Hacker News new | past | comments | ask | show | jobs | submit login Programmable pigments: Photochromic nanoparticle inks for rewritable tattoos ( cell.com ) 9 points by Bluestein 1 hour ago | hide | past | favorite | discuss help Consider applying for YC's Winter 2027 batch! Applications are open till November 2. Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact Search: