Polymer-Based Microneedles for Decentralized Diagnostics and Monitoring: Concepts, Potentials, and Challenges

Owing to their ability to breach the skin in a minimally invasive manner, microneedles (MNs) have seen increased interest for potential diagnostic applications. This is particularly true of polymeric MNs, as the structural and functional properties of the polymer materials used in their fabrication can provide unparalleled advantages and open the door to the diagnostic and monitoring strategies of the future. Polymeric MNs used for diagnostic applications can be broadly divided into swelling MNs for the extraction of dermal interstitial fluid (ISF), surface-functionalized MNs for direct analyte detection, and dissolving MNs for the delivery of diagnostic agents to the skin. In this perspective, we use emblematic examples to highlight the major recent advances in this field and provide commentary and insight into the potential opportunities and remaining challenges faced by each of these MN classes, with a specific focus on the role of materials research in the further development of this field.