Page 424 - IJB-9-6

International Journal of Bioprinting Versatile pomelo peel-inspired structures

Figure 1. (A) Longitudinal section of the pomelo. (B) Micro-CT of stochastically porous structure in pomelo peel. (C) SEM of gradient structure in pomelo
peel from endocarp to exocarp.
was used to fabricate the structure. A processing chamber 2.3. Microstructure characterization and
needs to maintain an argon atmosphere during LPBF mechanical tests
process (Figure 3B), and the oxygen content should be less The LPBF-formed structures and the substrate were
than 50 cm /m . The optimized processing parameters and separated by wire cutting and cleaned by ultrasonic
3
3
scanning strategy in our previous study (laser power of wave. These as-fabricated structures for microstructure
400 W and scanning speed of 800 mm/s) [36-38] were applied analysis were ground and polished following the classical
in this work to ensure the forming quality and forming procedures. The section was etched with a solution, HF
efficiency. It was found that the specimen processed with (2 mL) + HCl (3 mL) + HNO (5 mL) + H O (190 mL).
3
2
island strategy, among other scanning strategies, exhibited The microstructure was observed under an optical
the highest relative density (99.6%) and microhardness microscope (OM, Olympus Corporation, Japan). The
(106.3 HV ) . Therefore, the island laser scanning surface morphology of the structure was observed through
[36]
0.2
strategy with an island size of 5 × 5 mm and a scanning SEM (FEI-Quanta, USA). The 3D side surface morphology
2
direction rotation of 37° between neighboring two layers of the structure was observed and measured by laser
was used for this experiment (Figure 3C). Additionally, scanning confocal microscopy (LSCM; Mumuxili, Nanjing,
the process involved contour scanning and filling contour China). According to the ISO 13314: 2011 standard, the
scanning, with parameters (laser power of 200 W and compression tests of structures were conducted using
scanning speed of 2000 mm/s) different from the main a CM5205 testing machine (MTS Industrial System,
structural processing parameters. The as-fabricated BPPSs China) with a crosshead velocity of 1 mm/min at room
with four different VFs are shown in Figure 3D. temperature (Figure 4A). The compression direction was

Volume 9 Issue 6 (2023) 416 https://doi.org/10.36922/ijb.1011