Using laser beams to paint in 3D

The growth of 3D printing has resulted in a whole slew of novel capabilities. It is now possible to grow your own lab equipment, to reproduce your own robots and to print your own pharmaceuticals. However, what if what you wish to create requires greater precision than 3D printing can provide?

In answer to this question, researchers at the Technische Universität Wein (TU Wien) have developed a new technique named 3D-photografting, details of which are included in a recent issue of the journal Advanced Functional Materials. The technique uses hydrogel – a material constructed from macromolecules arranged in a loose meshwork. The composition of this material allows the scientists to direct molecules or cells to specific locations before employing a laser beam to lock them into position. Practical applications for 3D-photografting might include the enhanced capacity to create micro-sensors and even the ability to grow biological tissue.

I spoke to Dr Aleksandr Ovsianikov from the University’s Institute of Materials Science and Technology to learn more about how 3D-photografting was developed and the ways in which the technique might be utilised.

"Our group at TU Wien is concerned with developing Additive Manufacturing Technologies (AMTs) based on light-induced polymerisation," he began. "One of these techniques, known as two-photon polymerisation (2PP), employs multi-photon absorption of femtosecond laser radiation to induce a photopolymerisation reaction. In most cases it can be said that liquid monomer solutions are locally converted into a solid within the light-material interaction volume. By scanning the focal point of a laser beam with the material volume, 3D structures can be built. This enables us to produce structures with very high spatial resolutions, but from the same material."

As Dr Ovsianikov went on to explain, 3D-photografting is a continuation of 2PP.

"3D-photografting is similar to 2PP as it uses identical equipment," he continued. "However, the chemistry involved is different. Rather than ‘building up’ the structure, it allows immobilisation of molecules onto a polymeric matrix in a spatially defined manner. Immobilising molecules in this manner enables us – in three dimensions – to change the ‘chemical’ properties of a matrix locally, and with a high degree of precision."

Interdisciplinary collaboration between researchers at TU Wien's Institutes of Materials Science and Technology, and Applied Synthetic Chemistry, played a vital role in the development of 3D-photografting. "Our work was made possible by complementing competences within the fields of mechanical engineering, chemistry and laser-induced material processing," explained Dr Ovsianikov.

The flexibility of the tool, which essentially allows scientists to tune a material’s chemical properties with micrometer precision, is one of its main advantages. However, it also makes it difficult to predict what the 3D-photografting will be used for in the future.

"We have developed a universal method that is compatible with many polymeric matrices and molecular compounds used for functionalisation," Dr Ovsianikov concluded. "It is therefore hard to anticipate every possible application. However, bioengineering, lab-on-a-chip technologies and general sensing techniques would all be sensible bets."


For further information, take a look at this review in which Dr Ovsianikov and his colleagues discuss multiphoton processing technologies for biological and tissue engineering applications.