Cells are known to have an active participation in shaping their environment. It has been shown that there is a two-way communication between the cells and the scaffold/extra-cellular matrix. However, most of the approaches have been towards manipulation of cells via either chemical modification of surfaces or static 3D patterns. The aim of this project is to design and fabricate structures which can be actively deformed by traction forces applied by cells.

In the current work, a scaffold design inspired from snake-skin Kirigami based meta-material has been showcased. A snake-skin is flexible, yet it protects the creature on multiple harsh terrains. Similarly, the scaffold is made of tiles that provide surface area, and thin joints connecting the tiles that provide flexibility to the whole structure. The whole structure is 3D printed of the same material. The structures are printed with the help of two-photon-polymerization based printing. This technique uses a near-infrared laser to achieve photopolymerization and can produce feature sizes as small as 100 nm. This allows us to fabricate structures in the size range of what can be perceived as truly 3D environments for cells. The auxetic design not only decreases the force needed for deformation in contrast to bulk material but also notably surpasses the conventional 'beams-and-columns' scaffold design in this aspect. Mechanical characterization of Kirigami pattern at macro-scale (mm range) shows 80-90% drop in stiffness compared to the bulk material. Such low structural stiffness allows us to use wide range of materials since the mechanical properties can be modulated by changing design parameters rather than material chemistry. Preliminary cell studies show the scaffold is structurally soft enough to have visible deformation after cells have attached to the structure.

Study of cell-scaffold interction in such a system will give us an insight into how cells behave in a 3D auxetic environment and the kind of forces cells exert in an individual as well as collective form on their surrounding.