Biomimetic Sensors and Actuators
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BIOMIMETIC SENSORS AND ACTUATORS Kelley Markowski* and Robert E. Newnharn** *Kelley Markowski The Pennsylvania State University, 135 Materials Research Laboratory. University Park, PA 16802
"**RobertE. Newnhamn The Pennsylvania State University,
251 Materials Research Laboratory.
University Park, PA 16802
ABSTRACT Several types of biornimetic structures suitable for underseas systems are described. Composite sensors and actuators are modeled after coral, fish, sharks and bats.
INTRODUCTION Imitation of the biological world as a source of ideas for innovative device designs is not a new concept. Bionimetic means to imitate life, or to use the biological world as a source of ideas for device concepts II ]. In the 1500's Leonardo Da Vinci devised schemes for flying machines based on the principle of flapping flight with a flexible wing modeled after his observations of birds. Da Vinci believed that "given the cause, nature produces the effect ini the briefest possible way" 1.2.1.Development of ideas for smart ceramics and intelligent systems, those with both sensing and actuating capabi ities, are no exception. In the "Infinite Varietie" of nature there seems to be a few basic rules to which all materials made by animals and plants must confoni to for survival, within these rules there are also some intriguing tricks nature uses which we have yet to learn to manipulate to our full advantage 13.1. The goal of this paper is to review and develop the idea of biomimetics as they relate to smart ceramics for intelligent systems. As defined here, smart materials have the ability to perfomi both sensing and actuating functions. They respond to environmental stimuli such as pressure waves, chemical concentrations, temperature changes or light pulses with mechanical motion, fluid flow, or electric current, to only mention a few of the possibilities.
BIOM.IMETICS-PAST ACCOMPLISHMENTS One of the first and most successful examples of biominetic engineering carried out in our laboratory was the mimicking of the coral structure, by a process known as repluninefoin. This biomimetic material is manufactured commercially by Interpore International and using corals imported from the South Sea Islands [4]. The uniform pore size, equal pore and solid phase volumes and pronounced three dimensional fenestrate structure are difficult to obtain artificially, although such materials are common in nature 15.1.Such a structure divides space into two interpenetrating regions each of which is a single, multiply connected phase with 3-3 connectivity
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coral-type structure. Further processing of the skeleton for transducer applications consists of backfilling the PZT with a highly flexible elastomer material, such as silicone rubber. After poling the PZT, the composite cani be crushed to yield a highly flexible transducer with low pennittivity, or maintained as a rigid solid to be used as a low-density, high-coupling resonator 11,51. For biological uses of this proces
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