烏賊骨板是堅固的浮力控制裝置，能使烏賊輕易地在海水中維持固定的位置。它必須能承受靜水壓力，同時重量必須夠小以獲得足夠的浮力。在本研究中，我們探討虎斑烏賊(Sepia pharaonis)骨板的結構與機械性質。骨板微結構的特徵以立體顯微鏡、X光斷層掃描技術以及電子顯微鏡觀察之。骨板具有獨特的孔隙結構，其化學成分90%以上由碳酸鈣所組成，其餘的有機物為幾丁質與蛋白質。平行而層狀堆疊的薄板之間由許多薄壁支撐，每層薄板的間距由200微米到400微米不等，立體顯微鏡的鑑定顯示出，薄板間距呈現由腹部增加到背部的趨勢。於每個腔室中，許多有機薄膜位於薄壁之間。藉由對乾燥、新鮮的試片進行三種方向的壓縮測試: 平行薄板、垂直薄板以及與薄板夾45度角的施力方向量測骨板之機械性質。結果顯示薄板展現比薄壁優越的機械性質，機械性質呈現異向性質。在不同程度變形後的試片以電子顯微鏡、X光斷層掃描技術分別觀察表面與內部結構形貌，進而探討於骨板孔隙結構的變形機制。我們亦研究構成骨板的有機物以及無機物在力學上扮演的角色，結果顯示骨板的強度由兩者的相輔相成貢獻而得。此研究成果可進一步應用於設計新型仿生複合材料或生醫領域 。

The cuttlebone is a rigid buoyancy control device which enables the cuttlefish to maintain a fixed position in water with minimal effort. It must be strong enough to withstand hydrostatic pressure and lightweight in order not to sacrifice buoyancy. In this study, structure and mechanical properties of cuttlebone obtained from Sepia pharaonis were investigated. Micro-structural features of cuttlebone were characterized by stereoscope, micro-CT, and SEM. The cuttlebone, mainly made of CaCO3 in aragonite form and chitin, had a unique cellular architecture. Parallel lamellae called septum and supporting walls named pillars formed chambers with spacing varying from 200 to 400 μm. Numerous thin organic sheets between pillars within a chamber were observed. Mechanical properties were evaluated by compression tests on dry, rehydrated and fresh samples in three loading directions – parallel, perpendicular, and 45 degree to the septums. Results showed septums exhibit superior mechanical properties orientations compared with pillars. Deformed samples were examined by micro-CT and SEM at progressive stages and deformation mechanisms were evaluated. The role of mineral and organic component of cuttlebone played in the mechanical property was evaluated by deproteinization and demineralization. The results showed strong synergistic effect between the two constituents in the strength of cuttlebone. This investigation could further lead to the design of novel bio-inspired composites and biomedical applications.

Contents
List of tables III
Figure caption IV
Chapter I Introduction 1
Chapter II Literature review 4
2.1 Biological materials 4
2.1.1 Overview 4
2.1.2 Basic building blocks 8
2.2 Cellular solids 11
2.2.1 Natural cellular solids 12
Chapter III Experimental procedure 54
3.1 Sample preparation 54
3.2 Structural characterization 54
3.2.1 Macroscopic observation 54
3.2.2 Stereoscope observation 54
3.2.3 SEM observation 55
3.3 Compression tests 55
3.3.1 The effect of the orientation of septum 56
3.3.2 The effect of hydration 57
3.3.3 The effect of strain rate 57
3.3.4 Compressive testing on deminerialized and deproteinized cuttlebone 58
3.3.5 Analysis of the stress-strain curve of compression tests 58
3.3.6 Weibull’s analysis 59
3.4 Investigation of deformation mechanism 60
3.4.1 Macroscopic observation 60
3.4.2 Microscopic observation 60
3.4.3 Synchrotron X-ray tomographic microscopy (SRXTM) 61
3.5 Liquid penetration test 61
Chapter IV Results and Discussion 72
4.1 Structural characterization 72
4.1.1 Macroscopic observation 72
4.1.2 Microscopic observation 72
4.2 Mechanical property 75
4.2.1 Anisotropic property 75
4.2.2 The effect of hydration 80
4.2.3 The effect of strain rate 82
4.2.4 Synergistic effect on mechanical property of cuttlebone 82
4.3 Liquid penetration test 84
Chapter V Conclusions 116
Chapter VI Future work 117
6.1 Hydrostatic compression test 117
6.2 Macro-scale indentation test 118
6.3 Mechanical property - the effect of pillars geometry 118
Reference 125

[1] Ashby MF, Gibson LJ, Wegst U, Olive R. The mechanical-properties of natural materials .1. material property charts. Proceedings of the Royal Society-Mathematical and Physical Sciences. 1995;450:123-40.
[2] Gibson LJ. The hierarchical structure and mechanics of plant materials. J R Soc Interface. 2012;9:2749-66.
[3] Seki Y, Schneider M, Meyers M. Structure and mechanical behavior of a toucan beak. Acta Materialia. 2005;53:5281-96.
[4] Denton EJ, Gilpinbrown JB. Buoyancy of cuttlefish, Sepia officinalis (L). Journal of the Marine Biological Association of the United Kingdom. 1961;41:319-&.
[5] Denton EJ, Gilpinbrown JB. Distribution of gas and liquid within cuttlebone. Journal of the Marine Biological Association of the United Kingdom. 1961;41:365-&.
[6] Denton EJ, Gilpinbrown JB, Howarth JV. Osmotic mechanism of cuttlebone. Journal of the Marine Biological Association of the United Kingdom. 1961;41:351-&.
[7] Denton EJ. Croonian lecture, 1973 - buoyancy and lives of modern and fossil cephalopods. Proceedings of the Royal Society Series B-Biological Sciences. 1974;185:273-+.
[8] Ward PD, Vonboletzky S. Shell implosion depth and implosion morphologies in 3 species of Sepia (cephalopoda) from the mediterranean-sea. Journal of the Marine Biological Association of the United Kingdom. 1984;64:955-66.
[9] Sherrard KM. Cuttlebone morphology limits habitat depth in eleven species of Sepia (Cephalopoda : Sepiidae). Biological Bulletin. 2000;198:404-14.
[10] Cadman J, Zhou SW, Chen YH, Li Q. Cuttlebone: Characterisation, Application and Development of Biomimetic Materials. Journal of Bionic Engineering. 2012;9:367-76.
[11] Chen PY, McKittrick J, Meyers MA. Biological materials: Functional adaptations and bioinspired designs. Progress in Materials Science. 2012;57:1492-704.
[12] Meyers MA, Chen PY, Lin AYM, Seki Y. Biological materials: Structure and mechanical properties. Progress in Materials Science. 2008;53:1-206.
[13] Gibson LJ, Ashby MF. Cellular Solids: Cambridge University Press; 1997.
[14] Bechtle S, Ang SF, Schneider GA. On the mechanical properties of hierarchically structured biological materials. Biomaterials. 2010;31:6378-85.
[15] Fratzl P. Biomimetic materials research: what can we really learn from nature's structural materials? Journal of the Royal Society Interface. 2007;4:637-42.
[16] Meyers MA, Chen PY, Lopez MI, Seki Y, Lin AYM. Biological materials: A materials science approach. Journal of the Mechanical Behavior of Biomedical Materials. 2011;4:626-57.
[17] Chen PY, Lin AY, McKittrick J, Meyers MA. Structure and mechanical properties of crab exoskeletons. Acta Biomater. 2008;4:587-96.
[18] Meyers MA, Lin AYM, Chen PY, Muyco J. Mechanical strength of abalone nacre: Role of the soft organic layer. Journal of the Mechanical Behavior of Biomedical Materials. 2008;1:76-85.
[19] Warren WE, Kraynik AM. Linear elastic behavior of a low-density Kelvin foam with open cells. Journal of Applied Mechanics-Transactions of the Asme. 1997;64:787-94.
[20] Vajjhala S, Kraynik AM, Gibson LJ. A cellular solid model for modulus reduction due to resorption of trabeculae in bone. Journal of Biomechanical Engineering-Transactions of the Asme. 2000;122:511-5.
[21] Dinwoodie JM. Timber: its nature and behaviour: Taylor & Francis; 2000.
[22] Fengel D, Stoll M. On the variation of the cell cross area, the thickness of the cell wall and of the wall layers of sprucewood tracheids within an annual ring. Holzforschung. 1973;27:1-7.
[23] Bergander A, Salmén L. Cell wall properties and their effects on the mechanical properties of fibers. Journal of materials science. 2002;37:151-6.
[24] Easterling KE, Harrysson R, Gibson LJ, Ashby MF. On the mechanics of balsa and other woods. Proceedings of the Royal Society of London Series a-Mathematical Physical and Engineering Sciences. 1982;383:31-&.
[25] Cave I. The anisotropic elasticity of the plant cell wall. Wood science and technology. 1968;2:268-78.
[26] Darwin C. The Descent of Man and Selection in Relation to Sex: Gryphon Editions; 1990.
[27] Jones J. Evolution: The point of a toucan's bill. Nature. 1985;315:182-3.
[28] Van Tyne J. The life history of the toucan Ramphastos brevicarinatus. 1929.
[29] Bühler P, Ulrich H. The visual peculiarities of the toucans’ bill and their principal biological role (Ramphastidae, Aves). Tropical biodiversity and systematics Proc of the Intern Symposium on Biodiversity and Systematics in Tropical Ecosystems1997. p. 305-10.
[30] Tattersall GJ, Andrade DV, Abe AS. Heat exchange from the toucan bill reveals a controllable vascular thermal radiator. science. 2009;325:468-70.
[31] Nesis KN. Cephalopods of the world: squids, cuttlefishes, octopuses, and allies1987.
[32] Adam W. A review of the cephalopod family Sepiidae: Trustees of the British Museum (Natural History); 1966.
[33] Jereb P, Roper CF. Cephalopods of the World. An Annotated and Illustrated Catalogue of Cephalopod Species Known to date Volume 1. Chambered nautiluses and sepioids (Nautilidae, Sepiidae, Sepiolidae, Sepiadariidae, Idiosepiidae and Spirulidae): Food and Agriculture Organization of the United Nations; 2005.
[34] Birchall JD, Thomas NL. On the architecture and function of cuttlefish bone. Journal of Materials Science. 1983;18:2081-6.
[35] Clarke FW, Wheeler WC. The inorganic constituents of marine invertebrates: U. S Gov't. Print. Off.; 1922.
[36] Nicol JAC. The biology of marine animals. 1961.
[37] Richards AG. The integument of arthropods: the chemical components and their properties, the anatomy and development, and the permeability: U of Minnesota Press; 1951.
[38] Okafor N. Isolation of chitin from the shell of the cuttlefish,< i> Sepia officinalis L. Biochimica et Biophysica Acta (BBA)-Mucoproteins and Mucopolysaccharides. 1965;101:193-200.
[39] Florek M, Fornal E, Gómez-Romero P, Zieba E, Paszkowicz W, Lekki J, et al. Complementary microstructural and chemical analyses of Sepia officinalis endoskeleton. Materials Science and Engineering: C. 2009;29:1220-6.
[40] Denton EJ, Gilpinbr.Jb. On buoyancy of pearly Nautilus. Journal of the Marine Biological Association of the United Kingdom. 1966;46:723-&.
[41] Denton EJ, Gilpinbr.Jb, Howarth JV. On buoyancy of Spirula spirula. Journal of the Marine Biological Association of the United Kingdom. 1967;47:181-&.
[42] Morse HN. osmotic pressure of aqueous solutions. 1914.
[43] Wegst U, Ashby M. The mechanical efficiency of natural materials. Philosophical Magazine. 2004;84:2167-86.
[44] Gibson LJ. Biomechanics of cellular solids. J Biomech. 2005;38:377-99.
[45] Roylance D. Stress-strain curves. Massachusetts Institute of Technology study, Cambridge. 2001.
[46] Meyers MA, Chawla KK. Mechanical behavior of materials: Cambridge University Press Cambridge; 2009.
[47] Weibull W. A statistical distribution function of wide applicability. Journal of Applied Mechanics-Transactions of the Asme. 1951;18:293-7.
[48] Giraud-Guille M-M. Plywood structures in nature. Current Opinion in Solid State and Materials Science. 1998;3:221-7.
[49] Raabe D, Sachs C, Romano P. The crustacean exoskeleton as an example of a structurally and mechanically graded biological nanocomposite material. Acta Materialia. 2005;53:4281-92.
[50] Bai WB, Lin YC, Hou TK, Hong TM. Scaling relation for a compact crumpled thin sheet. Physical Review E. 2010;82.