Flexible and porous silicone rubber structures can now be 3-D printed thanks to a new technique that uses the principles behind the formation of sandcastles from wet sand.
The method combines water with solid and liquid forms of silicone to create a pasty ink that can be fed through a 3-D printer. The finding could have biomedical applications and uses in soft robotics.
Corresponding author OrlinVelev and his colleagues from the North Carolina State University in the US, showed that, in a water medium, liquid silicone rubber can be used to form bridges between tiny silicone rubber beads to link them together –similar to how a small amount of water can shape sand particles into sandcastles.
Interestingly, the technique can be used in a dry or a wet environment, suggesting that it has the potential to be used in live tissue –like an ultraflexible mesh encapsulating a healing droplet, or a soft bandage that can be applied or even directly printed on some portion of the human body, for example.
“There is great interest in 3-D printing of silicone rubber, or PDMS, which has a number of useful properties,” said Velev, INVISTA Professor of Chemical and Biomolecular Engineering at NC State. The challenge is, Velev added, that the material generally needs to be rapidly heated or applied with special chemistry to cure it, which can be technically complex.
Velev said their method utilises an extremely simple extrudable material that can be placed in a 3-D printer to directly prototype porous, flexible structures – even under water.“And it is all accomplished with a multiphasic system of just two materials – no special chemistry or expensive machinery is necessary. The ‘trick’ is that both the beads and the liquid that binds them are silicone, and thus make a very cohesive, stretchable and bendable material after shaping and curing,” he added.