Wire bonded solid metal microneedles: a versatile platform technology for transdermal drug delivery and biosensing

Microneedles are emerging as a promising technology for transdermal drug delivery and biosensing due to their ability to penetrate the skin’s upper layers without interacting with pain-sensitive deeper nervous tissue. This characteristic makes them an attractive alternative to hypodermic needles for various therapeutic and diagnostic applications. However, traditional fabrication methods for microneedles often require complex, multi-step processes that are costly and unsuitable for scalable manufacturing, particularly for metal microneedles, which are ideal for biosensing applications due to their excellent electrical properties. Our group has previously developed a novel low cost and high throughput method of fabricating solid metal microneedles using a modified wire bonding process. In this work, we explore the dual potential of these wire-bonded microneedles for drug delivery and biosensing. For biosensing, we functionalized the microneedles with the glucose oxidase enzyme immobilized within a porous electro-polymer coating. We demonstrated the ability to detect physiologically relevant glucose concentrations through benchtop chronoamperometric measurements in prepared glucose solutions and glucose-soaked porcine skin tissue. Furthermore, we developed a miniaturized hardware interface for these microneedle arrays that will facilitate future development of a wearable microneedle-based glucose sensing system. For drug delivery, we successfully demonstrated that wire bonded solid metal microneedles can be coated with a chitosan hydrogel loaded with the chemotherapeutic agent doxorubicin, thus verifying their potential use as a drug delivery platform. These results highlight the versatility of wire bonded metal microneedles for both drug delivery and biosensing, demonstrating their potential as a scalable platform technology.