Real henna has been used safely for thousands of years, but tattoo stands frequently use an ingredient that poses risks. ->
E-tatts measure skin hydration, temperature and electric signals from muscle and brain and activity, but without the sticky backing. ->
Super-thin, flexible electronic "tattoos" read brain wave activity in a non-invasive way and could be used to control machines. ->
David Teeghman explains why he recently got a tattoo of the Three R's triangle.
In our modern culture, getting a tattoo might be used to represent our freedom of expression, to proclaim our personal identity, as a method of remembrance for our loved ones, or maybe just a way to fit in with the status quo. But in other cultures, such as in prisons, tattoos can be a powerful [.....