Rahul Karyappa, Akihiro Ohnoa, Michinao Hashimoto
Materials with controlled porosity have found diverse applications in separation, catalysis, energy storage, sensors and actuators, tissue engineering and drug delivery. Multiple methods have been developed to fabricate well-defined porous materials with the pore sizes ranging from nanometers to millimeters. For example, the introduction of sacrificial templates can impart porosity to the materials encapsulating them after the removal of embedded materials. Alternatively, procedures involving phase separation, direct templating and chemical reaction have demonstrated fabrication of hierarchical porous structures. These methods inherently require multiple steps, and are limited in the attainable complexity of the fabricated structures.

Concept of ip3DP – A polymer solution is printed by a DIW 3D printer in a nonsolvent. The printed object is solidified via immersion precipitation, and porosity is imparted to the printed object.
You can find more details at https://www.sutd.edu.sg/Research/Research-News/2019/7/researchers-developed-unique-method-ip3DP