Additive manufacturing of microneedles for sensing and drug delivery

ABSTRACT

Introduction

Microneedles (MNs) are miniaturized, painless, and minimally invasive platforms that have attracted significant attention over recent decades across multiple fields, such as drug delivery, disease monitoring, disease diagnosis, and cosmetics. Several manufacturing methods have been employed to create MNs; however, these approaches come with drawbacks related to complicated, costly, and time-consuming fabrication processes. In this context, employing additive manufacturing (AM) technology for MN fabrication allows for the quick production of intricate MN prototypes with exceptional precision, providing the flexibility to customize MNs according to the desired shape and dimensions. Furthermore, AM demonstrates significant promise in the fabrication of sophisticated transdermal drug delivery systems and medical devices through the integration of MNs with various technologies.

Areas covered

This review offers an extensive overview of various AM technologies with great potential for the fabrication of MNs. Different types of MNs and the materials utilized in their fabrication are also discussed. Recent applications of 3D-printed MNs in the fields of transdermal drug delivery and biosensing are highlighted.

Expert opinion

This review also mentions the critical obstacles, including drug loading, biocompatibility, and regulatory requirements, which must be resolved to enable the mass-scale adoption of AM methods for MN production, and future trends.

KEYWORDS:

• 3D printing
• additive manufacturing
• biosensing
• microneedles
• transdermal drug delivery

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Declarations of Interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer Disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Article highlights

• Microneedles (MNs) are a technology that has gained prominence in recent years due to their unique properties, such as self-application, minimal invasiveness, and painless insertion resulting from their microscale size.

• MNs can be categorized into five types, namely coated MNs, solid MNs, dissolving MNs, hollow MNs, and hydrogel-forming MNs.

• Additive manufacturing (AM) is a robust technology that offers the flexibility to manufacture MNs in a single step with a high level of shape complexity, high precision, and cost-efficiency.

• The commonly utilized additive AM techniques for manufacturing MNs encompass fused deposition modeling (FDM), stereolithography (SLA), digital light processing (DLP), two-photon polymerization (TPP), continuous liquid interface fabrication (CLIP), and selective laser sintering (SLS).

• MNs as a drug delivery system offer the advantages of patient-friendly transdermal patches while also providing potential delivery capabilities comparable to hypodermic injections.

• In the realm of diagnosis and monitoring, MNs facilitate the painless collection of interstitial fluid (ISF) while also enabling real-time detection of biologically-relevant analytes.

Additional information

Funding

This paper was funded by the Turkish Scientific and Technical Research Council (TUBITAK) 2214-A.