Page 457 - IJB-9-4

International Journal of Bioprinting

RESEARCH ARTICLE
Manufacturability of functionally graded

porous β-Ti21S auxetic architected
biomaterials produced by laser powder bed

fusion: Comparison between 2D and 3D
metrological characterization

5
2
3,4
Lorena Emanuelli *, Alireza Jam , Anton du Plessis , Carlo Lora ,
1
Raffaele De Biasi , Matteo Benedetti , Massimo Pellizzari 2
2
2
1 INSTM (Operative center: University of Trento), Via Sommarive 9, Trento, Italy
2 University of Trento, Department of Industrial Engineering, Trento, Italy
3 Research Group 3D Innovation, Stellenbosch University, Stellenbosch, South Africa
4 Object Research Systems, Montreal, Canada
5 SISMA SpA, Piovene Rocchette, Vicenza, Italy
(This article belongs to the Special Issue: 3D Printing of Advanced Biomedical Devices)

Abstract

*Corresponding author: Functionally graded porous structures (FGPSs) are attracting increasing interest in the
Lorena Emanuelli manufacture of prostheses that benefit from lower stiffness and optimized pore size
(lorena.emanuelli@unitn.it)
for osseointegration. In this work, we explore the possibility of employing FGPSs with
Citation: Emanuelli L, Jam A, du auxetic unit cells. Their negative Poisson’s ratio was exploited to reduce the loss of
Plessis A, 2023, Manufacturability connection between prosthesis and bone usually occurring in standard implant loaded
of functionally graded porous
β-Ti21S auxetic architected under tension and therefore undergoing lateral shrinking. In addition, to further improve
biomaterials produced by laser osseointegration and mitigate stress shielding effects, auxetic FGPSs were fabricated in
powder bed fusion: Comparison this work using a novel β-Ti21S alloy characterized by a lower Young’s modulus compared
between 2D and 3D metrological
characterization. to traditional α + β Ti alloys. Specifically, two different auxetic FGPSs with aspect ratio
Int J Bioprint, 9(4): 728. equal to 1.5 and angle θ of 15° and 25° with a relative density (ρ ) gradient of 0.34, 0.49,
r
https://doi.org/10.18063/ijb.728 0.66 and of 0.40, 0.58, 0.75 were designed and printed by laser powder bed fusion. The 2D
Received: September 29, 2022 and 3D metrological characterization of the as-manufactured structures was compared
Accepted: November 22, 2022 with the design. 2D metrological characterization was carried out using scanning
electron microscopy analysis, while for the 3D characterization, X-ray micro-CT imaging
Published Online: April 5, 2023 was used. An undersizing of the pore size and strut thickness in the as-manufactured
Copyright: © 2023 Author(s). sample was observed in both auxetic FGPSs. A maximum difference in the strut thickness
This is an Open Access article of −14 and −22% was obtained in the auxetic structure with θ = 15° and 25°, respectively.
distributed under the terms of the
Creative Commons Attribution On the contrary, a pore undersizing of −19% and −15% was evaluated in auxetic FGPS
License, permitting distribution, with θ = 15° and 25°, respectively. Compression mechanical tests allowed to determine
and reproduction in any medium, stabilized elastic modulus of around 4 GPa for both FGPSs. Homogenization method and
provided the original work is
properly cited. analytical equation were used and the comparison with experimental data highlights a
good agreement of around 4% and 24% for θ = 15° and 25°, respectively.
Publisher’s Note: Whioce
Publishing remains neutral with
regard to jurisdictional claims in
published maps and institutional Keywords: Functionally graded porous structures; Ti-21S; Auxetic structure; Metrological
affiliations. characterization; Laser powder bed fusion; Additive manufacturing

Volume 9 Issue 4 (2023) 449 https://doi.org/10.18063/ijb.728