Micro-scale pillars formed — or photostructured — in the OSTE polymer using UV light. Photo: KTH Royal Institute of Technology.
Micro-scale pillars formed — or photostructured — in the OSTE polymer using UV light. Photo: KTH Royal Institute of Technology.

Researchers at KTH Royal Institute of Technology in Sweden have developed a new polymer suited for photostructuring — a technique for creating micro-scale shapes. The discovery opens new possibilities for medical diagnostics, biophotonics and 3D printing.

The so-called off-stoichiometry thiol-enes (OSTE) polymer was developed by the KTH researchers specifically to meet the need for a material that is suitable for both experimental prototyping and large-scale manufacturing of the miniaturized bioanalytical laboratories known as labs-on-a-chip.

"It can be very useful in a variety of applications such as near-patient diagnostic tools," says one of the developers, Tommy Haraldsson, a docent in the Department of Micro and Nanosystems at KTH.

One of the unique qualities of the OSTE polymer is that its surface is chemically reactive without adding anything or preparing the surface in any way, but now the researchers have uncovered another benefit. In a paper in Microsystems and Nanoengineering, they report the discovery that upon exposure to ultraviolet (UV) light the molecules of the polymer arrange themselves in a manner that significantly enhances photostructuring.

Photostructuring is a technique that uses UV light to solidify micro-scale 3D shapes in a liquid polymer. "These microstructures can guide light, such as with waveguides. Or they can be used to control fluid flow, such as with microfluidics channels," says Gaspard Pardon, a post-doc researcher in the Department of Micro and Nanosystems.

The KTH researchers have been developing the OSTE polymer over the past five years to bridge the ‘lab-to-fab-gap’, and create an alternative to suboptimal off-the-shelf materials that are now used for conceptual lab-on-a-chip device development. The predominant materials used today are known to have poor mechanical or chemical properties, such as absorption of small molecules and difficulties with permanent surface modification.

With the KTH material, however, it is possible to easily add different layers of material or to modify the surface properties for handling microscopic flows of fluids, without using glue or otherwise treating the material surface. Another advantage is that the material allows simple changes to the surface's wettability and chemistry.

Up to now, the major class of polymers to which the KTH material belongs, thiol-ene copolymers, has been considered to be inappropriate for photostructuring. "With this new understanding of the underlying mechanisms and material properties available, we can also anticipate future exciting applications," Pardon says. "Biophotonics is one such area."

Biophotonics harnesses light and other forms of radiant energy to understand the inner workings of cells and tissues. This approach allows researchers to see, measure, analyze and manipulate biological materials in ways never before possible.

"We also started testing the 3D printing of our new material," Pardon adds. "By producing 3D structures that have the material's special surface chemical properties, it would allow the polymer to be used in a variety of new applications. We can also integrate sensitive biomaterials and bioreagents, and the manufacturing cost is potentially reduced because the material is so easy to work with."

This story is adapted from material from the KTH Royal Institute of Technology, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.