Figure 3.
Effect of microneedle retraction on (a) infusion pressure and (b) pain score as a function of infusion volume. Microneedles were inserted into the skin at T1 = 500 μm (▲), T3 = 1 mm (○) and T6 = 1 mm followed by retraction back to 500 μm (◇). A hypodermic needle T5 (●) was also inserted intradermally. All infusions were performed at the medium saline flow rate of 0.3 mL/min. Visual analog score (VAS) for pain was normalized relative to the pain caused by intradermal insertion of the hypodermic needle. Data are the average of 10 replicates expressed as mean ± SD.