A new room-temperature, in situ polymerization process to produce microneedles (see figure), which can encapsulate functional bioniolecules and dissolve within minutes, is presented. The dissolution rate and mechanical strength of these polymer microneedles can be tailored by changing monomer composition and microneedle geometry. Drug delivery using micrometer-scale needles that dissolve in the skin could eliminate the pain and dangers of hypodermic needle use.