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. 2020 May 1;12(5):1031.
doi: 10.3390/polym12051031.

3D Direct Printing of Silicone Meniscus Implant Using a Novel Heat-Cured Extrusion-Based Printer

Eric Luis  1 , Houwen Matthew Pan  2 , Swee Leong Sing  1 , Ram Bajpai  3   4 , Juha Song  2 , Wai Yee Yeong  1
Affiliations

3D Direct Printing of Silicone Meniscus Implant Using a Novel Heat-Cured Extrusion-Based Printer

Eric Luis et al. Polymers (Basel). .

Abstract

The first successful direct 3D printing, or additive manufacturing (AM), of heat-cured silicone meniscal implants, using biocompatible and bio-implantable silicone resins is reported. Silicone implants have conventionally been manufactured by indirect silicone casting and molding methods which are expensive and time-consuming. A novel custom-made heat-curing extrusion-based silicone 3D printer which is capable of directly 3D printing medical silicone implants is introduced. The rheological study of silicone resins and the optimization of critical process parameters are described in detail. The surface and cross-sectional morphologies of the printed silicone meniscus implant were also included. A time-lapsed simulation study of the heated silicone resin within the nozzle using computational fluid dynamics (CFD) was done and the results obtained closely resembled real time 3D printing. Solidworks one-convection model simulation, when compared to the on-off model, more closely correlated with the actual probed temperature. Finally, comparative mechanical study between 3D printed and heat-molded meniscus is conducted. The novel 3D printing process opens up the opportunities for rapid 3D printing of various customizable medical silicone implants and devices for patients and fills the current gap in the additive manufacturing industry.

Keywords: 3D printing; additive manufacturing; material extrusion; meniscus implant; silicone.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Experimental setup for heat cure extrusion-based additive manufacturing (AM): legends: (1) motion control platform, (2) extruder, (3) static mixer, (4) printhead, (5) heating elements.
Figure 2
Figure 2
(a) Ecoflex30 and (b) Ecoflex50 complex viscosity and complex modulus versus shear stress.
Figure 3
Figure 3
(a) Ecoflex30 and (b) Ecoflex50 complex viscosity and shear stress versus strain rate.
Figure 4
Figure 4
(a) Eco30 and (b) Eco50 storage modulus, loss modulus, complex viscosity vs angular frequency.
Figure 5
Figure 5
Plot of curing times (s) of Ecoflex30 (orange line) and Ecoflex50 (blue line) versus temperatures (°C).
Figure 6
Figure 6
Schematic illustration of T bone: (a) overview and (b) side view. (c) Top view images of the 3D printed T bone under varied print speed. Scale bar: 1 cm.
Figure 7
Figure 7
Schematic illustration of 3D printed cylinder (a) overview and (b) side view. (c) Cross-sectional images of the cylinder. Scale bar 1 cm.
Figure 8
Figure 8
Schematic illustration of a polyhedron in (a) overview and (b) side view. (c) Top view images of the polyhedron. Scale bar: 1 cm.
Figure 9
Figure 9
Top view images of the 3D printed silicone meniscus under varied heating temperature (T1 = nozzle temperature and T2 = platform temperature) and inner nozzle diameter. Scale bar: 1 cm.
Figure 10
Figure 10
Correlation between meniscus length and (a) nozzle temperature and (b) print bed temperature.
Figure 11
Figure 11
Correlation between meniscus width and (a) nozzle temperature and (b) print bed temperature.
Figure 12
Figure 12
Bright field images of (a) surface, (b) posterior horn and (c) anterior horn of 3D printed silicone meniscus implant. (d) Scanning electron microscopy (SEM) image of meniscus surface at ×200 magnification.
Figure 13
Figure 13
(a) Temperature distribution along nozzle, (b) velocity and (c) viscosity distribution of silicone resin along nozzle.
Figure 14
Figure 14
(a) Vertical and (b) horizontal temperature distribution of the 3D printed silicone meniscus implant using one convection block simulation.
Figure 15
Figure 15
(a) Vertical and (b) horizontal temperature distribution of on-off layering simulation.
Figure 16
Figure 16
Stress vs strain plot of 3D Printed (blue line) vs heat molded silicone meniscus (red line).
See this image and copyright information in PMC

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