Design and implementation of MEMS based microneedles for biomedical applications

This paper addresses the practical design and implementation MEMS (microelectro-mechanical system) based in-plane silicon microneedles for transdermal drug delivery and/or blood sampling for biomedical and biotechnology applications. The characteristics of in-plane microneedles are far more reliable than out-of-plane microneedles for transdermal drug delivery and blood sampling. In order to obtain the sample of blood from the subcutaneous fat layer, which occurs at a distance of 2000 to 4000 /spl mu/m below the skin surface, the length of our MEMS based in-plane microneedle have been set at 3000 /spl mu/m. This microneedle length is impractical for out-of-plane microneedles. Drug delivery and blood samplings place requirement in terms of minimal needle dimensions and force withstanding capabilities, which are inversely related to each other. The strength of the microneedles has been examined analytically and modeled using finite element modeling tools. Through performance analysis it is shown that the proposed design is a significant improvement over existing microneedles.