Grumpy Old Geeks Topics Smart tattoo ink Topic Smart tattoo ink 2 mentions in 1 episode The hosts discuss experimental ink that changes color in response to health markers. Mentions 277: I Am A Cautionary Tale Sep 3, 2018 1:03:18 Smart tattoo inks, which could monitor your blood sugar levels and another tattoo that can measure dehydration levels. 1:03:39 If the ink detects a shift, it changes colors.