Taking electron microscopy to the next level
A new technique is said to be the only one capable of exploring materials in the range of one picometre
German researchers Haider, Rose and Urban share the 'Frontiers of Knowledge Award' for inventing the subatomic precision microscope, which opens up new developments in the nanoscience field.
When others had given up on the goal of achieving subatomic precision, the three formed a team, secured funding and, within a decade, had solved the problem and designed a working prototype.
The image obtained through aberration-corrected transmission electron microscopy makes it possible to observe in detail the behaviours of atoms and correlate them with the physical properties of materials.
Several hundred of these microscopes are now in use around the world in materials, nanoelectronic and molecular biology research.
The sixth annual BBVA Foundation Frontiers of Knowledge Award in the Basic Sciences category went to German physicists Maximilian Haider, Harald Rose and Knut Urban for "greatly enhancing the resolving power of electron microscopy by developing aberration-corrected electron optics, a breakthrough enabling subatomic precision."
The three researchers took on an obstacle challenge - the low resolution of electron microscopy - that was barring the way to progress in nanotechnology and was also viewed as largely insurmountable. In fact, state agencies decided to suspend official funding of the field, just as the new laureates were joining forces to find a solution. In less than a decade, they not only had a theoretical solution but also a prototype microscope.
Their technique is said to be the only one capable of exploring materials in the range of one picometre, equal to one hundredth of the diameter of a hydrogen atom - a trillionth of a metre. This enables the motions of each atom and its interactions to be imaged with a hitherto undreamt-of precision.
The nomination was put forward by Achim Bachem, Chairman of the Board of Research Centre Julich and Vice President of the Helmholtz Association of German National Research Centres. In his view, the laureates' contribution "arrives at a time where the developing nanosciences, in particular physics and chemistry as well as the related nanotechnologies, are calling for high-resolution instrumentation for research, synthesis and validation of technologies."
Imaging atoms to predict properties
Haider, Rose and Urban's microscope fulfils one of physicists' most cherished ambitions: to determine, from the imaging of atoms, which behaviour corresponds to a particular property, like conductivity or hardness.
And then by emulating this behaviour, to achieve the property in question. This, in turn, will facilitate the design of custom-made materials, opening up multiple new applications in electronics and biomedicine.
In the words of the jury's citation, aberration-corrected transmission electron microscopy - the name of Haider, Rose and Urban's technique - "in now a key technique in many areas of fundamental and applied science," enabling scientists to "study the consequences of subtle atomic shifts in the properties of materials, and dynamics of interactions at specific atomic sites."
It is now being used in the study of materials like graphene, in new chip miniaturisation techniques and in molecular biology, among other fields. Proof of its importance is the speed with which it has been taken up by the scientific community.
Haider, Rose and Urban secured the funding for their work in 1991 and had a prototype going by 1997. In 1998, they published the first captured images in Nature, and in 2001 unveiled the technique at a scientific meeting in San Francisco.
As early as 2003, the first commercial microscopes had reached the lab, and now there are hundreds deployed around the world - two of them in Spain - despite a price that can run to four million dollars.
The jury stressed how sheer tenacity had got the three men to their goal: "A little over two decades ago, the resolution of the electron microscope used to explore materials (...) appeared to have reached its limits, and, having given up hope, the community's attention shifted elsewhere. The persistence of Maximilian Haider, Harald Rose and Knut Urban over the next decade led to the understanding, development and deployment of aberration-corrected techniques in electron optics."
They also explain in their citation how the three worked together as a team. Rose came up with a novel optical concept that solved the underlying problem, derived from the image distortion caused by lenses - a phenomenon known as spherical aberration; Haider constructed the prototype of an aberration-corrected transmission electron microscope; and Urban developed this prototype into a working platform for the physics of materials.
"A real shock"
The three laureates declared themselves both grateful and surprised when they learned about the award. "I am so happy. I really didn't think we were going to win it," remarks Haider. "It's a really nice feeling," adds Urban.
Haider, the founder of a company that commercialises aberration-corrected transmission electron microscopes, stressed that understanding the atomic structure of materials is the first step to improving them, so we can create, for instance, "memory chips for mobile phones."
He also explains the advantages of his technique over tunnelling microscopy, which can also image materials at the atomic level, albeit with lower resolution.
Haider says, "Tunnelling microscopy allows you to see the atoms in a sample, but only on the surface. We, however, can also have a look through the object. We can see the positions of atoms and observe and measure them with a precision of around 50 picometres. This means we can observe how materials interact on the atomic scale, and deduce their macroscopic properties from their microscopic characteristics."
The new electron microscopes are also useful in biology, to examine viruses for example. And they win out over conventional electron microscopes in being less aggressive with the biological samples.
Asked why they decided to persevere where many of their colleagues had given up, both Haider and Urban say they were convinced at the time that the problem could be cracked. The three scientists based at different institutions and exploring different directions within materials science, coincided at a conference in 1989 where Rose presented his theoretical approach. "Within five minutes I had an idea for a solution, but it took me another twenty years to catch up with these five minutes," Rose recalls.
"And the idea was a good one," remarks colleague Urban, himself by that time a reputed scientist. The three decided to collaborate and apply for a public grant, unaware that U.S. agencies had just decided to call off the search for a higher-resolution electron microscope. But Rose, who admits to a stubborn streak, was convinced that the goal could be achieved, in that "there was no physical law to prevent it." Determined to press on in the face of rejection, Haider, Rose and Urban approached the Volkswagen Foundation, which, as Urban explains, funds research "that is not necessarily all that close to practical developments."
Urban admits that this was a risky career move, given the dimensions of the challenge; "But if you don't take risks, you don't discover new things!" And he points out the paradox that a project that struggled to find funding "has produced industrial results extremely fast."
Adamant that it is the science only that interests him, his name does not figure on many of the patents protecting the technique, though he is "totally on board" with basic research leading to industrial developments. "When I began working with Rose and Haider, all the equipment purchased by my laboratory came from Japan. European manufacturers had abandoned the sector, because there were no new products, no innovation."