Fabrication and testing analysis of tapered silicon microneedles for drug delivery applications

• Tapered silicon microneedles are fabricated by an improved cutting method.
• Force testing about these microneedles indicates that they pierced into skins easily.
• A 7 × 7 microneedles patch is selected to be employed to experiment drug delivery.
• The permeation of calcein through skins can be obviously improved by this patch.

Drug delivery plays an important role in the treatment of disease, and the equipment used for drug delivery has a great impact on the delivery efficiency of drugs. Recently developed for drug delivery, the new microneedle apparatus has the potential to improve this efficiency. In this study, an incorporated micro-fabrication process is proposed for the formation of tapered silicon microneedles. First, a dicing saw with one beveled blade and one right blade is used to directly cut silicon wafers into the basic shape of tapered microneedles. Next, a chemical etching process containing a dynamic step and static step is deployed to refine the basic shape and form sharp and tapered microneedles 400 μm in length and 600 μm in width between the tips of two microneedles. A variety of microneedle array patches are fabricated to investigate their ability to pierce artificial skin with forces ranging from 0.1 N to 10 N. The percutaneous experimental results show that the permeation rate of a 7 × 7 microneedle array patch through a treated rat skin is 36 times higher than that for intact skins.

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