Smart Materials

Abstract

AbstractFrom a technical and simple point of view a smart material is a material that responses to its environments in a timely manner. To expand on this definition a smart material is one that receives, transmits, or processes a stimulus and responds by producing a useful effect, which may include a signal that the material is acting upon it. Stimuli may include strain, stress, temperature, chemicals, an electric field, a magnetic field, hydrostatic pressures, different types of radiation, and other forms of stimuli. Transmission or processing of the stimulus may be in the form of an absorption of a photon, of a chemical reaction, of an integration of a series of events, of a translation or rotation of segments within the molecular structure, of a creation and motion of crystallographic defects or other localized conformations, of an alteration of localized stress and strain fields, and of others. The useful effects produced could be a color change, an index of refraction change, a stress or strain distribution change or a volume change. Also, incorporation within the definition of smart materials is the ability to be reversible.Under the proper set of environments and circumstances all materials are smart and depict smart behavior at some point during their life cycle. Some examples of technically smart behaving materials given in this article are piezoelectric materials, electrostrictive materials, magnetostrictive materials, electrorheological materials, magnetorheological materials, thermoresponsive materials, pH‐sensitive materials, uv‐sensitive materials, smart polymers, smart gels (hydrogels), smart catalysts, and shape memory alloys.