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. 2021 Jan 22;12(2):117.
doi: 10.3390/mi12020117.

Optimisation of Design and Manufacturing Parameters of 3D Printed Solid Microneedles for Improved Strength, Sharpness, and Drug Delivery

Sophia N Economidou  1 , Cristiane P Pissinato Pere  1 , Michael Okereke  2 , Dennis Douroumis  3
Affiliations

Optimisation of Design and Manufacturing Parameters of 3D Printed Solid Microneedles for Improved Strength, Sharpness, and Drug Delivery

Sophia N Economidou et al. Micromachines (Basel). .

Abstract

3D printing has emerged as a powerful manufacturing technology and has attracted significant attention for the fabrication of microneedle (MN)-mediated transdermal systems. In this work, we describe an optimisation strategy for 3D-printed MNs, ranging from the design to the drug delivery stage. The key relationships between design and manufacturing parameters and quality and performance are systematically explored. The printing and post-printing set parameters were found to influence quality and material mechanical properties, respectively. It was demonstrated that the MN geometry affected piercing behaviour, fracture, and coating morphology. The delivery of insulin in porcine skin by inkjet-coated MNs was shown to be influenced by MN design.

Keywords: 3D printing; inkjet coating; microneedles; optimisation; stereolithography.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Optimisation of post-printing curing regime in respect to compressive mechanical properties: (a) Digital image of compression specimens for different curing settings, (b) compressive moduli, and (c) yield strengths obtained by specimens subjected to different curing regimes.
Figure 2
Figure 2
Optimisation of the printing angle; (a,b,c) CAD captions; (d,h,l) virtual models of supported MN arrays for 0°, 90° and 45°, where the bottom of the base is adhered to the printing platform; (e,f,g) SEM captions of MNs built at 0°; (i,j,k) SEM captions of MNs built at 90°; and (m,n,o) SEM captions of MNs built at 45°.
Figure 3
Figure 3
Dimensional discrepancies of printed MNs in respect to printing angle; (a) tip diameter; (b) length at the longitudinal axis; and (c) width at the base.
Figure 4
Figure 4
Piercing tests in porcine skin; (a) force/needle vs displacement data for all designs; (b) insertion force/needle; digital images of the porcine skin samples after piercing with (c) cone, (d) pyramid, and (e) spear MNs; and (f,g,h) post-testing SEM images of the MN tips.
Figure 5
Figure 5
MN fracture testing: (a) Force vs. displacement curve, featuring magnified captions at the fracture points and (b) fracture forces.
Figure 6
Figure 6
CD spectra for insulin and insulin-polymer carriers.
Figure 7
Figure 7
Inkjet coating; (a,b) static contact angle of inkjet droplet upon impingement on the MN surface for convex (cone) and flat (spear and pyramid) surfaces; (c,d,e) scheme of the coating configuration for cone, pyramid, and spear MNs; and (f,g,h) SEM images of the coated MNs.
Figure 8
Figure 8
Cumulative release profiles for insulin delivered by 3D printed coated MNs with polymers as carriers; (a) poloxamer; (b) Polyvinylpyrrolidone (PVP).
See this image and copyright information in PMC

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