Biomimetic Anisotropic Reinforcement Architectures by Electrically Assisted Nanocomposite 3D Printing

Abstract

Biomimetic architectures with Bouligand-type carbon nanotubes are fabricated by an electrically assisted 3D-printing method. The enhanced impact resistance is attributed to the energy dissipation by the rotating anisotropic layers. This approach is used to mimic the collagen-fiber alignment in the human meniscus to create a reinforced artificial meniscus with circumferentially and radially aligned carbon nanotubes.

Keywords: anisotropic properties; artificial meniscus; biomimetics; electrically assisted 3D printing; high impact resistance.

Figure 1

Biomimetic architectures with Bouligand-type MWCNT-S can be recreated by electrically assisted 3D printing. a) The diagram of Homarus americanus and the microstructure of claws made with Bouligand-type Chitin-protein fibers ; b) Schematic diagram of different alignment of carbon nanotubes by the rotation of the electrodes; c) Surface optical microscopy images and SEM images of fracture surface for different alignment of MWCNT-S corresponding to b; d) Schematic diagram of layer by layer bioinspired Bouligand-type MWCNT-S fabricated by the electrically assisted nanocomposite 3D printing.

Figure 2

Schematic diagram of the electrically assisted 3D printing platform for the creation of reinforcement anisotropic composites. a) Diagram of electrically assisted 3D printing device, the rotation of electrodes is controlled by the platform; b) A bottom-up projection process; c) Two parallel electrodes with applied DC electric field and the electrical potential simulated by Comsol Multiphysics; d) Schematic diagram shows rotation of CNT in polymer resin under the application of electric field.

Figure 3

Schematic diagram of the printing process of functional models by electrically assisted 3D printing. a) the Menger sponge model by solid works, b) sliced in our digital micro-mirror device based Stereolithography (DMD-based SL) software to generate different patterns for projection as shown in c) and f); d) The diagram of the electrically assisted 3D printer; e) Photo of the fabricated Menger model; g) The optical microscopy images of different portions in e) on the model different colors of triangles are marked with magnified SEM images to show the details.

Figure 4

Impact resistance test for Menger models with different rotation angles. a) Diagram of the rotation for different layers; b) unit cell repetition along z-axis for N=4; c) Schematic diagram of different types of layered pitch; d) micrograph of the fraction of electrically assisted 3D printed models by the same compression load (30N); e) Comparison of load of fracture for the models printed by pure resin, random MWCNT-S and aligned MWCNT-S with different N values; (f) Schematic diagram showing the direction of crack propagation (red lines) and crack arrest (yellow lines) for different rotation angles in the printed structure; g) Simulations by Comsol Multiphysics show the stress distribution for different values of N under the same compression (200 k Pa)-arrows show the direction of the force.

Figure 5

The schematic diagram of artificial meniscus fabricated by electrically assisted 3D printing. a) model of medial meniscus by Solidworks; b) Model was sliced in the DMD-based SL software to generate different types of patterns for different layers (c); d) Printed medial meniscus; e) Optical microscopy images show radial and circumferential alignment MWCNT-S for one layer and interconnecting for adjacent two layers; f) Schematic diagram of aligned fibers in Human meniscus and the bio-mimic, dog-bone bars for tensile test cut from different parts in the medial meniscus, g) Comparison of tensile modulus in different parts of printed meniscus made by using the pure resin B, PB/random MWCNT-S and PB/aligned MWCNT-S, Simulation by Comsol Multiphysics to show tears in human meniscus, vertical tear (h) and radial tear (j) of human meniscus under circumferential tensile loads and radial shear forces, the relative strain of the printed meniscus with the reinforcement of aligned MWCNT-S under the same forces (i and k).