Windows into the Microcosm

How does a young zebra finch learn to sing? And how can electronic circuitry be manufactured on the nanometer scale? Instruments for the latter are being created at Carl Zeiss in the German town of Oberkochen. The production hall there is about 400 meters long, and cost roughly half a billion euros to build. But then you have to think big in order to venture into the smallest worlds. Here at Carl Zeiss, the employees develop and manufacture things that influence our everyday lives and enrich our knowledge.

One example is “correlative microscopy,” which combines two different worlds of imaging and knowledge: those of optical and electron microscopes. With this technology, Christian Thomas of Carl Zeiss was able to support work underway at the Institute of Neuroinformatics in Zurich, which is run jointly by the University of Zurich (UZH) and the Swiss Federal Institute of Technology (ETH).

The researchers there are studying how zebra finches learn to sing. “To achieve this goal, they have to know what connections exist between the ‘song centers’ of the bird’s brain and other regions of the brain,” says Thomas, who holds a doctorate in electrical engineering.

These connections were made visible with optical and electron microscopes, with each type of microscope providing its own specific information. “When these data sets are superimposed electronically,” explains Christian Thomas, “the result is a very detailed picture of the connections.”

To do this, it is important that the images of both types of microscope show exactly the same region — that they are “correlated”, in other words. Markings are therefore burned into the specimen slide with a laser to help achieve this correlation. Each microscope acquires its orientation from these markings and aligns the specimen slide in accordance with them. The L-shaped markings serve as reference points, so that a microscope automatically moves to precisely the region shown in the image from the other microscope.

To that end, the image files contain metadata, which also ensures a means of verification and documentation. This technique makes it possible to gain a great deal of additional knowledge in the life sciences —the zebra finch serves as a model of language acquisition in humans, after all. But it also provides new insights for the materials sciences. One example is the study of the charging and discharging processes in lithium-ion batteries, through which engineers hope to better understand the effects of battery aging and then use this knowledge to make mobile sources of electricity that last longer.