The construction of the primary capsule is a necessary step for the construction of a spherical shape which is coated afterwards. In the following figure is shown an example of a primary capsule:

Figure 1: Primary capsules made of alginate and calcium ions.

In the best-case scenario, the core contains the all the encapsulating material. However, for a good process control, additional compounds are needed. As instance, the use of Ca²⁺-ions is needed for cross-linkage of alginate.

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Figure 2: Different wall sizes due to variation of cross-linking agents and shell material.

In our department, we focus mainly on two factors:

• Firstly, the ideal cross-linking agents, which are influencing different parameters of the shape, like permeability, stability or thickness of the wall.
• Secondly, on additives, which are necessary to adjust the viscosity and supports the building of the outer shell.