Engineering microneedles for biosensing and drug delivery

Microneedles (MNs) are small, minimally invasive devices that typically measure from tens to hundreds of micrometers in length and are usually less than a millimeter in diameter. Their purpose is to pierce the outermost layer of the skin or other tissues to collect bio-fluids or aid in the delivery of medications. MNs are less daunting for individuals with needle phobia, which may enhance patient compliance to treatments. Researchers are developing methods to integrate biosensors onto MN surfaces or incorporate them into the MNs structure to monitor analytes in bio-fluid in real time. The research community is also exploring various designs, materials, and fabrication methods to enhance medication delivery, stability, and patient comfort. In general, MNs development is an evolving field, characterized by continuous research endeavors that seek to resolve technical obstacles, enhance device functionality, and progress toward clinical applications. Here, we will delve into the methods for engineering MNs, focusing on biosensing and drug delivery. For a better understanding of translational research, we will examine MN designs that have been clinically approved. We will also provide a brief overview of the most important design aspects and go over some potential opportunities for MN development in the future.