Imagine going to your doctor’s office and leaving with a prescription for a tattoo.  You know, to protect your health.  My grandmother would have been shocked. Then again, imagine being able to temporarily turn off your tattoos, making them invisible when you visit your easily shocked grandmother, but then turn them on again when you’re back in your neighborhood.  Both of those ideas may become a reality, with new dynamically changing tattoo inks.  Carson J. Bruns is a Professor of mechanical engineering and technology, arts, and media in the ATLAS Institute at the University of Colorado in Boulder.