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International Journal of Bioprinting Horsetail-inspired lattice for bone use

of multiple subsequent layers below the interface, leading numerical simulations of the RVEs and lattice matrices, as
to loss of support for the interface. The horsetail-inspired well as the conduct of physical compression testing, we can
lattice matrices, on the other hand, exhibit fragmentation derive that the three independent events can be correlated.
and the displacement of fragments, allowing compressive This correlation is instrumental in allowing future design
load transfer to unaffected portions in quick successions. process based on the modified BCC RVE to be efficient as
This characteristic potentially accounts for the higher yield initial work may be based on numerical simulations. We also
strength achieved by the horsetail-inspired lattice matrices. discovered that the isotropy characteristics are decoupled

At large strains, there is also significant fracture of struts from the outer radius of the designed lattices; this avoids
in the BCC lattice matrix at the interfacing joints, while convolution and simplifies design considerations. The
the strut members generally retain the cylindrical shape. titanium alloy-based, modified BCC lattice has an elastic
The intactness of the struts implies that energy absorption modulus range that is within the range of both cortical
may not be efficient. When compared to the horsetail- and trabecular bones. The performance can be fine-tuned
inspired lattice matrices, it can be observed that fractures through the simple modifications of preceding parameters
generate smaller fragments, as discussed, and that fractured to mitigate the differences from the elastic modulus of the
substructures are still in contact, implying the participation native bone in specific application areas, thus alleviating the
in load-bearing function. This inefficiency is apparent at effect of stress shielding. Additionally, parameters can also
larger strains above 20–30%, where the BCC lattice matrix be properly selected to achieve a non-directional lattice to
experienced low levels of stresses after lower strain levels. ease the design of the synthetic bone scaffolds. The lattice
Conversely, the horsetail-inspired lattice matrices have proposed, using the horsetail-inspired cross-section, has
consistent distributed stresses that are comparatively higher also allowed increase in surface area and voids that will
at all levels of strains. We observe that when compared to the promote cell growth and adhesion, while demonstrating
simulation of the standard BCC lattice matrix, the horsetail- good energy adsorption capabilities.
inspired matrices exhibited at least two times the specific
energy absorption, both in actual compression testing and Acknowledgments
simulation environments, as shown in Table 2. None.
While the bone tissue is not expected to be exposed
to large strains during normal conditions, the good Funding
energy absorption performance demonstrated by the This research is supported by A*STAR under its IAF PP
horsetail-inspired lattice matrices would be ideal for bone- Grant (Project No. M22K4a0044) under the work package
related applications due to the increased resilience to of “Thermal Management of Motor with Ferrofluid
accidental damage.
Composite Particles” and the MOE AcRF Tier 1Grant
4. Conclusion (Project No. A-0009123-01-00)
In our study, we proposed the use of a BCC RVE modified with Conflict of interest
the simplified horsetail-inspired cross-section on individual
strut member for use in the fabrication of synthetic bone The authors declare no conflicts of interest.
scaffolds. We demonstrated that mechanical performance of Author contributions
the modified BCC RVE can be systematically varied through
the proper control of two parameters, r and t. Through the Conceptualization: Seng Leong Adrian Tan, Miao Zhao

Table 2. Comparison of mechanical performance between finite element analysis and compression testing

Direction Derivation E matrix (GPa) Densification strain (ε ) Specific energy
absorption (kJ/kg)
d
BCC FEA 2.50 0.534 12.84
Compression Testing 11.09 ± 0.59 0.644 ± 0.037 24.58 ± 2.94
[100]
FEA 10.88 0.780 32.62
Compression Testing 11.53 ± 1.68 0.608 ± 0.042 20.79 ± 2.24
[110]
FEA 9.63 0.813 30.89
Compression Testing 9.46 ± 0.47 0.594 ± 0.009 26.05 ± 1.47
[111]
FEA 8.93 0.808 31.25
Abbreviations: BCC, body-centered cubic; FEA, finite element analysis.

Volume 10 Issue 4 (2024) 201 doi: 10.36922/ijb.2326