Microneedle devices typically consist of hundreds, or even thousands, of tiny microscale needles that are spaced into an orderly array of columns and rows.
Each microneedle is just long enough to break through the outer layer of a person's skin, and is thinner than a human hair.
By itself, a microneedle could deliver just a tiny amount of medication. But thousands can deliver a considerable amount.
Microneedles can inject medicine without causing pain because they are so short they only penetrate the stratum corneum of your skin-and do not reach your pain receptors, which are slightly deeper.
Even if they do reach the pain receptors, the size and spacing of the needles prevents them from triggering pain signals.
The tiny size of the needles also makes them far less damaging to skin tissue than a standard hypodermic needle.