Not only are injections painful, they can sometimes leave spots and even risk infection, which makes many people nervous. Recently, American and Italian researchers have developed a microneedle with strong Tissue Adhesion. The microneedle is minimally invasive, painless and easy to use.

Microneedles are tiny needles only a few hundred micrometers in length, and have received widespread attention because they do not cause intense pain. However, the microneedles developed at present all have low tissue adhesion, which affects their availability as long-term drug delivery or biosensor tools.

A team from rutgers university and the university of Pisa in Italy, inspired by microscopic structures found in nature, such as tiny hooks for parasites and barbs on bees’ legs, used 4D printing to create micrones with Strong Tissue Adhesion. The so-called 4D printing method adds the dimension of time to 3D printing, allowing the printed smart material to change shape at a set time.

Unlike traditional microneedles, this new type of microneedle has many barbs that interlock with tissue when inserted, thus enhancing adhesion. The density and bending curvature of these barbs can be controlled by printing parameters and material composition. Using chicken tissue as a model, the researchers tested the tissue adhesion of the microneedles. The results showed that the new microneedles had 18 times more tissue adhesion than the barb free microneedles, which could ensure sustained drug release in the tissues.

The researchers say the 4d-printed microneedle array is minimally invasive, painless and easy to use as an alternative to traditional injectable needles for medical tasks such as drug delivery and blood collection.

The research was published recently in the journal advanced functional materials.