Analysis of 3D Prints by X-ray Computed Microtomography and Terahertz Pulsed Imaging

Abstract

PurposeA 3D printer was used to realise compartmental dosage forms containing multiple active pharmaceutical ingredient (API) formulations. This work demonstrates the microstructural characterisation of 3D printed solid dosage forms using X-ray computed microtomography (XμCT) and terahertz pulsed imaging (TPI).MethodsPrinting was performed with either polyvinyl alcohol (PVA) or polylactic acid (PLA). The structures were examined by XμCT and TPI. Liquid self-nanoemulsifying drug delivery system (SNEDDS) formulations containing saquinavir and halofantrine were incorporated into the 3D printed compartmentalised structures and in vitro drug release determined.ResultsA clear difference in terms of pore structure between PVA and PLA prints was observed by extracting the porosity (5.5% for PVA and 0.2% for PLA prints), pore length and pore volume from the XμCT data. The print resolution and accuracy was characterised by XμCT and TPI on the basis of the computer-aided design (CAD) models of the dosage form (compartmentalised PVA structures were 7.5 ± 0.75% larger than designed; n = 3).ConclusionsThe 3D printer can reproduce specific structures very accurately, whereas the 3D prints can deviate from the designed model. The microstructural information extracted by XμCT and TPI will assist to gain a better understanding about the performance of 3D printed dosage forms.Electronic supplementary materialThe online version of this article (doi:10.1007/s11095-016-2083-1) contains supplementary material, which is available to authorized users.

X‐ray microfocus computed tomography: a powerful tool for structural and functional characterisation of 3D printed dosage forms

“…An example of such operators is described by Markl et al . and presented in Figure (Markl et al ., ). The workflow allows for the identification of a subvolume within either the μCT which does not overlap with the CAD model (XOR‐XμCT data) and vice versa (XOR‐CAD data).…”

“…CAD) object and rectangles to denote logical operations between the aforementioned sets of data the results of which quantify the printing accuracy. Adapted from reference Markl et al (2017). (c) solidifies liquid resins via UV emission (Stereolithography-SLA) (Wang et al, 2016). These processes inherently create objects with deviations from the ideal designed template for reasons specific to each 3D printing method.…”

“…This enables visualisation of both the external and the internal structure of the objects with exceptional resolution; typical voxel-size in the order of a few micrometres, although for much smaller volumes of interest voxel-size can be < 1 µm. The technique can perform detailed mapping of the external surface of 3D printed dosage forms and assess their porosity, both qualitatively (Alhijjaj et al, 2016;Arafat et al, 2018;Goyanes et al, 2018;Holländer et al, 2018;Sadia et al, 2018;Smith et al, 2018) and quantitatively (Fina et al, 2017;Markl et al, 2017;Fina et al, 2018a,b;Gioumouxouzis et al, 2018a;Verstraete et al, 2018). Such assessment can include pore distribution, pore morphology and size, calculation of total porosity, or evaluation of surface and subsurface pores and pore interconnectivity.…”

“…Shape variations due to imperfect printing for example can be quantified by means of nominal (Computer-aided design, CAD) vs. actual (printed object) comparison, where the µCT imaging data of the printed object are co-registered with the CAD data used to for the printing and compared by applying logical operators. An example of such operators is described by Markl et al and presented in Figure 1 (Markl et al, 2017). The workflow allows for the identification of a subvolume within either the µCT which does not overlap with the CAD model (XOR-XµCT data) and vice versa (XOR-CAD data).…”

Progress in Additive Manufacturing of Energetic Materials: Creating the Reactive Microstructures with High Potential of Applications

“…An interesting example of a combination of additive and formative approaches was used to first prepare a 3D-printed aluminum framework and then melt cast the charges with liquid TNT [146]. Most likely, the interrupted 3D printing of the compartment to fill the hollow with a target substance can be applied for some energetic compositions, analogous to the drug industry [253].…”