Laser tuning a 3D lab on a chip

August 29, 2012 // By Nick Flaherty
Researchers in Vienna have devised a way to position molecules in a 3D substrate that provides more flexible and accurate sensors for a 'lab on a chip'.

Two research teams from the Vienna University of Technology collaborated closely to develop the 3D 'photografting' method. Both research groups have been developing new kinds of 3D-printers but for the current applications, 3D-printing would not have been useful. “Putting together a material from tiny building blocks with different chemical properties would be extremely complicated,” said Dr Aleksandr Ovsianikov in the University's Institute of Materials Science and Technology. “That is why we start from a three dimensional scaffold and then attach the desired molecules at exactly the right positions.”

The process starts with a hydrogel with large pores through which other molecules or even cells can migrate. Specially selected molecules are introduced into the hydrogel meshwork, then certain points are irradiated with a laser beam. At the positions where the focused laser beam is most intense, a photochemical bond is broken, creating highly reactive intermediates which locally attach to the hydrogel very quickly. The precision depends on the laser’s lens system, at the Vienna University of Technology a resolution of 4µm could be obtained.

“Much like an artist, placing colors at certain points of the canvas, we can place molecules in the hydrogel – but in three dimensions and with high precision”, said Ovsianikov.

Depending on the application, different molecules can be used. 3D photografting is not only useful for bio-engineering but also for other fields, such as photovoltaics or sensor technology. In a very small space, molecules can be positioned which attach to specific chemical substances and allow their detection, making a 3D “lab on a chip” possible.