Injection molding of microprobe array parts

The sharp tips of a microprobe array installed in an endoscope can penetrate cancer cell in stomach or intestines, and then deliver drug or gene into cells for treatment. In this study, two microprobe masters were fabricated. The first model is a single-crystal silicon based microprobe array (height = ∼80 μm, aspect ratio ∼1.7, density = 780/cm²), which was fabricated by KOH wet etching. The second model is a stainless steel master, which was fabricated by WEDG and assembled with acupuncture needles (height = ∼890 μm, aspect ratio ∼4.5). Nickel was chosen as the material for electroforming mold insert. High flow rate PC and general purpose PP were used to mold microprobe parts by injection molding and injection compression molding. In the experiment, it was successful to duplicate microprobes with PP by injection compression molding. Taguchi method was used to find the close to optimal processing parameters and the contribution of the injection compression molding parameters.