Last year, I mentioned speculation by some scientists that it might be possible to create LED tattoos. There's been progress in the field since that time. Researchers have developed arrays that are 2.5 micrometers thick and 100 micrometers across:
Link via DVICE | Image: Nature Materials
The PDMS substrate is flexible enough that the circuits can still function even if twisted or stretched by even as much as 75 percent.[...]
The researchers successfully tested the LEDs by integrating a sheet into the fingertip of a vinyl glove, which they then immersed in soapy water, and they have also implanted an array beneath the skin in an animal model.
Link via DVICE | Image: Nature Materials
Do we really need LED tattoos badly enough to justify causing animals to suffer?
Or are they wanting rats with signal lights to follow behind the rat pulling the wagon with its brain?
http://www.99fallingapples.com/design-concept/intelligent-curtain-to-protect-your-privacy/