Design and evaluation of a pump-free ultrasonic atomization-driven hollow microneedle array for transdermal drug...

A pump-free hollow microneedle drug delivery system driven by ultrasonic atomization was developed for continuous transdermal administration of liquid drugs. The device integrated an ultrasonic atomization unit, a silicone delivery chamber, and a stainless-steel hollow microneedle array. The influences of lumen diameter and chamber configuration on fluid transport performance were systematically evaluated. The results demonstrated that lumen diameter and the positional relationship between the atomizer outlet and needle inlet played critical roles in determining delivery initiation, flow stability, and transport efficiency. Optimized structural parameters enabled more sustained and controllable liquid delivery, while unfavorable geometries led to liquid accumulation and increased flow resistance. In vivo experiments in Sprague-Dawley rats further showed that insulin delivered by the system produced an evident hypoglycemic effect, confirming the feasibility of this platform for transdermal delivery of biomacromolecular therapeutics. These findings indicate that ultrasonic atomization provides an effective driving mechanism for hollow microneedle-mediated drug delivery and highlights its potential application in wearable transdermal therapeutic devices.