Abstract
Micro investment molding combines traditional injection molding with investment casting to create hollow parts on the microscale. Silicon micromolds are manufactured using photolithography and reactive ion etching. Then, a sacrificial element is placed in the mold. Plastic is injected into the mold and around the sacrificial element using an injection molding press. After removing the plastic part from the mold, liquid etchant dissolves the sacrificial element leaving a hollow plastic part. To demonstrate the process microneedles were formed. Using 32 μm diameter aluminum bond wire as the sacrificial element hollow, in-plane, microneedles were formed out of Cyclic Olefin Copolymer (Ticona Topas®). The longest needle has an overall length of 280 μm, cross-sectional dimensions of 130 μm × 100 μm and an approximate inner diameter of 35 μm.
