Microneedles give painless shots

The smaller the hypodermic needle, the less it hurts when it pierces skin.

Researchers from the Georgia Institute of Technology have developed ways to manufacture solid and hollow metal, silicon, plastic and glass microneedles that range in size from one millimeter to one thousandth of a millimeter.

The researchers demonstrated that an array of 400 microneedles can be used to pierce human skin, and successfully used a similar micro array to deliver insulin to diabetic rats.

Solid microneedles could eventually be used with drug patches to increase diffusion rates; hollow needles could eventually be used with drug patches and timed pumps to deliver drugs at specific times, according to the researchers.

The hollow needle designs include tapered and beveled tips, and could eventually be used to deliver microliter quantities of drugs to very specific locations.

The researchers' method involves etching microneedle masters from silicon, then using the masters to fabricate micromolds for metal and polymer needles. They made glass microneedles using conventional drawn-glass techniques.

Microneedle-based devices could be on the market within five years, according to the researchers. The work appeared in the November 17, 2003 issue of the Proceedings of the National Academy of Sciences.