Polydimethylsiloxane (PDMS), also known as silicone rubber, has several useful properties, and there has been a lot of interest lately in 3D printing the material. However, it’s a difficult process, as you generally need to heat the material rapidly or use special chemistry to cure it. But according to a team of researchers from Penn State, 3D printing technology can be used to improve the strength and cell adhesion of PDMS polymer.

 

While the material is most commonly used in geometrically simple flexible baking pans and heat-resistant silicone spatulas, which can be easily molded, it can also help make biological machines, two- and three-dimensional cell culture platforms, organ-on-a-chip devices, and lab-on-a-chip devices, which require smaller, more complex geometries.

 

Ibrahim Ozbolat [Image: Penn State]

“So far, PDMS (polydimethylsiloxane, or silicone) has limitations in formability and manufacturing of devices. Most research is done using casting or micro molding, but this fabrication yields materials with weak mechanical properties and also weak cell adhesion,” explained  Ibrahim T. Ozbolat, Hartz Family Associate Professor of Engineering Science and Mechanics and bioengineering at Penn State. “Researchers often use extracellular proteins like fibronectin to make cells adhere.”

Any material that’s used as 3D printer “ink” has to be able to go through the print nozzle and maintain its shape after it’s been deposited onto the print bed – design integrity is gone if the material flattens, seeps, or spreads out. But the researchers discovered that by combining two different polymer forms – PDMS elastomers Sylgard 184 and SE 1700 – they could 3D print silicone parts with complex geometries that had improved biological adhesion and mechanical characteristics without having to resort to molding, casting, and spin coating to make only simple forms.