02-06-2015, 04:09 PM
INTRODUCTION
Over the past century, we have learned how to create specialized materials that meet our specific needs for strength, durability, weight, flexibility, and cost. However, with the advent of smart materials, components may be able to modify themselves, independently, and in each of these dimensions. Smart materials can come in a variety of sizes, shapes, compounds, and functions. But what they all share- indeed what makes them "smart"-is their ability to adapt to changing conditions. Smart materials are the ultimate shape shifters. They can also alter their physical form, monitor their environment, and even diagnose their own internal conditions. They can also do all of this while intelligently interacting with the objects and people around them. More boldly, it is highly likely that once smart materials become truly ubiquitous-once they are seamlessly integrated into a webbed, wireless, and pervasive network -smart materials will challenge our basic assumptions about, and definitions of "living matter."
A smart fluid developed in labs at the Michigan Institute of Technology
IMPORTANCE
In certain respects, smart materials are an answer to many contemporary problems. In a world of diminishing resources, they promise increased sustainability of goods through improved efficiency and preventive maintenance. In a world of health and safety threats, they offer early detection, automated diagnosis, and even self-repair. In a world of political terrorism, they may offer sophisticated biowarfare countermeasures, or provide targeted scanning and intelligence- gathering in particularly sensitive environments. In general, smart materials come in three distinct flavors: passively smart materials that respond directly and uniformly to stimuli without any signal processing; actively smart materials that can, with the help of a remote controller, sense a signal, analyze it, and then "decide" to respond in a particular way; and finally, the more powerful and autonomous intelligent materials that carry internal, fully integrated controllers, sensors, and actuators.
USES & APPLICATIONS
The components of the smart materials revolution have been finding their way out of the labs and into industrial applications for the past decade. As yet, they fall into several classes and categories: piezoelectrics, electrorestrictors, magnetorestrictors, shape-memory alloys, and electrorheological fluids. What these materials all have in common is the ability to act as both sensors and actuators. In some cases, when a force is applied to these smart materials, they "measure" the force, and "reverse" the process by responding with, or creating, an appropriate counter force. In other cases, the materials are populated by sensors that detect environmental conditions within the material itself. When conditions cross designated thresholds, the materials then send a signal that is processed elsewhere in the system. For instance, "smart concrete"-under development at the State University of New York at Buffalo-would be programmed to sense and detect internal hairline fissures. If these conditions are detected, the smart material would alert other systems to avoid a structural failure. Smart materials are currently used for a growing range of commercial applications, including noise and vibration suppression (noise-canceling headphones); strain sensing (seismic monitoring of bridges and buildings); and sensors and actuators (such as accelerometers for airbags). A number of companies, including The Electric Shoe Company and Compaq, are also exploring the use of smart materials. The Electric Shoe Company is currently producing piezoelectric power systems that generate electric power from the body's motion while walking. Compaq is investigating the production of special keyboards that generate power by the action of typing. Descriptions of applications for the smart materials mentioned above suggest that their impact will be broadly felt across industries.