Biocompatible all carbon hollow microneedles for effective transdermal delivery

Although transdermal drug delivery has significantly progressed, it is still challenging to identify a biocompatible, mechanically consistent, scalable method. This work offers a novel approach for producing all-carbon hollow microneedles (MNs) using UV photolithography following high-temperature pyrolysis. These MNs, with dimensions of 450 mu m height, 100 mu m external diameter, and 80 mu m internal diameter, had hitherto unheard-of mechanical and functional properties, including a hardness of 5.55 GPa and the capacity to withstand skin resistive pressures of 3.18 MPa without compromising their structural integrity. Compared to previous designs, this new method ensures accurate and consistent hollow conduits, as shown by SEM imaging, and leads to better flow rates of 111.66 mu l min(-1) for deionized water and 134.28 mu l min(-1) for ethanol. Preclinical testing further highlights their outstanding biocompatibility, low tissue inflammation, and high insertion success rates (>90%), making them ideal for real-world applications. By overcoming the drawbacks of conventional materials and methods, this work sets a new standard for carbon microelectromechanical systems technology, paving the way for safer, more effective, and scalable transdermal drug delivery systems.