Research ArticleAPPLIED SCIENCES AND ENGINEERING

Hydrogel 3D printing with the capacitor edge effect

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Science Advances  22 Mar 2019:
Vol. 5, no. 3, eaau8769
DOI: 10.1126/sciadv.aau8769
  • Fig. 1 Principle of PLEEC.

    An asymmetric capacitor is separated by a dielectric layer.

  • Fig. 2 Demonstrations of PLEEC.

    (A) Asymmetric capacitors with different shapes. The lower electrodes have double the widths of the upper electrodes. When the voltage is on, the liquid is trapped within the patterned region of the lower electrodes. (B) Liquid pattern in the shape of an angry bird. (C) Liquid pattern of four letters “X,” “J,” “T,” and “U.” (D) Liquid patterns of nine natural numbers by independently controlling line pixels. (E) Changeable liquid patterns in the same PLEEC panel by independently controlling 10 × 10 pixels. (F) Liquid patterns of four representative hydrogel precursors with different chemical and physical properties and polymerization into hydrogel by different polymerization methods. (G) Liquid patterns of four functional materials: temperature sensitive, biocompatible, ionically conductive, and molding materials. Photo credit: Jikun Wang, Xi’an Jiaotong University.

  • Fig. 3 Hydrogel 3D printing process with PLEEC.

    (A and B) Patterning process. When liquids flow over the designed electrode, the liquid patterns are trapped by the electric field. (C) Polymerization process. The curing platform moves down to contact the liquid pattern, and the hydrogel solution is polymerized by UV light. (D) Resetting process. The curing platform moves upward together with the newly formed hydrogel layer.

  • Fig. 4 Hydrogel 3D printing system with PLEEC.

    (A) System schematic. The system consists of seven parts: a mechanical module, a PLEEC panel, a solution-adding unit, a curing platform, a curing unit, a power supply, and a control module. (B) Our in-house printing system. Photo credit: Jikun Wang, Xi’an Jiaotong University.

  • Fig. 5 Printed hydrogel structures using the PLEEC system.

    (A) Scaffold-structured hydrogel lattice. (B and C) PAAm and PNIPAM hydrogel composites. When the polymerized hydrogel composite is placed in hot water, the PNIPAM hydrogel tends to shrink so that fingers roll up. (D) Stretchable LED belt. LEDs work well when the belt is stretched to double its length and suffers 100 loading cycles. (E) Soft display device. Each LED can be lit independently. Photo credit: Jikun Wang, Xi’an Jiaotong University.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/3/eaau8769/DC1

    Fig. S1. Distributions of electric fields simulated using COMSOL.

    Fig. S2. Calculation of the free energy for the system.

    Fig. S3. Characteristic size of the PLEEC panel.

    Fig. S4. Working process of the solution-adding unit.

  • Supplementary Materials

    This PDF file includes:

    • Fig. S1. Distributions of electric fields simulated using COMSOL.
    • Fig. S2. Calculation of the free energy for the system.
    • Fig. S3. Characteristic size of the PLEEC panel.
    • Fig. S4. Working process of the solution-adding unit.

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