Fabrication of cellular materials

Robert Krafft Prud'homme, Ilhan A. Aksay, Rajeev Garg

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Nature uses cellular materials in applications requiring strength while, simultaneously, minimizing raw materials requirements. Minimizing raw materials is efficient both in terms of the energy expended by the organism to synthesize the structure and in terms of the strength-to-weight ratio of the structure. Wood is the most obvious example of cellular bio-materials, and it is the focus of other presentations in this symposium. The lightweight bone structure of birds is another excellent example where weight is a key criterion. The anchoring foot of the common muscle [Mytilus edulis] whereby it attaches itself to objects is a further example of a biological system that uses a foam to fill space and yet conserve on raw materials. In the case of the muscle the foam is water filled and the foot structure distributes stress over a larger area so that the strength of the byssal thread from which it is suspended is matched to the strength of interfacial attachment of the foot to a substrate. In these examples the synthesis and fabrication of the cellular material is directed by intercellular, genetically coded, biochemical reactions. The resulting cell sizes are microns in scale. Cellular materials at the next larger scale are created by organisms at the next higher level of integration. For example an African tree frog lays her eggs in a gas/fluid foam sack she builds on a branch overhanging a pond. The outside of the foam sack hardens in the sun and prevents water evaporation. The foam structure minimizes the amount of fluid that needs to be incorporated into the sack and minimizes its weight. However, as far as the developing eggs are concerned, they are in an aqueous medium, i.e. the continuous fluid phase of the foam. After precisely six days the eggs hatch, and the solidified outer wall re-liquefies and dumps the emerging tadpoles into the pond below. The bee honeycomb is an example of a cellular material with exquisite periodicity at millimeter length scales. The cellular structure provides strength through geometric regularity and functions as both honey storage vessels and incubators.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
PublisherSociety of Photo-Optical Instrumentation Engineers
Pages331-334
Number of pages4
Volume2716
ISBN (Print)0819420913, 9780819420916
DOIs
StatePublished - Jan 1 1996
EventSmart Materials Technologies and Biomimetics - San Diego, CA, USA
Duration: Feb 26 1996Mar 2 1996

Other

OtherSmart Materials Technologies and Biomimetics
CitySan Diego, CA, USA
Period2/26/963/2/96

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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