| abstract |
A microneedle array is manufactured using a mold preparation procedure that begins by placing an optical mask over a layer of PMMA material, exposing the PMMA material to x-rays, then developing using a photoresist process. The remaining PMMA material is then electroplated with metal. Once the metal has reached an appropriate thickness, it is detached to become a metal mold that is used in a microembossing procedure, in which the metal mold is pressed against a heated layer of plastic material. Once the mold is pressed down to its proper distance, the plastic material is cooled until solidified, and the mold is then detached, thereby leaving behind an array of microneedles. If the microneedles are hollow, then an additional procedure is used to create through-holes all the way through the underlying substrate material using laser optical means. Another procedure to create plastic microneedles begins with a two-layer laminate structure of biocompatible material. A metallic mold created is pressed down all the way through the top layer of the heated laminate, and partially into the bottom layer to ensure that the top layer is entirely penetrated. Once the laminate material has then been cooled, the mold is removed and the top layer is detached from the bottom layer. This top layer will now have holes that will be further operated upon by a microembossing procedure using a different mold which creates hollow microneedles having through-holes in its substrate. A further manufacturing process to make hollow microneedles is to create shear forces along the inner surfaces of a cylindrical opening of a hollow microneedle during its de-molding step while the microneedlec array material is being cooled. The amount of shear can be controlled by the cool-down temperature, and if properly done will result in hollow microneedles having sharp edges along their upper surfaces at their tips. |