Reacquainting Modern Engineering with the Natural World Matthew Cathell Department of Technological Studies The College of New Jersey Monday, August 10, 2009
Environmental & Biotechnology Systems Sustainable Garden Monday, August 10, 2009
Environmental & Biotechnology Systems Monday, August 10, 2009
Environmental & Biotechnology Systems Monday, August 10, 2009
Humans and Materials • throughout history, a key constraint on technological design has been availibility of materials • natural materials dominated early technology (nothing else was available!) • over time, humans developed means of obtaining and using varied and different materials • our species’ epochs are named after the materials we mastered (The Stone Age, The Bronze Age, The Iron Age) Monday, August 10, 2009
The Evolution of Materials Monday, August 10, 2009
Sustainable Development Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs. Brundtland Report World Council on Economic Development 1987 Monday, August 10, 2009
Materials & the Human-Designed World • using materials costs energy – no ways around it • some materials are more sustainable than others • drawn from a source that is renewable • must participate in a closed loop, cyclical process • “natural” does not always equal “sustainable” • very few materials used in the human-designed world today truly approach sustainability Monday, August 10, 2009
Natural v. Industrial Systems Natural Ecosystems Industrial Systems • mostly uses a few elements • uses large number of (C, N, O, H) available elements • cyclic • linear • waste reused as a resource • waste is often not reused • closed loop • open loop • is considered healthy when at • is considered healthy when in equilibrium growth Monday, August 10, 2009
Natural v. Industrial Carbon Cycle natural carbon cycle • resources are transformed naturally • balance and long-term stability industrial carbon cycle • resources are transformed by human activity • resources are not replenished at rates equaling consumption Monday, August 10, 2009
Types of Natural Materials building blocks soft tissue mineralized tissue • proteins • muscle fibers • dentine/enamel • polysaccharides • connective tissue • bone, antler • raw minerals • keratinized tissue • shell, coral wood-like materials biomaterials natural fibers • tree woods • biometals • mammalian fibers • palm, cork, bamboo • biopolymers • insect/arachnid fibers • nut shells • bioceramics • stem/leaf/seed fibers Monday, August 10, 2009
Efficiency of Biological Materials As a general principle natural selection is continually trying to economize every part of the organization Charles Darwin common characteristics of natural materials • tend to be very efficient • need to support static and dynamic loads • need to store and release elastic energy • need to flex through large angles • need to resist buckling and fracture Monday, August 10, 2009
Requirements of Biological Materials Thermal & Electrical Mechanical some materials need to: materials support loads from: • insulate • mass of the organism • conduct • fluid pressures (internal and external) • transpire • eating, fighting, moving, etc. • sense • wind and snow • actuate • attack by other organisms Unifying Principles natural biological materials tend to be: • composites • sustainable • recyclable • biodegradable Monday, August 10, 2009
Rammed Earth and Adobe • soil available almost anywhere • mix with straw or hair and some lime cement • high heat capacity • traditional building material in Mexico and parts of Africa • adobe bricks commercially available Monday, August 10, 2009
Straw and Reeds • straw bales can be stacked into wall structure and surfaced with earth plaster or wood • low thermal conductivity and low heat capacity • reeds made into thatch • reeds grow in water and have evolved resistance Monday, August 10, 2009
Hemp and Flax • fast-growing, grass-like plants • fibers have great strength • used since antiquity • “hempcrete” (mix of hemp and lime) used as infill in wood frame buildings • hempcrete is 75% hemp by volume and is truly sustainable Monday, August 10, 2009
Stone • stone is not renewable, but is certainly abundant (with certain exceptions) • durable and reliable • dressed stone is expensive, labor- and energy-intensive • fieldstone is the material as found in nature • dry stone is skilled stacking of fieldstone, and not suitable for load bearing • stone bonded with lime mortar is durable and robust Monday, August 10, 2009
The Mystery of the Pyramids Michel Barsoum, Ph.D. postulates that portions of the Pyramids are made from reconstituted limestone http://www.materials.drexel.edu/Pyramids/ Monday, August 10, 2009
Cork • cork is a protective layer found below the outer bark of many types of trees, including Quercus suber • contains the fatty acid suberin and other waxes, which make cork impervious to air, water and alcohol • can be harvested without harming tree • used as flooring surface Monday, August 10, 2009
Earthen Floors • earthen floors have high density and low thermal conductivity • radiant heating systems can be installed in the floor, which also acts as a passive solar device • sand and fiber aggregate added in controlled amounts to control cracking • sealed with linseed oil and wax • point loads not well tolerated Monday, August 10, 2009
Bamboo • bamboo is widely used as a structural material in Asian countries • material is fast-growing and quickly renewable • strength and stiffness are derived from tubular cross-sectional shape, reinforced by fiber-bundles within the cross-section • often used for oars, masts, bicycles, scaffolding and floor joists Monday, August 10, 2009
Materials Properties Databases Monday, August 10, 2009
Biomimicry Biomimicry is the design and making of human-made structures that mimic those of the natural world Monday, August 10, 2009
What Can Nature Do For Us? Monday, August 10, 2009
The Lotus Effect • the nanoscale structure of butterfly wings leads to a natural hydrophobic effect • as water droplets bead up on the wing, dust particles are swept up • by engineering a mimic of the butterfly wing surface, we can create dust-repellant surfaces Monday, August 10, 2009
Hair with hooks • the surface of a cocklebur has tiny hooks that allow adhesion to animal fur • commercial Velco mimics this natural behavior to create a reusable, non- sticky adhesion Monday, August 10, 2009
Shark Skins • sharks move through the water with high efficiency • tiny tooth-like scales on the skin direct water through groves parallel to swimming direction, reducing drag Monday, August 10, 2009
Spider Silk • spiders produce silk from an assemblage of proteins • the silk is very strong and insoluble in water • the frame structure is resistant to wind and stable in sunlight Monday, August 10, 2009
Whale Fins and Wind Turbines • whale fins have scalloped edges that help them make tight turns in the water • wind turbine blades that mimic the whale fin structure have reduced drag Monday, August 10, 2009
Newton’s Rings Monday, August 10, 2009
How Does Color Work? pigment-based color structure- based color Monday, August 10, 2009
Structural Color in Nature Monday, August 10, 2009
Structural Color in Nature Potyrailo, RA et al. Nature Photonics 2007, 1, 123. R Norris, DJ et al . Advanced Materials 2004, 16, 1393. Parker, AR et al . J. Ex. Bio. 1998, 201, 1307. Zi, H et al . Proceedings of the National Academy of Sciences of the United S.tates of America. 2003, Parker, AR et al . Nature 2003, 426, 786. 100 Monday, August 10, 2009
Mimicking the Beetle Shell no dyes or pigments spin coating polymer solution (several thousand rpm) Monday, August 10, 2009
“Shells” of Many Colors Monday, August 10, 2009
Mimicked Beetle Shell as a Sensor yellow light blue light out of in phase! phase! thin film thin film substrate substrate change refractive index change thickness in phase! in phase! thin film thin film substrate substrate Monday, August 10, 2009
Evaluating Water for Heavy Metals metal ion before after interaction • thickness • thickness • refractive • refractive • 50 ppm analyte in index index Monday, August 10, 2009
Opal • opal is a gemstone made of tiny silica particles, stacked in a regular periodic way • the silica particles are a photonic crystal, resulting in the beautiful coloration • we can mimic opal material by allowing colloidal silica particles to settle on a substrate • nature takes care of the ordered stacking! Norris, D. J. et al . Advanced Materials 2004, 16, (16), 1393-1399. Monday, August 10, 2009
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