Microscopic copper structures produced with ETH Zurich’s new 3D microprinting process

January 24, 2016

Scientists at Switzerland’s ETH Zurich have developed a new method of 3D microprinting that allows the direct manufacture of tiny, complex metal components in a single step. The new technique is a refinement of the FluidFM system developed at ETH Zurich several years ago, where a moveable micropipette mounted on a leaf spring can be positioned extremely precisely.

ETH-micro-prin-t-1

ETH researchers use a movable micropipette

(blue) to manufacture tiny copper objects.

(Visualisation: ETH Zurich / Alain Reiser)

As part of his doctoral thesis at ETH Zurich, Luca Hirt of the Laboratory of Biosensors and Bioelectronics has been investigating the possibility of using FluidFM for printing processes.

In the new method a droplet of liquid is placed on a base plate made of gold. The tip of the micropipette penetrates the droplet and acts as a print head. A copper sulphate solution flows slowly and steadily through the pipette and using an electrode, the scientists apply a voltage between the droplet and the substrate, causing a chemical reaction under the pipette aperture. The copper sulphate emerging from the pipette reacts to form solid copper, which is deposited on the base plate as a tiny 3D pixel.

Using a computer to control the movement of the micropipette, the researchers can print three-dimensional objects pixel by pixel and layer by layer. The spatial resolution of this process depends on the size of the pipette’s aperture, which in turn determines the size of the copper deposits.

At present, the scientists can produce individual 3D pixels with diameters ranging from 800 nanometres to more than five micrometres, and can combine these to form larger 3D objects. In an initial feasibility study, various spectacular microscopic objects were created. They consist of pure, non-porous copper and are mechanically stable, as studies by scientists from the group led by Ralph Spolenak, Professor of Nanometallurgy at ETH Zurich, showed.

“This method can be used to print not only copper but also other metals,” stated Tomaso Zambelli, Associate Lecturer and Group Leader at the Laboratory of Biosensors and Bioelectronics at ETH Zurich. “FluidFM may even be suitable for 3D printing with polymers and composite materials,” added Zambelli.

A further advantage of the new method over other 3D microprinting processes is that the forces acting on the tip of the pipette can be measured via the deflection of the leaf spring on which the micropipette is mounted. “We can use this signal as feedback. Unlike other 3D printing systems, ours can detect which areas of the object have already been printed,” stated Hirt. “This will make it easier to automate the printing process.”

The ETH spin-off Cytosurge has now licensed the method from ETH Zurich. Pascal Behr played a key role in developing FluidFM at ETH several years ago and today is CEO of Cytosurge. “We see big market potential in the printing process and an opportunity to further diversify our company,” stated Behr. “We are convinced of the idea of using FluidFM in 3D microprinting. Now, the task is to optimise this application in collaboration with interested researchers at universities and in industry – for example, in the watchmaking, medical technology and automotive sectors.” Behr sees an initial application in the field of rapid prototyping, where microscopic components can be manufactured quickly and easily using 3D printing.

ETH-micro-print

The objects shown in these microscope images have a width of 15 to 35 micrometres.

In comparison, a human hair is approximately 50 micrometres wide. (All photos: ETH Zurich / Luca Hirt)

 

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