Passive smart materials

Passively smart materials with self-repairing or stand-by characteristics to withstand sudden changes. 

Dry, C.M. (1993) Passive smart materials for sensing and actuation. J. Intell. Mater. 

Passive heat-transfer enhancement techniques, retrofitted, 13 267 Passive mixers, in microfluidics, 26 966, 967 Passive noise detectors, 11 673 Passive nondestructive tests, 17 416, 425 Passive reactors, 17 555 Passive sensing materials, 22 706-707 Passive smart textiles, 24 625 Passive solar collection, silica aerogel application, 1 761-762 Pasta products, 26 278 Paste-extrusion process, 18 301-302 Paste forming, ceramics, 5 651 Paste inks, 14 315-316... 

Hydrogels act in biosensors not only passively as immobilization matrix but also as responsive (smart) material. Current uses for smart hydrogels in the bioanalytical and biomedical field are... 

Smart textiles can be defined as textiles that are able to sense and respond to changes in their environment. They may be divided into two classes passive and active smart textiles. Passive smart textiles have the ability to change their properties according to an environmental stimulation. Shape memory materials, hydrophobic or hydrophilic textiles, etc. are part of this category. 

Textiles are not only to protect/cover or skin but show self-expression, taste, and personality of the wearer. They can also demonstrate socioeconomic status and cultural movements. Moreover, in the modem fashion world, textiles are highly relied on for their beauty and aesthetic appeal. Recent advancements in wearable devices have extended the functionality of textile materials to smart textiles. Now the term smart textiles is referred to as active or passive depending on the placement of actuators. If the actuator is embedded in the textile, then it is active otherwise is passive. Smart textiles play a key role in our day-to-day life, including the fields of health monitoring, personal trackers, military use, education, home appliances, transportation, gaming, entertainment, and music. Table 9.3 shows the applications of smart/inteUigent textiles to various areas. 

Metal oxide sensors (MOS), smart, 22 717 Metal oxide supported catalysts, 5 336-337 coke formation on, 5 267—270 Metal passivation, in industrial water treatment, 26 137 Metal peroxides, 18 410 Metal phosphates, tertiary, 18 840 Metal-phosphorus alloys, 19 59 Metal phthalocyanines, electrochromic materials, 6 572t, 576-577 Metal prefinishing, detersive systems for, 8 413t... 

Some mixed conductors, i.e. electronic and ionic, into which ions can be rapidly and reversibly inserted can undergo a colour change. This is, for example, the case of the hydrogen bronzes , mentioned earlier in this book. The colour change can be either from transparent to coloured or from one colour to another. This phenomenon, which can be produced electrochemically, is called electrochromism. It is broadly defined as the production of an absorption band in a display material caused by an applied electric field or current. Such a property is currently under intensive study because of its potential use for passive information display glare-free rearview mirrors for automotives " , solar control windows or smart windows " , thermal sensors and projection systems if matrixable. 

In the future, armoured vehicles could be better protected against conventional, non-conventional and NATO-certified ammunitions by using adaptable armour. The shape of an armoured vehicle could be made auto-adaptable so that it could change form when threats are detected by sensors. This would enable a vehicle to actively manage mechanical stress and energy absorption during an impact. Different smart active and passive materials could be used to resist various types of ballistic impacts. 

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