A novel microneedle array integrated with a PDMS biochip for microfluid systems

This paper reports a novel single-crystal-silicon microneedle array, its mechanical properties, its integration with a polydimethylsiloxane (PDMS) biochip, as well as in vitro and in vivo test results. The fabricated microneedle arrays have integrated microchannels, which are fabricated by using the processes of anisotropic dry etching, isotropic dry etching, and trench-refilling. The microchannel diameter is about 20 /spl mu/m. The 2 mm-length microneedle shaft is strong enough to endure 12.6 gf (=23.5 mN) of vertical loading. The fabricated microneedles are planar, which make it easy to integrate with biofluidic devices. As an in vitro test, the microneedle array is integrated with a PDMS biochip, and black ink is injected into a methanol-filled petri dish. The microneedle is tested in vivo by penetrating the mouse skin and precisely pricking into the small vein in the mouse tail.