Capillary Rise Modeling and Fabrication of Crown-shaped Microneedle Array for Blood Extraction

Crown-shaped microneedle or quadruplets-microneedle fabricated by synchrotron radiation deep x-ray lithography for blood extraction was developed and has been introduced recently. Since the phenomenon driven a blood extraction process of the quadruplets-microneedle is capillary force, a study of capillary phenomenon or surface tension to suit our microneedle shape was pursued. In the array of quadruplets-microneedle, there were four open-sided grooves connected to all neighbored needles. The higher the capillary rises, the faster the liquid flow through the channel. A geometric calculation of the volume of liquid that can be stored in the microneedle suggests that without the grooves, total amount of liquid extracted by the array of 1024 microneedles is about 0.5 µl whilst the amount of liquid increasing to 0.9 µl with the groove arrays. The flow of liquid by capillary rise was modeled by two configurations of the groove of microneedle; the open-side groove and vertical rectangular tube which is in the center of the microneedle connecting the 4 open-side grooves. The result of simulation was conformable to the experimental data. The numerical simulation method of blood extraction process using the microneedle is discussed