Additive manufacturing of porous biominerals

Abstract

Soft bodies of small creatures are frequently protected with hard shells whereas those of larger creatures are often supported with hard load-bearing structures. Nature usually fabricates these hard functional materials from soft organic scaffolds that are mineralized. To enable an energy-efficient locomotion of these creatures while maintaining the functionality of their protective or load-bearing components, nature minimizes the weight of these materials by making them porous. Unfortunately, methods that offer a similar degree of control over the nanometer up to the centimeter length scale structure of synthetic minerals remain elusive. Here we present a process that combines direct ink writing with emulsion templating to 3D print strong biominerals possessing pores whose diameters range from the 100s of nm up to the mm length scale at ambient temperature. After the structures have been stabilized through a second mineralization step, our samples encompass up to 80 wt% of CaCO3 and display a density and compressive strength close to those of human trabecular bones.