Gradient electrochromic

Yao, Z., et al., Aligned coaxial tungsten oxide-carbon nanotube sheet a flexible and gradient electrochromic film. Chemical Communications, 2012. 48(66) p. 8252-8254. 

It is possible, however, that the electrochromic response of some styrylpyridi-nium probes, for example, RH421 (see Fig. 2), is enhanced by a reorientation of the dye molecule as a whole within the membrane. There is a steep gradient in polarity on going from the aqueous environment across the lipid headgroup region and into the hydrocarbon interior of a lipid membrane. Therefore, any small reorientation of a probe within the membrane is likely to lead to a change in its local polarity and hence a solvatochromic shift of its fluorescence excitation spectrum. Such a... 

---