (three-beam regions), plotted for the highest and lowest beam power used at each PI concentration.

  • Fig. 3 Optical attenuation and three-beam superposition compensation model.

    (A) Representative plane at which all three-beam contributions are calculated, shown in (B) as a heat map representing relative intensities. Beams 1 and 2 are incident from the left and bottom as indicated by black arrows, and beam 3 is directed into the page. (C and E) Summed volumetric absorption values from three-beam superposition, without compensation, at the location marked by the dashed line in (B), comparing different [PI]. (D and F) Intensity profiles at the same [PI] but compensated to attain equal peak intensity in three-beam overlap regions.

  • Fig. 4 A process performance comparison of volumetric fabrication to other polymer-based AM methods.

    Resolution is defined as 1/(2δ), where δ is the minimum feature size. The gray dashed boundary oval encloses fabrication results from two scenarios and represents the authors’ speculation regarding the near-term potential of the volumetric fabrication method reported in this work. Plotted data points represent specific published results or system operating parameters known first hand to the authors. PμSL/LAPμSL, projection micro-stereolithography and its large-area variant (8, 25, 31); CLIP (10), continuous liquid interface printing; DIW, direct ink writing (3234); DLW, direct laser writing; SLA, stereolithography; SLS, selective laser sintering. Commercial system performance is based on the manufacturer’s specifications.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/12/eaao5496/DC1

    Supplementary Materials and Methods

    fig. S1. Experimentally measured cure times for the full range of illumination intensities.

    fig. S2. Details of intensity attenuation effects and compensation for resins with differing absorption coefficients.

    fig. S3. Progression of multibeam 3D volumetric polymerization of cube structures and eventual overcuring.

    fig. S4. Representative results from the polymerization simulations.

    fig. S5. Effects of curing conditions on feature resolution and distortion.

    References (3542)

  • Supplementary Materials

    This PDF file includes:

    • Supplementary Materials and Methods
    • fig. S1. Experimentally measured cure times for the full range of illumination intensities.
    • fig. S2. Details of intensity attenuation effects and compensation for resins with differing absorption coefficients.
    • fig. S3. Progression of multibeam 3D volumetric polymerization of cube structures and eventual overcuring.
    • fig. S4. Representative results from the polymerization simulations.
    • fig. S5. Effects of curing conditions on feature resolution and distortion.
    • References (35–42)

    Download PDF

    Files in this Data Supplement:

Navigate This Article