A new process for designing microtechnology in three dimensions has been developed at the University of Twente.
“A three-dimensional micro-world offers huge benefits”, says Antoine Legrain, the doctoral degree candidate who spawned the idea. “Besides electronics, we can also miniaturize three-dimensional mechanical objects from the macro-world.”
The existing electronics in computers and smartphones is mostly two-dimensional and built on one very thin layer. In a 3D micro-electronics world, more transistors could be packed into an enclosure, allowing more memory or faster processors.
Legrain’s work was inspired by Origami, the Japanese art of folding, applied at the micro level. He deals with structures that have a diameter equal to one grain of salt.
Although microtechnology has radically impacted our lives, with applications from the accelerometer in smartphones to the sensors in car airbags, colossal strides can still be made in microtechnology.
Current applications are limited to the two-dimensional. Everything is positioned on a thin layer of glass or silicon, for the production of the semiconductor chips, for example, in smartphones.
The technique outlined by Legrain in his doctoral thesis could form the basis for a new three-dimensional production technique, one which avoids the constraints of the current two-dimensional microtechnology.
One elegant way to create three-dimensional structures is by folding.
The highest embodiment of folding technique is Origami, the Japanese art of folding. In his doctoral thesis Legrain shows that Origami can be applied at all kinds of levels, from solar panels and robots to microtechnology Origami with a diameter of 200 microns (0.2 millimetres).
“Of course, we cannot fold at the micro scale with our fingers, and tricks are required,” says Legrain. “I use the surface tension of liquids to fold microstructures. We do this by evaporating small droplets of water. The droplets are applied to flexible structures, which consequently fold up. If we design it properly, the structure remains folded after the evaporation because the parts remain stuck together. And then you’ve created a 3D structure.”
Barriers to Mass Production
The easiest method for applying small droplets is with a syringe, according to Legrain.
“This method is less suitable for mass production, however. Therefore, we examined whether it is possible to force the droplet through a small channel on the reverse of the structure to be folded. This was successful, although the large-scale folding of thousands of structures at the same time is still a long way off. When folding three-dimensional structures we must avoid folding them totally flat. This can easily be achieved by carefully choosing the order of folding, or by using special touches.”
“Folded mechanical structures are interesting, but have a limited application. We have therefore examined whether we can make electrical connections to the movable parts. That is possible if the connections are well designed. For mass production, it is essential that thousands of structures can be folded at the same time. By immersing a container with thousands of ribbons in water and then letting it dry, it was possible to fold them in one go. We believe that it is possible to fold more complex structures in the same manner, but this still requires detailed follow-up research. The prospects are promising, however.”
For More information:
A. Legrain, T. G. Janson, J. W. Berenschot, L. Abelmann, and N. R. Tas
“Controllable elastocapillary folding of three-dimensional micro-objects by through-wafer filling.”
Journal of Applied Physics. 01/2014; 115(21):214905-214905-9. DOI: 10.1063/1.4878460
Top Photo by Sheila Sund