Surface impedance changes, chemical

Chemical Microsensors Based on Surface Impedance Changes... 

Skin tissues isolated from rats, rabbits, and humans have been monitored in vitro to predict penetration and irritation. The rat epidermal slice technique has been validated as a screen for corrosive substances. The electrical impedance changes as the integrity of the stratum corneum is altered. The use of this technique to predict irritancy is being investigated in the United Kingdom. Another method studies enzyme changes when a substance is applied to a slice whose lower surface is bathed in culture medium. Enzyme changes separate irritant and nonirritant chemicals. 

An emerging subdiscipline of tribological simulation involves the study of tribochemical reactions—that is, reactions that are activated by pressure and shear. These reactions alter the structure of lubricants and films that are used to protect surfaces from wear. Understanding the effects of these reactions on the intended behavior of these films is of utmost importance. However, simulation studies of tribochemical reactions have been impeded by the difficulty in accurately describing changes in chemical bonding. In a limited number of cases, this can be achieved with the use of reactive FFs, as noted above, whereas in other cases, one must resort to expensive quantum chemical calculations. In this section, we will describe two studies where such methods were used to examine tribochemical reactions. 

When the size of a material is reduced to the nanoscale, their physical and chemical properties are dramatically changed. The separated nanostructure of polymer composites is expected to bring important improvements for polymer electronics because the size reduction of materials increases the contact surface area and lowers the interfacial impedance between the electrode and the electrolyte, and decreases the transport pathways for both electrons and ions (Shi et al., 2015). In addition, the mechanical properties for strain accommodation as well as the flexibility will be improved. A variety of nanostructures of polymer composites have been developed including zero-dimensional nanoparticles, one-dimensional nanowires/rods/belts, two-dimensional nanosheets/plates, and three-dimensional porous frameworks/networks. 

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