Reverse milling–sputtering technology to develop scalable microneedle patches for analgesia

With the burst of pandemic disease in recent years, the demand of microneedle patches (MNPs) has increased rapidly for patient-friendly therapeutic treatment to alleviate the patient suffering. Traditional fabrication processes are complicated and time-consuming, greatly limiting their biomedical applications. To obtain MNPs with designable types for clinic needs, a reverse milling-sputtering technology (RMST) was developed in this work to fabricate scalable masters with gold sputtering for better demoldability. The RMST simplicity allowed for the encapsulation of the clinical analgesic lidocaine into the cryo-MNP (C-MNP), which delivered the drug through the skin to achieve the analgesic efficiency of 96.3%, implying the great potential for clinic analgesia. In addition, RMST also enables the fabrication of MNPs with well-defined shape (50-μm tip diameter), a large area of 35×35 mm2 and various polymer materials. RMST can be a scalable and cost-effective strategy to develop MNPs with individual design, holding great potential for transdermal therapy.