Sensors nanoionics

The aim of this chapter is to review the current state of knowledge in ionic materials with crystallite dimensions less than 100 nm, systems which sometimes are referred to as nanoionics. The chapter will detail the preparation, characterization and the important applications of these materials, especially in sensors, solid-state batteries, and fuel cells. Particular focus will be placed on ionic transport in these materials, as this is a topic of considerable contemporary interest, and where conflicting reports exist of enhanced diffusion in nanocrystals. 

It can be seen from the above discussion that the use of nanoionic materials for gas sensors is a natural extension to the findings already reported. Nanosized materials offer advantages in terms of improved sensor response due to the much higher surface areas available. However, the definition of a nano ionic sensor material can be very broad the nanoionic component of the sensor material might refer to the bulk majority phase, but alternatively it could refer to a dispersed catalytic or dopant phase, or even a combination of both. 

The theory and experiments of lyotropic and biomembrane flexoelectricity are reviewed. Flexoelectricity is a reciprocal relation between electricity and mechanics in soft lyotropic systems, i.e., between curvature and polarization. Experimental evidence of model and biomembrane flexoelectricity (including the direct and the converse flexoelectric effects) is reported. The biological implications of flexoelectricity are underlined. Flexoelectricity enables membrane structures to function like soft micromachines and nanomachines, sensors and actuators, thus providing important input to nanoionics apphcations. Nanobio examples include membrane transport, membrane contact, mechanosensitiv-ity, electromotility, hearing, nerve conduction, etc. 

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