Characterization of microfabricated microneedles for sampling

This paper presents the mechanical characterization of the microfabricated in-plant microneedles use for blood sampling. The characterization includes the affects of design variations on the buckling and penetration force of these microneedles. Tests have shown that liquids like blood are drawn into the needle by capillary forces, reducing the need for active pumping. The characteristics of various microneedle design features including varying dimension, varying shaft lengths and specifically tip taper angles/geometries were studied. In this study, the length of the needles varied between 2000 μm and 200 μm. The widest dimension of the microneedle at its base was 210 μm. The tip taper angles and their geometries are determined by bulk micromachining technique. The calculated results reveal that designed microneedles over a range of geometries are capable of withstanding the force of insertion.