SquidLondon is a young innovative company based in London that is conducting experiments with smart materials and textiles to create a range of innovative color-changing products.

I find their water-reactive umbrellas quite lovely. Using hydrochromic inks, the white patterns in the umbrella fill with color when wet. Hydrochromic inks work in a similar fashion to thermochromic and phtochromic inks. Instead of reacting to heat or UV light, they shift color in response to water.

Unfortunately, the umbrellas are a limited run and they seem to be sold out.

Another lovely project that uses smart inks is Yun Ding's Aqua Chameleon swimsuit.
Her swimsuit pattern gradually transforms from a geometric print into a decorative pattern under varying environmental conditions. I'm not sure if the above swimsuit reacts to water and sunlight — conceptually, either of the two (or combination thereof) would work.

Why is this important?
I believe the next stage is to combine a number of these smart inks to work together to create reactive skins. Wouldn't it be fantastic to design a facade of a building with all three of these smart inks — so the building's skin changes pattern in accordance to its environmental conditions? Even a simple "environmentally-aware" wearable would be quite nice.