Low cost and cleanroom free fabrication of microneedles
We present a facile, low cost and cleanroom free technique for the fabrication of microneedles using molds created by laser ablation. Microneedle mold with high aspect ratios is achieved on acrylic sheet by engraving a specific pattern of crossover lines (COL) using CO2 laser cutter. Ablating COL pattern on the acrylic sheet creates a sharp conical shape in the center of the design. We have shown that a variety of microneedle shapes with different heights and tip angles can be easily achieved by changing the number and the length of the COL. Polydimethylsiloxane (PDMS) microneedles were fabricated by casting the PDMS on the mold. The resulted PDMS microneedles are oxygen plasma treated and then silanized. Another PDMS layer is casted on PDMS microneedles and detached after curing. The silanization prevents those two layers of PDMS from bonding to each other and makes them easily detachable. After detachment of the PDMS mold of microneedles, the mold is used to fabricate degradable polyvinyl alcohol microneedle patch suitable for transdermal drug delivery. The release kinetics of the needles are also shown and discussed in order to prove the applicability of the needles. A low cost method to make microneedles for non invasive drug delivery across the skin has been devised by a team in the United States. By forming microchannels in the skin, microneedles allow drugs such as insulin to be administered without a painful injection and with improved efficacy. However, conventional methods for fabricating microneedles are expensive, requiring cleanroom facilities. Sameer Sonkusale and co workers at Tufts University have developed a method that does not require a cleanroom. They use a laser cutter to fabricate molds for microneedles in an acrylic sheet. The cone shaped molds are created by passing the laser beam through the same point but by different paths, resulting in the greatest amount of material being removed from the central point. The researchers demonstrate their mold by making degradable microneedle patch from various polymers.