Effect of microneedle design on pain in human volunteers

Clin J Pain. 2008 Sep;24(7):585-94. doi: 10.1097/AJP.0b013e31816778f9.


Objectives: To design microneedles that minimize pain, this study tested the hypothesis that microneedles cause significantly less pain than a 26-gauge hypodermic needle, and that decreasing microneedle length and the number of microneedles reduces pain in normal human volunteers.

Methods: Single microneedles with lengths ranging from 480 to 1450 microm, widths from 160 to 465 microm, thicknesses from 30 to 100 microm, and tip angles from 20 to 90 degrees; and arrays containing 5 or 50 microneedles were inserted into the volar forearms of 10 healthy, human volunteers in a double-blinded, randomized study. Visual analog scale pain scores were recorded and compared with each other and to the pain from a 26-gauge hypodermic needle.

Results: All microneedles investigated were significantly less painful than the hypodermic needle with microneedle pain scores varying from 5% to 40% of the hypodermic needle. Microneedle length had the strongest effect on pain, where a 3-fold increase in length increased the pain score by 7-fold. The number of microneedles also affected the pain score, where a 10-fold increase in the number of microneedles increased pain just over 2-fold. Microneedle tip angle, thickness, and width did not significantly influence pain.

Discussion: Microneedles are significantly less painful than a 26-gauge hypodermic needle over the range of dimensions investigated. Decreasing microneedle length and number of microneedles reduces pain.

Publication types

  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural

MeSH terms

  • Adolescent
  • Adult
  • Double-Blind Method
  • Equipment Design
  • Equipment Failure Analysis*
  • Female
  • Humans
  • Injections / adverse effects*
  • Male
  • Needles / adverse effects*
  • Pain / diagnosis*
  • Pain / etiology*
  • Pain / prevention & control
  • Pain Measurement*