Laser Fabrication of Jagged-Shaped Stainless Steel Microneedle Imitating Mosquito’s Maxilla

The demand for the development of low-invasive injection needles or needle-shaped tools for applications in medical practices, such as blood sampling and blood sugar level tests, are growing. We observed a mosquito’s penetration motions and fabricated low-invasive microneedles from 30- μ m-thick stainless steel foil, imitating a pair of the mosquito’s maxillae. In our earlier studies, we attempted to fabricate needle tips with jagged portions by using a specially ordered machine tool and sharpening them by electrolytic etching, but found it difficult to maintain the needle tips in a jagged shape. However, in this study we successfully fabricated microneedles (70 μ m in width and 2.2 mm in length) with three-dimensionally sharpened tips (angled at 15° on the upper surface and sides) by machining 30- μ m-thick stainless steel foil by femtosecond laser. Femtosecond laser machining can be applied to any type of material and can fabricate any desired three-dimensional structures by changing the angles at which the materials are set.