Rheological Behavior and Printability Study of Tri-Calcium Phosphate Ceramic Inks for Direct Ink Writing Method

Abstract

In the biomedical industry, tricalcium phosphate is a bioceramic substance that is frequently employed in the fabrication of scaffolds and bone structures. Fabrication of porous ceramic structures using conventional manufacturing techniques is very challenging because of the brittle nature of the ceramics, which has led to a newly adapted direct ink writing additive manufacturing method. This work investigates the rheology and extrudability of TCP inks to produce near-net-shape structures. Viscosity and extrudability tests found that stable TCP: Pluronic ink of 50 vol.% was more reliable compared to other tested inks prepared from a functional polymer group polyvinyl alcohol. A line study was carried out to identify the printing parameters suitable for printing structures from the selected ink with lesser dimensional error. Printing speed 5 mm/s and extrusion pressure 3 bar was found suitable to print a scaffold through a nozzle of 0.6 mm, keeping the stand-off distance equal to the nozzle diameter. The printed scaffold was further investigated for its physical and morphological structure of the green body. A suitable drying behavior was studied to remove the green body without cracking and wrapping before the sintering of the scaffold.

Optimizing rheological properties for printability: low-temperature extrusion 3D printing of hydroxyapatite-polycaprolactone mixture inks for bone tissue engineering

“…Notably, these variables Frontiers in Materials frontiersin.org influence the ink's viscosity and flow behavior during the printing process and not only influence the printability but also affect the scaffold stability and shape fidelity as well as the mechanical properties of the resulting 3D printed scaffolds. Despite the recognition of the importance of these variables (Gillispie et al, 2020;Naghieh and Chen, 2021;Tarassoli et al, 2021), few studies have attempted to experimentally establish how these ink variables could influence the printability (M' Barki et al, 2017;Paul D L et al, 2023). Printability has been defined as "the capability to form and maintain reproducible 3D scaffolds from ink using the bioprinting technique" (Naghieh and Chen, 2021).…”

“…A recent study investigated the properties of ceramic inks made from tri-calcium phosphate (TCP):Pluronic surfactant for extrusionbased printing [direct ink writing (DIW)]. The study analyzed the viscosity, shear rate, and viscoelastic behavior of the inks, examined the impact of TCP concentration, dispersant content, and binder type on ink rheology, and concluded that the rheological properties of the TCP inks dictate successful printing of high-quality, consistent filaments (Paul D L et al, 2023). A similar approach was proposed by M'Barki and co-authors, which explored the time-dependent gelation and rheological behaviors required for successful direct ink writing (DIW) of dense and strong ceramic objects using boehmite (a crystalline form of aluminum oxide) gels as ink (M' Barki et al, 2017).…”