3D laser lithographic fabrication of hollow microneedle mimicking mosquitos and its characterisation

Abstract

Microneedles mimicking mosquitos were fabricated by employing a three-dimensional laser lithography. An ultra-precision three-dimensional laser lithography system 'Nanoscribe GT' is employed. On the basis of two-photon absorption phenomenon, an extremely small space of less than 200 nm in the photocurable polymer material is cross-linked, where a laser beam is focused. The total cross-linked space finally emerges after development process. First a bundled needle comprising three parts was fabricated, which imitates central hollow labrum of sucking blood, and two side solid maxillae having jagged edges. Second, a practical needle comprising two parts was proposed and fabricated. The functions of three-piece mosquito's proboscis (one labrum and two maxillae) are integrated to two parts. Each half-needle has semi-circular channel and jagged edges. By combining the two-halves, one hollow microneedle is realised. Alternative motion like mosquito maxillae is possible. Fluid is introduced into the channel through small holes in the wall, and is drawn up by capillary force. Reduction in number of microneedles simplifies both fabrication process and drive system for puncturing. It was experimentally confirmed that the needle successfully penetrates PDMS skin. The effectiveness of alternative motion of two parts with 90° phase to each other was also investigated.