It's inspired by old grimoires like the Key of Solomon, books on the occult that were themselves inspired by older Kabbalistic and Alchemical texts. I can't tell you exactly what each symbol means, and honestly I doubt anyone could unless they were a specialist of these texts. However Miura based himself on a protective talisman to create this one, so whatever meaning there is to it is unlikely to be negative.
That being said, I don't think it'll work well as a tattoo given how small the characters are.