The present invention provides microparticles that create permanent tissue
markings, such as tattoos, designed in advance for change and/or removal
on demand, as well as methods for implanting the microparticles in tissue
and changing and/or removing the resulting markings. Colored
microparticles are constructed with specific electromagnetic absorption
and/or structural properties that facilitate changing and/or removing
tissue markings made using the microparticles by applying specific energy
(such as electromagnetic radiation from a laser or flash-lamp) to the
tissue marking site.