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1、 For some time smart materials found their primary use in interesting but specialized engineering and scientific applica- tions, or, at the other end of the spectrum, in novelty applications (e.g., the endless numbers of thermochromic coffee cups that change colors when filled). Recently, a whole ho
2、st of new products have found their way into the market some interesting, some not as designers began to discover them. This chapter briefly looks at smart materials from a product-oriented perspective. In order to understand smart material use in a product context, we must first step back and look
3、at smart materials from a broad phenomenological perspective. What do they actually do in terms that are of interest to a designer? What effects or actions are needed or wanted? After this review, we will look more directly at the results of dramatic changes that have occurred in production technolo
4、gies that have ushered in new product forms or made existing ones less expensive. For example, there have been many amazing technological improvements in the production of thin films. Many exciting smart products have become possible not so much because of innovations at the basic materials level, b
5、ut rather because of improved manufacturing technologies. Many of the produc- tion technologies developed have allowed many smart materials that were heretofore only laboratory curiosities to become usable to the design community. This chapter thus focuses on identifying the actions and effects that
6、 are possible via smart materials, and then on the technologies that allow them to be implemented. The marriage between these two streams has indeed become a happy one.6.1 A phenomenological perspectiveAs we have seen, most smart materials actually work at the micro-scale (smaller than a micron) and
7、 are thus not visible to the human eye. Nevertheless, the effects produced by these mechanisms are often at the meso-scale (approximately a centimeter) and macro-scale (larger than a meter). Whereas the physical mechanism how the material works is entirely138Smart products6Smart productsdependent up
8、on the material composition; the phenomen- ological effects the results produced by the action of the material are determined by many things independent of the material composition including quantity, assembly con- struction, position and environment. As a result, very similar effects can often be p
9、roduced from seemingly dissimilar materials. We can categorize these effects in terms of their arena of action, which could be considered as analogous to an architects intention what do we want the material to do? The smart materials that we use can produce direct effects on the energy environments
10、(luminous, thermal and acoustic), or they can produce indirect effects on systems (energy generation, mechanical equipment). The following categories broadly organize smart materials according to their effects that are of direct interest to designers. Note that some materials can be deployed to have
11、 multiple effects depending on the energy input.LUMINOUS ENVIRONMENTTransparency and color change This is one of the largest classes of smart materials, as many different mechanisms give rise to a wide variety of color conditions. Color is understood by the human eye in two ways by the spectral comp
12、osition of transmitted light through a translucent surface to the viewer, or by the spectral composition of reflected light from a surface to the viewer. Translucent materials may change their total transmissivity, whether from opaque to transparent. Suspended particle and electrochromic technologie
13、s do this, as well as photochromics and thermotropics. Alternatively, they may selectively change the color that is being transmitted (liquid crystal, chemo- chromic). Reflectivities may also be changed, from one color toanother(alsophotochromicandchemochromic)or through several colors depending on
14、the environmental inputs (thermochromic). In glasses and films, reflected or transmitted colors may change according to the angle of view (diochroic effects). Various light control objectives, e.g., glare reduction,canalsobeachievedthroughvarioushigh performance optical materials.Light emission The
15、conventional means for producing light depend upon inefficiency in energy exchange: incandescent light is pro- duced when a current meets resistance in a wire (thereby producing infrared radiation), and fluorescent devices dependSmart Materials and New TechnologiesSmart products139upon the resistanc
16、e of a gas (thereby producing ultraviolet radiation). Light emission from smart materials is based on wholly different mechanisms, and thus is not only more efficient, but more divisible and controllable. Light can be produced of any color (electroluminescent, light-emitting diodes), of any size, intensity or shape (also electrolumines- cent). Light can be produced in direct response to environ- mental conditions (chemoluminescent, photoluminescent) and light can also be st
