Smart biological systems as models for engineered structures

Certain biological structures are examined in the context of engineering structures and structural components. Among a variety of types of smartness that may be evident in biological structures, two types are of special interest to us. In the first type, there is a closed loop, and smartness can be defined as an integrated ability of structures to (a) sense one or more variables such as strain, temperature, pressure, etc., (b) process the same, and (c) act, sense and reprocess as long as permissible, to assure continued performance in accordance with design intentions. Thus there is an iterative feedback mechanism and the process is dynamic. In the second type there is an open loop, and smartness arises out of a design principle aimed at enhancing toughness, leading to mechanical integrity of the system. There is no feedback, but the microstructural design is unique. This paper discusses both these types of smartness through examples which serve as models for smart structures, but pose analytical and experimental challenges in adapting biostructural principles to engineering design.