Silicon-processed microneedles

A combination of surface- and bulk-micromachining techniques is used to demonstrate the feasibility of fabricating microhypodermic needles. These microneedles, which may be built with on-board fluid pumps, have potential applications in the chemical and biomedical fields for localized chemical analysis, programmable drug-delivery systems, and very small, precise sampling of fluids. The microneedles are fabricated in 1, 3, and 6 mm lengths with fully enclosed channels formed of silicon nitride. The channels are 9 μm in height and have one of two widths, 30 or 50 μm. Access to the channels is provided at their shank and distal ends through 40-μm square apertures in the overlying silicon nitride layer. The microneedles are found to be intact and undamaged following repetitive insertion into and removal from animal-muscle tissue (porterhouse steak)