Tag Archives: Christoph Gerber

Atomic force microscope with nanowire sensors

Measuring the size and direction of forces may become reality with a nanotechnology-enabled atomic force microscope designed by Swiss scientists, according to an Oct. 17, 2016 news item on phys.org,

A new type of atomic force microscope (AFM) uses nanowires as tiny sensors. Unlike standard AFM, the device with a nanowire sensor enables measurements of both the size and direction of forces. Physicists at the University of Basel and at the EPF Lausanne have described these results in the recent issue of Nature Nanotechnology.

A nanowire sensor measures size and direction of forces (Image: University of Basel, Department of Physics)

A nanowire sensor measures size and direction of forces (Image: University of Basel, Department of Physics)

An Oct. 17, 2016 University of Basel press release (also on EurekAlert), which originated the news item, expands on the theme,

Nanowires are extremely tiny filamentary crystals which are built-up molecule by molecule from various materials and which are now being very actively studied by scientists all around the world because of their exceptional properties.

The wires normally have a diameter of 100 nanometers and therefore possess only about one thousandth of a hair thickness. Because of this tiny dimension, they have a very large surface in comparison to their volume. This fact, their small mass and flawless crystal lattice make them very attractive in a variety of nanometer-scale sensing applications, including as sensors of biological and chemical samples, and as pressure or charge sensors.

Measurement of direction and size

The team of Argovia Professor Martino Poggio from the Swiss Nanoscience Institute (SNI) and the Department of Physics at the University of Basel has now demonstrated that nanowires can also be used as force sensors in atomic force microscopes. Based on their special mechanical properties, nanowires vibrate along two perpendicular axes at nearly the same frequency. When they are integrated into an AFM, the researchers can measure changes in the perpendicular vibrations caused by different forces. Essentially, they use the nanowires like tiny mechanical compasses that point out both the direction and size of the surrounding forces.

Image of the two-dimensional force field

The scientists from Basel describe how they imaged a patterned sample surface using a nanowire sensor. Together with colleagues from the EPF Lausanne, who grew the nanowires, they mapped the two-dimensional force field above the sample surface using their nanowire “compass”. As a proof-of-principle, they also mapped out test force fields produced by tiny electrodes.

The most challenging technical aspect of the experiments was the realization of an apparatus that could simultaneously scan a nanowire above a surface and monitor its vibration along two perpendicular directions. With their study, the scientists have demonstrated a new type of AFM that could extend the technique’s numerous applications even further.

AFM – today widely used

The development of AFM 30 years ago was honored with the conferment of the Kavli-Prize [2016 Kavli Prize in Nanoscience] beginning of September this year. Professor Christoph Gerber of the SNI and Department of Physics at the University of Basel is one of the awardees, who has substantially contributed to the wide use of AFM in different fields, including solid-state physics, materials science, biology, and medicine.

The various different types of AFM are most often carried out using cantilevers made from crystalline Si as the mechanical sensor. “Moving to much smaller nanowire sensors may now allow for even further improvements on an already amazingly successful technique”, Martino Poggio comments his approach.

I featured an interview article with Christoph Gerber and Gerd Binnig about their shared Kavli prize and about inventing the AFM in a Sept. 20, 2016 posting.

As for the latest innovation, here’s a link to and a citation for the paper,

Vectorial scanning force microscopy using a nanowire sensor by Nicola Rossi, Floris R. Braakman, Davide Cadeddu, Denis Vasyukov, Gözde Tütüncüoglu, Anna Fontcuberta i Morral, & Martino Poggio. Nature Nanotechnology (2016) doi:10.1038/nnano.2016.189 Published online 17 October 2016

This paper is behind a paywall.

All about Atomic Force Microscopy (AFM) with Gerd Binnig and Christoph Gerber

Gerd Binnig, Christoph Gerber, and Calvin Quate invented the atomic force microscope in the 1980s and an Aug. 16, 2016 news item on Nanotechnology Now announces a discussion with two of the inventors, Binnig and Gerber (Note: Links have been removed),

The inventors of one of the most versatile tools in modern science – the atomic force microscope, or AFM – tell their story in an interview published online this week. The AFM was invented in the mid 1980s by Gerd Binnig, Christoph Gerber and Calvin Quate, three physicists who are sharing the 2016 Kavli Prize in Nanoscience.

Binnig and Gerber discuss their inspiration for the device, how they solved problems through sport, and why their invention continues to propel science at the nanoscale.

This charming Aug. 20, 2016 discussion for the Kavli Foundation focuses on more than the AFM although it is the main topic,

Our roundtable panelists were:

GERD BINNIG –is a physicist and Nobel Laureate for his invention (with Heinrich Rohrer and Christoph Gerber) of the scanning tunneling microscope while at IBM Zurich. He began development of the atomic force microscope in 1986 to overcome the limitations of his previous invention.
CHRISTOPH GERBER –is a physicist and director for scientific communication at the Swiss Nanoscience Institute at the University of Basel. While at IBM, Gerber worked closely with Binnig on bringing both the scanning tunneling microscope and atomic force microscope to fruition.

Calvin Quate was unable to participate in the roundtable. The transcript has been amended and edited by the laureates

THE KAVLI FOUNDATION [TKF]: You filed your first patent for the atomic force microscope (AFM) nearly 30 years ago. How has it changed the way we look at the world since then?

GERD BINNIG: It was like the first time people looked through an optical microscope and saw bacteria. That completely changed how we look at the world. Suddenly, we understood what was really going on in nature, and we used that knowledge to learn how diseases spread. The AFM is the next step. It lets us look at the molecules that make life possible in those bacteria – and everywhere else – and see things we could not see before. It teaches us how to make changes to surfaces or molecules that we attempted blindly in the past. And it has been used in so many different scientific studies, from looking at polymers and chemical reactions to modifying surfaces at the atomic level.

CHRISTOPH GERBER: As Gerd explained, seeing is believing, and now we can do that onthe atomic scale. AFM has turned into the most powerful and most versatile toolkit that we have for doing nanoscience. And it keeps evolving. In just the past few years, researchers have learned to pick up a molecule on the tip of an AFM, which we can think of as the needle on a record player, and reveal chemical bonds while imaging molecules on surfaces. Nobody thought that ever would be possible.

TKF: Has this changed how researchers think about the ways nanoscale interactions affect the things they study?

BINNIG: Very much so. Before AFM, people who wanted to model very small structures –molecules, cell walls, semiconductors – had to make indirect measurements of them. But those structures can be complex and disordered, and indirect measurements do not always capture that, so the models they came up with were often wrong. But now, we can look at those structures and adapt our models to match what we observe. We as scientists always have to connect our theories to reality. Atomic force microscopy lets us do this.

TKF: When you started thinking about the AFM, biology was one of the fields you had inmind. Yet even you must have been surprised at how it has revolutionized biology.

GERBER: Yes. AFM’s capabilities keep evolving, and researchers are always finding new ways to use it. For example, in recent years, researchers have made tremendous progress in taking AFM measurements in real time. It’s like watching a movie. They can now see biological interactions, such as how molecules degrade or how antimicrobials attack bacterial membranes as they occur – something nobody could have foreseen 20 years ago. It took 15 years to get there, but we can now see biology in action and compare that to our theories.

BINNIG: Exactly. In biology, the biggest and most important question is always whether a molecule will bind to another molecule, change it, and by changing it cause something important to happen. This is all about forces, and researchers can use AFM to bring two molecules or even two cells close together, or pull them apart, and measure those forces directly. We can learn how big those forces are and under what conditions they occur. We’re actually looking into the heart of biology when we do that.

GERBER: And atomic force microscopy can tell us about many different types of forces that determine the outcome of chemical reactions at the nanoscale. These range from chemical, mechanical and electrostatic through, most recently, to the very weak interactions between molecules.

BINNIG: A great example of this is how Hermann Gaub, a professor of biophysics at Ludwig Maximilians University of Munich, used AFM to unfold proteins. He actually attached one end of a protein to a surface and the other end to an AFM tip. When he pulled the tip up, the protein straightened out and he could create a fingerprint of the unfolding forces that he could compare with his model.

TKF: What about applications you could not have foreseen?

BINNIG: I could not have foreseen that we can image molecules with such a high resolution. It’s unbelievable. We can see the bonds between molecules. We can watch them change during a chemical reaction, and sometimes there are surprises. Some researchers have observed an intermediate state in a chemical reaction that should not have lasted long enough to see. So they have had to rethink their theories to take into account why this intermediate state lasted so long. That’s what happens when we can observe such high-resolution details.

GERBER: Another example is high-speed AFM, which biologists use to see the cellular machinery in action. No other technique can do that. It works by tapping a very, very thin cantilever up and down, taking one quick measurement after another.

BINNIG: It is amazing how many people use the AFM in so many different fields. We first thought, well, maybe biology or semiconductor research. But it was picked up everywhere, from studying friction to cosmetics.

GERBER: I recently looked it up, and AFM was mentioned in 353,000 peer-reviewed papers. Our original article was published in Physical Review Letters, the top journal in the field in which all the important theoretical work is published. Ours is the only experimental paper on its list of most-cited papers.

TKF: Amazing. And yet AFM was actually a follow-up to another technology you worked on, the scanning tunneling microscope, or STM. It was probably the first instrument to achieve nanoscale resolution without using electrons or other high-energy beams that can damage what you are observing, right?

BINNIG: Yes.

TKF: And where did that idea come from?

BINNIG: We were trying to solve a problem. IBM was working on a new type of semiconductor chip, and the insulator, which keeps the electric current from escaping the semiconductor, was leaking. But no one knew why. So Heinrich Rohrer, who was working at IBM Zurich, hired me. I looked to all the available instruments, and none of them could study materials on such a fine scale to find out.

So the two of us thought, well, okay, we’ll invent something. We thought we could take advantage of something called quantum tunneling. Quantum tunneling is when an electron tunnels through a conducting material and come out the other side. We developed STM to map the surface of the material by measuring where electrons emerged on the other side. Only later did we realize that we could move our probe from one spot to cover the entire surface.

TKF: Dr. Gerber, you quickly became part of the STM team. What convinced you to join?

GERBER: I felt this was such a crazy idea, and I’m always very fond of this sort of thing. I thought this was fantastic.

BINNIG: I can confirm this. Christoph always likes crazy things. That runs through his life.

GERBER: Actually, the development of STM was kind of an undercover project at the beginning, because Gerd and Heinrich were involved in other projects. I worked for a year or so on my own. When we started overcoming problems and we could see features on the surface of a material that were one-tenth of a nanometer, then it really took off.

I leave you to discover the discussion in its entirety: Aug. 20, 2016 discussion.

Nature celebrates some nanotechnology anniversaries

An April 5, 2016 editorial in Nature magazine celebrates some nanotechnology milestones (Note: Links have been removed),

In March 1986, the atomic force microscope (AFM) was introduced by Gerd Binnig, Calvin Quate and Christoph Gerber with a paper in the journal Physical Review Letters titled simply ‘Atomic force microscope’1. This was 5 years (to the month) after the precursor to the AFM, the scanning tunnelling microscope (STM), had first been successfully tested at IBM’s Zurich Research Laboratory by Binnig and the late Heinrich Rohrer, and 7 months before Binnig and Rohrer were awarded a share of the Nobel Prize in Physics for the design of the STM (the prize was shared with Ernst Ruska, the inventor of the electron microscope). Achieving atomic resolution with the AFM proved more difficult than with the STM. It was, for example, only two years after its invention that the STM provided atomic-resolution images of an icon of surface science, the 7 × 7 surface reconstruction of Si(111) (ref. 2), whereas it took 8 years to achieve a similar feat with the AFM3, 4.

The editorial also provides an explanation of how the AFM works,

The AFM works by scanning a sharp tip attached to a flexible cantilever across a sample while measuring the interaction between the tip and the sample surface. The technique can operate in a range of environments, including in liquid and in air, and unlike the STM, it can be used with insulating materials; in their original paper, Binnig and colleagues used the instrument to analyse an aluminium oxide sample.

Then, the editorial touches on DNA (deoxyribonucleic acid) nanotechnology (Note: Links have been removed),

The history of structural DNA nanotechnology can, like the AFM, be traced back to the early 1980s, when Nadrian Seeman suggested that the exquisite base-pairing rules of DNA could be exploited to build artificial self-assembled structures11. But the founding experiment of the field came later. In April 1991, Seeman and Junghuei Chen reported building a cube-like molecular complex from DNA using a combination of branched junctions and single-stranded ‘sticky’ ends12. A range of significant advances soon followed, from 2D DNA arrays to DNA-based nanomechanical devices.

Then, in March 2006, the field of structural DNA nanotechnology experienced another decisive moment: Paul Rothemund reported the development of DNA origami13. This technique involves folding a long single strand of DNA into a predetermined shape with the help of short ‘staple’ strands. Used at first to create 2D structures, which were incidentally characterized using the AFM, the approach was quickly expanded to the building of intricate 3D structures and the organization of other species such as nanoparticles and proteins. …

Happy reading!

R.I.P. Heinrich Rohrer, co-inventor of the scanning tunneling microscope, 1933-2013

Heinrich Rohrer died May 16, 2013 according to the May 22, 2013 news item on Nanowerk,

The co-inventor of the scanning tunneling microscope, Dr. Heinrich Rohrer, passed away on the evening of May 16, 2013. He was 79.

Heinrich Rohrer, IBM Fellow and Nobel Laureate, joined the IBM Research Laboratory in Zurich, Switzerland, in December of 1963, where he worked for 34 years.

After hiring a young scientist named Gerd Binnig in the late 1970s, the two started collaborating, brought closely together by their backgrounds in superconductivity and their fascination with atomic surfaces. The two scientists grew increasingly frustrated by the limits of the tools then available to study the distinct characteristics of atomic surfaces, so they decided to build their own, something that would be capable of seeing and manipulating atoms at the nanoscale level.

The May 2013 obituary on the IBM research website, which originated the news item, commemorates Rohrer’s Nobel winning accomplishment, the co-invention of the scanning tunneling microscope (STM),

Dr. Heinrich Rohrer, IBM Fellow, Nobel Laureate and co-inventor of the scanning tunneling microscope, passed away on the evening of May 16, 2013. He was 79. Dr. Rohrer joined IBM Research – Zurich in December of 1963, where he worked for 34 years.

“The invention of the scanning tunneling microscope was a seminal moment in the history of science and information technology,” said Dr. John E. Kelly III, IBM senior vice president and director of Research. “This invention gave scientists the ability to image, measure and manipulate atoms for the first time, and opened new avenues for information technology that we are still pursuing today.”

After hiring a young scientist named Gerd Binnig in the late 1970s, the two started collaborating, brought together by their backgrounds in superconductivity and their fascination with atomic surfaces. They grew increasingly frustrated by the limits of the tools then available, so they built their own, capable of seeing and manipulating atoms at the nanoscale level.

They began experimenting with tunneling, a quantum phenomenon in which electrons can escape the surface of a solid. When another surface approaches, the electron clouds can overlap and an electric current can flow.

Binnig and Rohrer found that when maneuvering a sharp metal conducting tip over the surface of a sample, the amount of electrical current flowing between the tip and the surface could be measured. Variations in the current provided information about the inner structure, and from this information,  they could build a three-dimensional atomic-scale map of the sample’s surface.

In January 1979, Binnig and Rohrer submitted their first patent disclosure on the scanning tunneling microscope (STM). Soon afterwards, with the help of fellow IBM researcher Christoph Gerber, they began to design and construct the microscope.

In awarding Binnig and Rohrer the Nobel Prize in Physics in 1986, just five years after the first STM had been built, the Nobel committee said the invention opened up “entirely new fields… for the study of the structure of matter.”

In 2011, in the presence of 600 guests from throughout the research community, IBM and ETH Zurich dedicated the Binnig and Rohrer Nanotechnology Center in Rüschlikon in honor of the scientists’ achievements.

“ For me, Heini was father figure, role model, emotional and spiritual teacher, and best friend – all rolled into one. An eminent person, with an incredible sense of humanity and kindness. ”

-Gerd Binnig

Heinrich Rohrer was as famous for his kindly personality as for his sharp wit and humor. During the opening ceremony of the Center he participated in a public discussion with Binnig and Dr. Ralph Eicher, then president of ETH Zurich. After Binnig attempted to explain their invention, Rohrer jokingly apologized to the audience saying, “If you didn’t quite understand what Gerd just told you, you are not alone.”

Here are a few biographical details from the obituary page on the IBM website,

Heinrich Rohrer was born on June 6, 1933, in Buchs, Switzerland. In 1949, the Rohrer family moved to Zurich and a few years later Heinrich enrolled at the Swiss Federal Institute of Technology in Zurich (ETH), where he studied Physics under Wolfgang Pauli.

In the summer of 1961, Heinrich married Rose-Marie Egger and their honeymoon in the United States led to a two-year project studying thermal conductivity of type-II superconductors and metals at Rutgers University. Shortly thereafter in 1963, he returned to Switzerland to join the Physics department at the newly founded IBM Research – Zurich Laboratory.

The rest, as they say, is history.

ETA May 23, 2013: Dexter Johnson wrote a touching tribute in his May 23, 2013 posting, Heinrich Rohrer: The Modest Pioneer of Nanotechnology.