Proof of Concept of 3D-Printed Microneedles: Bioinspired 4D Microneedles

Four-dimensional (4D) printing has introduced new possibilities for the development of dynamic and adaptive microneedle (MN) systems, enabling time-dependent functional transformations in response to external stimuli. This chapter presents a proof-of-concept overview of bioinspired 4D-printed microneedles, highlighting recent innovations in shape-shifting materials and stimuli-responsive systems for advanced therapeutic applications. Bioinspired design strategies are discussed, focusing on dynamic penetration capabilities and enhanced skin adhesion that improve delivery efficiency and device stability. The chapter further reviews applications demonstrated over the past 5 years, including responsive drug release mechanisms and self-adapting microneedle patches that respond to physiological and environmental cues. Collectively, this chapter illustrates the potential of bioinspired 4D microneedle technologies to enable intelligent, adaptive, and next-generation transdermal delivery platforms.