Paper Number
AC10 

Session
Additive Manufacturing and Composites

Title
2-functionalities-in-1 : Embedded 3D printing of alginate into a SiO2-CaCl2 gel bath

Presentation Date and Time
October 12, 2022 (Wednesday) 2:30

Track / Room
Track 7 / Ontario

Authors (Click on name to view author profile)

  1. Müller, Florence J. (ETH Zurich, Materials)
  2. Ambra, Zaccarelli (ETH, Materials)
  3. Windlin, Laura (ETH Zurich, Materials)
  4. Vermant, Jan (ETH Zürich, Materials)

Author and Affiliation Lines (in printed abstract book)
Florence J. Müller, Zaccarelli Ambra, Laura Windlin and Jan Vermant
Materials, ETH Zürich, Zürich, Switzerland

Speaker / Presenter 
Müller, Florence J.

Keywords
additive manufacturing; biomaterials; gels

Text of Abstract
Extrusion 3D printing of soft materials is often limited in terms of shape, structure, size, and orientation due to printability constraints. One way to increase printability and shape fidelity is the use of a support bath, which will hold the extruded material in place until it reaches its final state of solidification. Here, we propose a 2-in-1 embedded printing approach, where the support bath gives stability to the printed structure and serves as a crosslinking agent at the same time. The approach is to print an alginate solution into an aqueous colloidal gel of Ludox SiO2 particles and CaCl2. The colloidal gel first serves as a support structure to the liquid alginate, while the CaCl2 ions in the gel crosslink the alginate. Due to a very quick crosslinking of the outer layer of the alginate and outer mechanical support, it is possible to print more elaborate and even overhanging structures. This work first identifies the operating windows of this printing process in terms of material and system properties, using dimensional analysis. In terms of material properties, the primary parameter that can be tuned, are the mechanical properties of the support bath, by changing the SiO2 and the CaCl2 concentration – this also impacts the gelation time which impacts system properties such as the extrusion rate and printing velocity. In a second step, the optimized parameters are applied to fabricate various freeform architectures.