Journal of Micromechanics and Microengineering vol:20 issue:6
Protein drugs, e.g. hormonal drugs, cannot be delivered orally to a patient as they get digested
in the gastro-intestinal (GI) tract. Thus, it is imperative that these kinds of drugs are delivered
transdermally through the skin. To provide for real-time feedback as well as to test
independently for various substances in the blood, we also need a blood sampling system.
Microneedles can perform both these functions. Further, microneedles made of silicon or
metal have the risk of breaking inside the skin thereby leading to complications. SU-8, being
approved of as being biocompatible by the Food and Drug Agency (FDA) of the United States,
is an attractive alternative because firstly it is a polymer material, thereby reducing the chances
of breakages inside the skin, and secondly it is a negative photoresist, thereby leading to ease
of fabrication. Thus, here we present very tall (around 1600 μm) SU-8 polymer-based hollow
microneedles fabricated by a simple and repeatable process, which are a very good candidate
for transdermal drug delivery as well as blood extraction. The paper elaborates on the details
that allow the fabrication of such extreme aspect ratios (>100).