Skip to main content
SpringerLink
Log in

Experimental and numerical characterization of 3D-printed scaffolds under monotonic compression with the aid of micro-CT volume reconstruction

  • Research Article
  • Published:
Bio-Design and Manufacturing Aims and scope Submit manuscript

Abstract

Even when damaged by injury or disease bone tissue has the remarkable ability to regenerate. When this process is limited by large size bone defects, tissue engineering is responsible for restoring, maintaining or improving tissue function. Scaffolds are support structures, designed to be implanted in the damaged site, supporting mechanical loads and protecting the regenerating bone tissue. In this paper, 3D-printed PLA scaffolds with three different porosity values and two different geometries were experimentally and numerically characterized. Micro-CT analysis showed that fused filament fabrication can be used to produce scaffolds with the desired porosity and 100% of interconnected pores. Under monotonical compression, scaffolds apparent compressive modulus increased from 89 to 918 MPa, while yield stress increased from 2.9 to 27.5 MPa as porosity decreased from 70 to 30%. Open porosity decreased up to 8% on aligned scaffolds and 14% on staggered scaffolds, after compression, while scaffold’s surface-to-volume ratio highest reduction (7.48 to 4.55 mm−1) was obtained with aligned low porosity scaffolds. Micro-CT volume reconstruction allowed for scaffold simplified numerical models to be built and analyzed. Excellent agreement was found when predicting scaffold’s apparent compressive modulus. Overall, it can be concluded that 3D printing is a viable scaffold manufacturing technique for trabecular bone replacement.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10
Fig. 11
Fig. 12
Fig. 13
Fig. 14
Fig. 15
Fig. 16
Fig. 17

Similar content being viewed by others

References

  1. Gregor A, Filová E, Novák M et al (2017) Designing of PLA scaffolds for bone tissue replacement fabricated by ordinary commercial 3D printer. J Biol Eng 11:1–21. https://doi.org/10.1186/s13036-017-0074-3

    Article  Google Scholar 

  2. Roseti L, Parisi V, Petretta M et al (2017) Scaffolds for bone tissue engineering: state of the art and new perspectives. Mater Sci Eng C 78:1246–1262. https://doi.org/10.1016/j.msec.2017.05.017

    Article  Google Scholar 

  3. Sin D, Miao X, Liu G et al (2010) Polyurethane (PU) scaffolds prepared by solvent casting/particulate leaching (SCPL) combined with centrifugation. Mater Sci Eng C 30:78–85. https://doi.org/10.1016/j.msec.2009.09.002

    Article  Google Scholar 

  4. Thadavirul N, Pavasant P, Supaphol P (2014) Development of polycaprolactone porous scaffolds by combining solvent casting, particulate leaching, and polymer leaching techniques for bone tissue engineering. J Biomed Mater Res Part A 102:3379–3392. https://doi.org/10.1002/jbm.a.35010

    Article  Google Scholar 

  5. Intranuovo F, Gristina R, Brun F et al (2014) Plasma modification of PCL porous scaffolds fabricated by solvent-casting/particulate-leaching for tissue engineering. Plasma Process Polym 11:184–195. https://doi.org/10.1002/ppap.201300149

    Article  Google Scholar 

  6. Tuzlakoglu K, Bolgen N, Salgado AJ et al (2005) Nano- and micro-fiber combined scaffolds: a new architecture for bone tissue engineering. J Mater Sci Mater Med 16:1099–1104. https://doi.org/10.1007/s10856-005-4713-8

    Article  Google Scholar 

  7. Thomson RC, Wake MC, Yaszemski MJ, Mikos AG (1995) Biodegradable polymer scaffolds to regenerate organs. Adv Polym Sci 122:245–274

    Article  Google Scholar 

  8. Trachtenberg JE, Mountziaris PM, Miller JS et al (2014) Open-source three-dimensional printing of biodegradable polymer scaffolds for tissue engineering. J Biomed Mater Res Part A 102:4326–4335. https://doi.org/10.1002/jbm.a.35108

    Article  Google Scholar 

  9. Nam YS, Park TG (1999) Porous biodegradable polymeric scaffolds prepared by thermally induced phase separation. J Biomed Mater Res 47:8–17. https://doi.org/10.1002/(SICI)1097-4636(199910)47:1%3c8::AID-JBM2%3e3.0.CO;2-L

    Article  Google Scholar 

  10. Do KH, Bae EH, Kwon IC et al (2004) Effect of PEG–PLLA diblock copolymer on macroporous PLLA scaffolds by thermally induced phase separation. Biomaterials 25:2319–2329. https://doi.org/10.1016/j.biomaterials.2003.09.011

    Article  Google Scholar 

  11. Rowlands AS, Lim SA, Martin D, Cooper-White JJ (2007) Polyurethane/poly(lactic-co-glycolic) acid composite scaffolds fabricated by thermally induced phase separation. Biomaterials 28:2109–2121. https://doi.org/10.1016/j.biomaterials.2006.12.032

    Article  Google Scholar 

  12. Malmström J, Adolfsson E, Emanuelsson L, Thomsen P (2008) Bone ingrowth in zirconia and hydroxyapatite scaffolds with identical macroporosity. J Mater Sci Mater Med 19:2983–2992. https://doi.org/10.1007/s10856-007-3045-2

    Article  Google Scholar 

  13. Ravi P, Shiakolas PS, Welch TR (2017) Poly-l-lactic acid: pellets to fiber to fused filament fabricated scaffolds, and scaffold weight loss study. Addit Manuf 16:167–176. https://doi.org/10.1016/j.addma.2017.06.002

    Article  Google Scholar 

  14. Germain L, Fuentes CA, van Vuure AW et al (2018) 3D-printed biodegradable gyroid scaffolds for tissue engineering applications. Mater Des 151:113–122. https://doi.org/10.1016/j.matdes.2018.04.037

    Article  Google Scholar 

  15. Korpela J, Kokkari A, Korhonen H et al (2013) Biodegradable and bioactive porous scaffold structures prepared using fused deposition modeling. J Biomed Mater Res Part B Appl Biomater 101B:610–619. https://doi.org/10.1002/jbm.b.32863

    Article  Google Scholar 

  16. Gleadall A, Visscher D, Yang J et al (2018) Review of additive manufactured tissue engineering scaffolds: relationship between geometry and performance. Burn Trauma 6:19. https://doi.org/10.1186/s41038-018-0121-4

    Article  Google Scholar 

  17. Zhang L, Yang G, Johnson BN, Jia X (2019) Three-dimensional (3D) printed scaffold and material selection for bone repair. Acta Biomater 84:16–33. https://doi.org/10.1016/j.actbio.2018.11.039

    Article  Google Scholar 

  18. Cavo M, Scaglione S (2016) Scaffold microstructure effects on functional and mechanical performance: integration of theoretical and experimental approaches for bone tissue engineering applications. Mater Sci Eng C 68:872–879. https://doi.org/10.1016/j.msec.2016.07.041

    Article  Google Scholar 

  19. Hollister S, Lin C, Saito E et al (2005) Engineering craniofacial scaffolds. Orthod Craniofacial Res 8:162–173. https://doi.org/10.1111/j.1601-6343.2005.00329.x

    Article  Google Scholar 

  20. Karageorgiou V, Kaplan D (2005) Porosity of 3D biomaterial scaffolds and osteogenesis. Biomaterials 26:5474–5491. https://doi.org/10.1016/j.biomaterials.2005.02.002

    Article  Google Scholar 

  21. Moroni L, Poort G, Van Keulen F et al (2006) Dynamic mechanical properties of 3D fiber-deposited PEOT/PBT scaffolds: an experimental and numerical analysis. J Biomed Mater Res Part A 78A:605–614. https://doi.org/10.1002/jbm.a.30716

    Article  Google Scholar 

  22. Wieding J, Wolf A, Bader R (2014) Numerical optimization of open-porous bone scaffold structures to match the elastic properties of human cortical bone. J Mech Behav Biomed Mater 37:56–68. https://doi.org/10.1016/j.jmbbm.2014.05.002

    Article  Google Scholar 

  23. Baptista R, Guedes M, Pereira MFC et al (2020) On the effect of design and fabrication parameters on mechanical performance of 3D printed PLA scaffolds. Bioprinting 20:e00096. https://doi.org/10.1016/j.bprint.2020.e00096

    Article  Google Scholar 

  24. Baptista R, Guedes M (2020) Design and printing parameters effect on PLA fused filament fabrication scaffolds. In: Almeida H, Vasco J (eds) Progress in digital and physical manufacturing. Springer, Cham, pp 131–136

    Chapter  Google Scholar 

  25. Jia S, Yu D, Zhu Y et al (2017) Morphology, crystallization and thermal behaviors of PLA-based composites: wonderful effects of hybrid GO/PEG via dynamic impregnating. Polymers (Basel) 9:528–547

    Article  Google Scholar 

  26. Müller AJ, Ávila M, Saenz G, Salazar J (2015) Crystallization of PLA-based Materials. In: Jiménez A, Peltzer M, Ruseckaite R (eds) Poly(lactic acid) science and technology: processing, properties, additives and applications. The Royal Society of Chemistry, London, pp 66–98

    Google Scholar 

  27. Gregorova A (2013) Application of differential scanning calorimetry to the characterization of biopolymers. In: Elkordy AA (ed) Applications of calorimetry in a wide context—differential scanning calorimetry, isothermal titration calorimetry and microcalorimetry. InTech, Rijeka, pp 1–20

    Google Scholar 

  28. Fischer EW, Sterzel HJ, Wegner G (1973) Investigation of the structure of solution grown crystals of lactide copolymers by means of chemical reactions. Kolloid-Z und Zeitschrift für Polym 251:980–990. https://doi.org/10.1007/BF01498927

    Article  Google Scholar 

  29. Domingos M, Chiellini F, Gloria A et al (2012) Effect of process parameters on the morphological and mechanical properties of 3D bioextruded poly(ε-caprolactone) scaffolds. Rapid Prototyp J 18:56–67. https://doi.org/10.1108/13552541211193502

    Article  Google Scholar 

  30. Liu H, Ahlinder A, Yassin MA et al (2020) Computational and experimental characterization of 3D-printed PCL structures toward the design of soft biological tissue scaffolds. Mater Des 188:108488. https://doi.org/10.1016/j.matdes.2020.108488

    Article  Google Scholar 

  31. Vikingsson L, Gómez-Tejedor JA, Gallego Ferrer G, Gómez Ribelles JL (2015) An experimental fatigue study of a porous scaffold for the regeneration of articular cartilage. J Biomech 48:1310–1317. https://doi.org/10.1016/j.jbiomech.2015.02.013

    Article  Google Scholar 

  32. Esposito Corcione C, Gervaso F, Scalera F et al (2019) Highly loaded hydroxyapatite microsphere/PLA porous scaffolds obtained by fused deposition modelling. Ceram Int 45:2803–2810. https://doi.org/10.1016/j.ceramint.2018.07.297

    Article  Google Scholar 

  33. Serra T, Ortiz-Hernandez M, Engel E et al (2014) Relevance of PEG in PLA-based blends for tissue engineering 3D-printed scaffolds. Mater Sci Eng C 38:55–62. https://doi.org/10.1016/j.msec.2014.01.003

    Article  Google Scholar 

  34. Hoque ME, Hutmacher DW, Feng W et al (2005) Fabrication using a rapid prototyping system and in vitro characterization of PEG-PCL-PLA scaffolds for tissue engineering. J Biomater Sci Polym Ed 16:1595–1610. https://doi.org/10.1163/156856205774576709

    Article  Google Scholar 

  35. Todo M, Kuraoka H, Kim J et al (2008) Deformation behavior and mechanism of porous PLLA under compression. J Mater Sci 43:5644–5646

    Article  Google Scholar 

  36. Baptista R, Guedes M (2021) Morphological and mechanical characterization of 3D printed PLA scaffolds with controlled porosity for trabecular bone tissue replacement. Mater Sci Eng C 118:111528. https://doi.org/10.1016/j.msec.2020.111528

    Article  Google Scholar 

  37. Burg K (2014) Poly(α-ester)s. In: Natural and synthetic biomedical polymers. Elsevier, pp 115–121

  38. Kister G, Cassanas G, Vert M (1998) Effects of morphology, conformation and configuration on the IR and Raman spectra of various poly(lactic acid)s. Polymer (Guildf) 39:267–273. https://doi.org/10.1016/S0032-3861(97)00229-2

    Article  Google Scholar 

  39. Ross G, Ross S, Tighe BJ (2017) Bioplastics: new routes, new products. In: Brydson’s plastics materials. Butterworth-Heinemann, pp 631–652

  40. Valainis D, Dondl P, Foehr P et al (2019) Integrated additive design and manufacturing approach for the bioengineering of bone scaffolds for favorable mechanical and biological properties. Biomed Mater 14:065002. https://doi.org/10.1088/1748-605X/ab38c6

    Article  Google Scholar 

  41. Senatov FS, Niaza KV, Stepashkin AA, Kaloshkin SD (2016) Low-cycle fatigue behavior of 3d-printed PLA-based porous scaffolds. Compos Part B Eng 97:193–200. https://doi.org/10.1016/j.compositesb.2016.04.067

    Article  Google Scholar 

  42. Gleadall A, Ashcroft I, Segal J (2018) VOLCO: a predictive model for 3D printed microarchitecture. Addit Manuf 21:605–618. https://doi.org/10.1016/j.addma.2018.04.004

    Article  Google Scholar 

  43. Marei NH, El-Sherbiny IM, Lotfy A et al (2016) Mesenchymal stem cells growth and proliferation enhancement using PLA vs PCL based nanofibrous scaffolds. Int J Biol Macromol 93:9–19. https://doi.org/10.1016/j.ijbiomac.2016.08.053

    Article  Google Scholar 

  44. Derakhshanfar S, Mbeleck R, Xu K et al (2018) 3D bioprinting for biomedical devices and tissue engineering: a review of recent trends and advances. Bioact Mater 3:144–156. https://doi.org/10.1016/j.bioactmat.2017.11.008

    Article  Google Scholar 

  45. Zein I, Hutmacher DW, Tan KC, Teoh SH (2002) Fused deposition modeling of novel scaffold architectures for tissue engineering applications. Biomaterials 23:1169–1185. https://doi.org/10.1016/S0142-9612(01)00232-0

    Article  Google Scholar 

  46. Serra T, Planell JA, Navarro M (2013) High-resolution PLA-based composite scaffolds via 3-D printing technology. Acta Biomater 9:5521–5530. https://doi.org/10.1016/j.actbio.2012.10.041

    Article  Google Scholar 

  47. Grémare A, Guduric V, Bareille R et al (2018) Characterization of printed PLA scaffolds for bone tissue engineering. J Biomed Mater Res Part A 106:887–894. https://doi.org/10.1002/jbm.a.36289

    Article  Google Scholar 

  48. Choi WJ, Hwang KS, Kwon HJ et al (2020) Rapid development of dual porous poly(lactic acid) foam using fused deposition modeling (FDM) 3D printing for medical scaffold application. Mater Sci Eng C 110:110693. https://doi.org/10.1016/j.msec.2020.110693

    Article  Google Scholar 

  49. Yan Y, Chen H, Zhang H et al (2019) Vascularized 3D printed scaffolds for promoting bone regeneration. Biomaterials 190–191:97–110. https://doi.org/10.1016/j.biomaterials.2018.10.033

    Article  Google Scholar 

  50. Moroni L, De Wijn JR, Van Blitterswijk CA (2006) 3D fiber-deposited scaffolds for tissue engineering: influence of pores geometry and architecture on dynamic mechanical properties. Biomaterials 27:974–985. https://doi.org/10.1016/j.biomaterials.2005.07.023

    Article  Google Scholar 

  51. Park S, Kim G, Jeon YC et al (2009) 3D polycaprolactone scaffolds with controlled pore structure using a rapid prototyping system. J Mater Sci Mater Med 20:229–234. https://doi.org/10.1007/s10856-008-3573-4

    Article  Google Scholar 

  52. Rodrigues N, Benning M, Ferreira AM et al (2016) Manufacture and characterisation of porous PLA scaffolds. In: Procedia CIRP. pp 33–38

  53. Rosenzweig DH, Carelli E, Steffen T et al (2015) 3D-printed ABS and PLA scaffolds for cartilage and nucleus pulposustissue regeneration. Int J Mol Sci 16:15118–15135. https://doi.org/10.3390/ijms160715118

    Article  Google Scholar 

  54. Szojka A, Lalh K, Andrews SHJ et al (2017) Biomimetic 3D printed scaffolds for meniscus tissue engineering. Bioprinting 8:1–7. https://doi.org/10.1016/j.bprint.2017.08.001

    Article  Google Scholar 

  55. Wu D, Isaksson P, Ferguson SJ, Persson C (2018) Young’s modulus of trabecular bone at the tissue level: a review. Acta Biomater 78:1–12. https://doi.org/10.1016/j.actbio.2018.08.001

    Article  Google Scholar 

  56. Li S, Zahedi A, Silberschmidt V (2018) Numerical simulation of bone cutting. In: Numerical methods and advanced simulation in biomechanics and biological processes. Elsevier, pp 187–201

  57. Kopperdahl DL, Keaveny TM (1998) Yield strain behavior of trabecular bone. J Biomech 31:601–608. https://doi.org/10.1016/S0021-9290(98)00057-8

    Article  Google Scholar 

  58. Fatihhi SJ, Rabiatul AAR, Harun MN et al (2016) Effect of torsional loading on compressive fatigue behaviour of trabecular bone. J Mech Behav Biomed Mater 54:21–32. https://doi.org/10.1016/j.jmbbm.2015.09.006

    Article  Google Scholar 

  59. Taylor D (2000) Scaling effects in the fatigue strength of bones from different animals. J Theor Biol 206:299–306. https://doi.org/10.1006/jtbi.2000.2125

    Article  Google Scholar 

  60. Skalka P, Slámečka K, Montufar EB, Čelko L (2019) Estimation of the effective elastic constants of bone scaffolds fabricated by direct ink writing. J Eur Ceram Soc 39:1586–1594. https://doi.org/10.1016/j.jeurceramsoc.2018.12.024

    Article  Google Scholar 

  61. Provaggi E, Capelli C, Rahmani B et al (2019) 3D printing assisted finite element analysis for optimising the manufacturing parameters of a lumbar fusion cage. Mater Des 163:107540. https://doi.org/10.1016/j.matdes.2018.107540

    Article  Google Scholar 

  62. Koc B, Acar AA, Weightman A et al (2019) Biomanufacturing of customized modular scaffolds for critical bone defects. CIRP Ann 68:209–212. https://doi.org/10.1016/j.cirp.2019.04.106

    Article  Google Scholar 

  63. Fostad G, Hafell B, Førde A et al (2009) Loadable TiO2 scaffolds—a correlation study between processing parameters, micro CT analysis and mechanical strength. J Eur Ceram Soc 29:2773–2781. https://doi.org/10.1016/j.jeurceramsoc.2009.03.017

    Article  Google Scholar 

  64. Liu F, Mao Z, Zhang P et al (2018) Functionally graded porous scaffolds in multiple patterns: new design method, physical and mechanical properties. Mater Des 160:849–860. https://doi.org/10.1016/j.matdes.2018.09.053

    Article  Google Scholar 

  65. Egan PF, Gonella VC, Engensperger M et al (2017) Computationally designed lattices with tuned properties for tissue engineering using 3D printing. PLoS ONE 12:1–20. https://doi.org/10.1371/journal.pone.0182902

    Article  Google Scholar 

  66. Lipowiecki M, Ryvolová M, Töttösi Á et al (2014) Permeability of rapid prototyped artificial bone scaffold structures. J Biomed Mater Res Part A 102:4127–4135. https://doi.org/10.1002/jbm.a.35084

    Article  Google Scholar 

  67. Bergström JS, Hayman D (2016) An overview of mechanical properties and material modeling of polylactide (PLA) for medical applications. Ann Biomed Eng 44:330–340. https://doi.org/10.1007/s10439-015-1455-8

    Article  Google Scholar 

  68. Eshraghi S, Das S (2012) Micromechanical finite-element modeling and experimental characterization of the compressive mechanical properties of polycaprolactone–hydroxyapatite composite scaffolds prepared by selective laser sintering for bone tissue engineering. Acta Biomater 8:3138–3143. https://doi.org/10.1016/j.actbio.2012.04.022

    Article  Google Scholar 

  69. Andreassen E, Andreasen CS (2014) How to determine composite material properties using numerical homogenization. Comput Mater Sci 83:488–495. https://doi.org/10.1016/j.commatsci.2013.09.006

    Article  Google Scholar 

  70. Duan S, Xi L, Wen W, Fang D (2020) Mechanical performance of topology-optimized 3D lattice materials manufactured via selective laser sintering. Compos Struct 238:111985. https://doi.org/10.1016/j.compstruct.2020.111985

    Article  Google Scholar 

  71. Dutra TA, Ferreira RTL, Resende HB et al (2020) A complete implementation methodology for asymptotic homogenization using a finite element commercial software: preprocessing and postprocessing. Compos Struct 245:112305. https://doi.org/10.1016/j.compstruct.2020.112305

    Article  Google Scholar 

Download references

Acknowledgements

This work was supported by FCT, through IDMEC under LAETA (project UIDB/50022/2020), CeFEMA (UID/CTM/04540/2019) and CERENA (UIDB/04028/2020). IPFN activities also received financial support from FCT through Projects UIDB/50010/2020 and UIDP/50010/2020.

Author information

Authors and Affiliations

  1. CDP2T, Departamento de Engenharia Mecânica, Escola Superior de Tecnologia de Setúbal, Instituto Politécnico de Setúbal, 2910-761, Setúbal, Portugal

    R. Baptista & M. Guedes

  2. CERENA, DECivil, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001, Lisbon, Portugal

    M. F. C. Pereira & A. Maurício

  3. IDMEC, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001, Lisbon, Portugal

    R. Baptista, D. Rechena & V. Infante

  4. IPFN, Instituto Superior Técnico, Universidade de Lisboa, 1049-001, Lisbon, Portugal

    D. Rechena

  5. CeFEMA, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001, Lisbon, Portugal

    M. Guedes

Authors
  1. R. Baptista
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. M. F. C. Pereira
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. A. Maurício
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. D. Rechena
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. V. Infante
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. M. Guedes
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

RB, MP, AM, and DR were involved in conceptualization. RB, MP, DR, VI, and MG were involved in methodology. RB, DR, and MG were involved in formal analysis and writing—original draft. RB, MP, AM, DR, VI, and MG were involved in investigation and resources. RB and DR were involved in software. RB and AM were involved in visualization. RB was responsible for supervision. AM was involved in data curation. MP, VI and MG were involved in writing—review and editing. VI and MG were involved in validation.

Corresponding author

Correspondence to R. Baptista.

Ethics declarations

Conflict of interest

The authors declare that there is no conflict of interest.

Ethical approval

This study does not contain any studies with human or animal subjects performed by any of the authors.

Supplementary Information

Below is the link to the Supplementary Information.

Supplementary Information 1 (DOCX 1605 kb)

Supplementary Information 2 (MP4 12377 kb)

Supplementary Information 3 (MP4 18021 kb)

Supplementary Information 4 (MP4 18476 kb)

Supplementary Information 5 (MP4 10524 kb)

Supplementary Information 6 (MP4 18818 kb)

Supplementary Information 7 (MP4 17821 kb)

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Baptista, R., Pereira, M.F.C., Maurício, A. et al. Experimental and numerical characterization of 3D-printed scaffolds under monotonic compression with the aid of micro-CT volume reconstruction. Bio-des. Manuf. 4, 222–242 (2021). https://doi.org/10.1007/s42242-020-00122-3

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s42242-020-00122-3

Keywords

Search

Navigation