Mechanical and Structural Characterization of Biological Materials Marc A. Meyers, University of California, San Diego, DMR Research Highlights: Abalone, Bone, and Antler Hierarchical structure of abalone pedal foot UntreatedDeproteinated Demineralized SEM images showing identical microstructure of untreated, deproteinated (mineral only) and demineralized (protein only) cancellous bones Abalone nacre –Hierarchical structure Mesolayers, aragonite tiles, mineral bridges –Enhanced mechanical properties compared to its building blocks Toughing mechanisms –Mineral bridges, asperities, organic glue Underwater adhesion of abalone foot –Hierarchical structure similar to gecko foot –Adhesion mechanism van der Walls & capillary interactions Mineral and protein phases in bone –Study of structure & mechanical properties of the mineral & protein phases in bone by demineralization (DM) or deproteinization (DP) Identical structural features of DM and DP bone –Strong synergistic effect - interpenetrating composite Exceptional fracture toughness of antler bone –Antler bone similar to skeletal bone but less mineralized –Highest R-curve fracture toughness of any biological material (~ 60 kJ.m 2 )

Mechanical and Structural Characterization of Biological Materials Marc A. Meyers, University of California, San Diego, DMR Beak and Feather: light weight and strength optimization Sandwich-structured composites observed in nature. Exterior rhamphotheca for beak and cortex of feather shaft are thin shells composed of overlapping tiles. Cellular structures in interior of both beak and feather. Three-dimensional closed-cell trabecular foam composed of mineralized collagen within beaks of hornbill and toucan Keratinous honeycomb structure in feathers Avian appendages exhibit signature themes of cellular solids and hierarchical structures Research Highlights: Avian Appendages Arrows indicate intermediate filaments in TEM tomograms Intermediate filaments isualized by TEM tomogram of keratin tiles of Toucan rhamphotheca. Polygonal keratin tiles measure 50 μm in approximate diameter. On the cortex of feather shaft, villous polygonal keratin tiles of similar scale Optical micrograph depicts depth of the foam structure in Toco toucan. Buckling of fibrous membranes in feather shaft medulla after tension test. Nanoscale fibers comprise microscale membranes of cells in feather medulla.

Mechanical and Structural Characterization of Biological Materials Marc A. Meyers, University of California, San Diego, DMR Undergraduates at UCSD enjoyed first-hand experience with Scanning Electron Microscopy while imaging fibrous keratin of bird feather. “Show and Tell,” for third graders at Torrey Pines Elementary learned of the design and materials Mechanics of biological materials is at the intersection of physics, engineering, biology, and chemistry. Future scientists must be prepared for the interdisciplinary approach. From the primary classroom...to high school …. to the research laboratory Shark teeth, Shells, Alligator teeth, Armadillo armor, Toucan beak, and more! High school students on UCSD summer program