Bio-inspired clamping microneedle arrays from flexible ferrofluid-configured moldings

Microneedle (MN) arrays have demonstrated value for cosmetics, diagnosis, transdermal drug delivery, and other biomedical areas. Much effort has been devoted to developing simple stratagem for creating versatile moldings and generating functional MN arrays. Here, inspired by the serrated microstructure of mantises' forelegs, we present a novel serration-like clamping MN array based on ferrofluid-configured moldings. Benefiting from the flexibility and versatility of ferrofluids, negative microhole array moldings with various sizes and angles toward the midline could be created easily. The corresponding biocompatible polymer MN arrays with both isotropic and anisotropic structures could then be produced feasibly and cost-effectively by simply replicating these moldings. It was found that the resultant serrated clamping MN arrays had the ability to adhere to skin firmly, enabling them to be used over a relatively long time and while the recipient was moving. This proposed technology performed well in minimally invasive drug administration and sustained glucocorticoids release during treatment for imiquimod-induced psoriasis in mice. These features indicated that such MN arrays could play important roles in wearable transdermal drug delivery systems and in other applications.