Laser fabrication of high aspect ratio thin holes on biodegradable polymer and its application to a microneedle

The present paper reports the fabrication of long thin holes with a high aspect ratio of 100 (diameter: 10 μm, depth: 1 mm) in biodegradable polymer material (polylactic acid, referred to herein as PLA) using a UV excimer laser. Holes having diameters of 10, 20 and 50 μm are fabricated from the side surface of a PLA sheet, and their fabricated shapes are observed using an optical microscope. These holes are compared with holes fabricated in other polymer sheets. It is proven that a long thin hole can be fabricated in PLA material, although at a lower fabrication rate compared that for epoxy material. This laser fabrication is applied to a PLA microneedle, which is fabricated by the micromolding technique. A hole is fabricated along the centerline of the newly developed microneedle, and it is confirmed experimentally that blood plasma is taken into this hole by capillary force.