Design of a microneedles array with swellable tips for mechanical interlocking with soft tissues

Tissue adhesive has received great attention due to an increasing clinical need. It has been widely used for wound closure, hemostasis, and fixation of tissues. Moreover, since tissue adhesion is essential for the application of drug delivery patches or medical devices, many research efforts have been devoted to the development of adhesives enabling long-term tissue adhesion in clinical setting. However, it is still challenging to achieve a significant adhesion to soft tissues while minimizing tissue damage. Here we have developed a double-layered microneedle array consisting of a poly(styrene)-block-poly(acrylic acid) swellable tip and non-swellable polystyrene core, achieving mechanical interlocking with tissues. With optimum swellable tip height, the patch-type microneedle adhesive showed enhanced adhesion strength to wet skin compared to a flat patch.