National Science Foundation Inspirations from Nature Joanna M. McKittrick, University of California-San Diego, DMR Flexible armor of seahorses The seahorse tail is composed of a dermal, bony plated armor arranged in articulating ring-like segments that interlock to facilitate ventral bending and twisting. When compressed, the bony plates slide past one another, allowing the tail to deform up to ~50% without fracturing the central vertebral column. This configuration is used to build a robotic seahorse tail for flexible gripping applications. Fig. 1. Seahorse armor protecting the tail against fracture when crushed Mineral only Organic only Rigid carapace of the boxfish Boxfish have an unusual rigid carapace that provides protection against predators at a high cost of mobility. The design of the carapace and horn (Fig. 2) leads to high energy absorption under loading, providing inspiration for the design of protective shells. 5 mm 10 mm Fig. 2. Structure of the boxfish horn. Fig. 3. Structure of (a) mineral and (b) organic constituents in the abalone shell Isolated constituents in the abalone shell Shell sections were treated to remove all organic (Fig. 3a) or remove all mineral (Fig. 3b) to isolate the individual constituents. The strength measurements confirm the importance of the integrated structure. This insight can guide the design of composite laminates.

National Science Foundation From Inspiration to Applications Joanna M. McKittrick, University of California-San Diego, DMR Fig. 1. TiO 2 scaffolds freeze cast with varying slurry properties: (A) pH 7, (B) pH 7, (C) pH 7 with 5 vol.% isopropanol alcohol. All images are 250 µm wide. Bioinspired scaffolds with varying pore architectures Freeze casting is a convenient method to fabricate porous ceramic scaffolds with a variety of microstructural architectures (Fig. 1a,b,c). The scaffolds duplicate the mineral arrangement in seashells and bone. By altering the chemical composition of the initial ceramic slurry, the freezing properties of the slurry may be changed to control the resulting pore morphology of the scaffolds. ABC Spiraling ceramics with enhanced torsional rigidity Magnetic field aligned freeze casting, inspired by the narwhal tusk, was invented that allows for the microstructures of porous ceramics to be aligned in multiple directions. Spiraling ceramic-polymer composites with enhanced torsional rigidity were fabricated by freeze casting under an applied rotating magnetic field followed by subsequent polymer infiltration (Fig. 2A,B,C). The angle and direction of spiral reinforcement can be tailored to exhibit a maximum torsional strength or stiffness, without altering the material composition (Fig. 2D). Fig. 2. ZrO 2 -Epoxy composites freeze cast under a 0.12 T magnetic field rotated about the freezing direction: (A) 0.05 rpm, (B) 0.20 rpm, (C) 0.40 rpm. All composites are ~7mm in diameter. (D) Representative shear stress- strain plot comparing the composites with different angles of spiral reinforcement. D

National Science Foundation Education and Outreach Joanna M. McKittrick, University of California-San Diego, DMR Undergraduate students Zherrina Manilay and Vanessa Nguyen presented their research at UCSD Summer Undergraduate Research Conference Undergraduate student Matthew Wen explaining the principles of freeze casting to the members of Society of Women Engineers Graduate student Michael Porter at the Science Discovery Day at Torrey Pines Elementary school Dr. Ekaterina Novitskaya explains the beauty of biological materials to the students from Society of Women Engineers High school student Koziah Ferebee holds abalone at Scripps Institute of Oceanography Dr. Wen Yang and high school students performed tensile testing on fish scales.