Tag Archives: Don Eigler

Controlling the tiniest particles with sound-induced electrical fields

I find the use of sound as a research tool in this June 23, 2021 news item on ScienceDaily to be fascinating,

Engineers at Duke University [North Carolina, USL] have devised a system for manipulating particles approaching the miniscule 2.5 nanometer diameter of DNA using sound-induced electric fields. Dubbed “acoustoelectronic nanotweezers,” the approach provides a label-free, dynamically controllable method of moving and trapping nanoparticles over a large area. The technology holds promise for applications in the fields ranging from condensed matter physics to biomedicine.

A June 22, 2021 Duke University news release (also on EurekAlert) by Ben Kingery, which originated the news item, explains the interest in precise control and the use of sound in more detail,

Precisely controlling nanoparticles is a crucial ability for many emerging technologies. For example, separating exosomes and other tiny biological molecules from blood could lead to new types of diagnostic tests for the early detection of tumors and neurodegenerative diseases. Placing engineered nanoparticles in a specific pattern before fixing them in place can help create new types of materials with highly tunable properties.

For more than a decade, Tony Jun Huang, the William Bevan Distinguished Professor of Mechanical Engineering and Materials Science at Duke, has pursued acoustic tweezer systems that use sound waves to manipulate particles. However, it becomes difficult to push things around with sound when their profile drops below that of some of the smallest viruses.

“Although we’re still fundamentally using sound, our acoustoelectronic nanotweezers use a very different mechanism than these previous technologies,” said Joseph Rufo, a graduate student working in Huang’s laboratory. “Now we’re not only exploiting acoustic waves, but electric fields with the properties of acoustic waves.”

Instead of using sound waves to directly move the nanoparticles, Huang, Rufo and Peiran Zhang, a postdoc in Huang’s laboratory, use sound waves to create electric fields that provide the push. The new acoustoelectronic tweezer approach works by placing a piezoelectric substrate–a thin material that creates electricity in response to mechanical stress–beneath a small chamber filled with liquid. Four transducers are aligned on the chamber’s sides, which send sound waves into the piezoelectric substrate.

These sound waves bounce around and interact with one another to create a stable pattern. And because the sound waves are creating stresses within the piezoelectric substrate, they also create electrical fields. These couple with the acoustic waves in a way that creates electric field patterns within the chamber above.

“The vibrations of the sound waves also make the electric field dynamically alternate between positive and negative charges,” said Zhang. “This alternating electric field polarizes the nanoparticles in liquid, which serves as a handle to manipulate them.”

The result is a mechanism that mixes some of the strengths of other nanoparticle manipulators. Because the acoustoelectronic nanotweezers induce an electromagnetic response in the nanomaterials, the nanoparticles do not need to be conductive on their own or tagged with any sort of modifier. And because the patterns are created with sound waves, their positions and properties can be quickly and easily modified to create a variety of options.

In the prototype, the researchers show nanoparticles placed into striped and checkerboard patterns. They even push individual particles around in an arbitrary manner dynamically, spelling out letters such as D, U, K and E [emphasis mine]. The researchers then demonstrate that these aligned nano-patterns can be transferred onto dry films using delicate nanoparticles such as carbon nanotubes, 3.5-nanometer proteins and 1.4-nanometer dextran often used in biomedical research. And they show that all of this can be accomplished on a working area that is tens to hundreds of times larger than current state-of-the-art nanotweezing technologies [emphasis mine].

Nanotweezing technologies? This concept is new to me.How will I work it into my next conversation?

As for spelling out D, U, K, and E, that brings to mind Don Eigler (from his Wikipedia entry),

In 1989, Eigler was the first to use a scanning tunneling microscope tip to arrange individual atoms on a surface, famously spelling out the letters “IBM” with 35 xenon atoms.

Perhaps the Duke University researchers intended an ‘hommage’? or ‘tip of the hat’?

Here’s a link to and a citation for the paper,

Acoustoelectronic nanotweezers enable dynamic and large-scale control of nanomaterials by Peiran Zhang, Joseph Rufo, Chuyi Chen, Jianping Xia, Zhenhua Tian, Liying Zhang, Nanjing Hao, Zhanwei Zhong, Yuyang Gu, Krishnendu Chakrabarty & Tony Jun Huang. Nature Communications volume 12, Article number: 3844 (2021) DOI: https://doi.org/10.1038/s41467-021-24101-z Published 22 June 2021

This paper is open access.

20 bromine atoms, a Swiss cross and room temperature

I haven’t featured a teeny, tiny object in quite a while so here’s a Swiss cross composed of 20 bromine atoms,

20 bromine atoms positioned on a sodium chloride surface using the tip of an atomic force microscope at room temperature, creating a Swiss cross with the size of 5.6nm. The structure is stable at room temperature and was achieved by exchanging chlorine with bromine atoms. (Fig: Department of Physics, University of Basel)

20 bromine atoms positioned on a sodium chloride surface using the tip of an atomic force microscope at room temperature, creating a Swiss cross with the size of 5.6nm. The structure is stable at room temperature and was achieved by exchanging chlorine with bromine atoms. (Fig: Department of Physics, University of Basel)

A July 15, 2014 news item on ScienceDaily features the research illustrated by the image,

The manipulation of atoms has reached a new level: Together with teams from Finland and Japan, physicists from the University of Basel were able to place 20 single atoms on a fully insulated surface at room temperature to form the smallest “Swiss cross,” thus taking a big step towards next generation atomic-scale storage devices. …

A July 15, 2014 Universität Basel press release (also on EurekAlert), which originated the news item, explains why this is a breakthrough,

Ever since the 1990s, physicists have been able to directly control surface structures by moving and positioning single atoms to certain atomic sites. A number of atomic manipulations have previously been demonstrated both on conducting or semi-conducting surfaces mainly under very low temperatures. However, the fabrication of artificial structures on an insulator at room temperature is still a long-standing challenge and previous attempts were uncontrollable and did not deliver the desired results.

In this study, an international team of researchers around Shigeki Kawai and Ernst Meyer from the Department of Physics at the University of Basel presents the first successful systematic atomic manipulation on an insulating surface at room temperatures. Using the tip of an atomic force microscope, they placed single bromine atoms on a sodium chloride surface to construct the shape of the Swiss cross. The tiny cross is made of 20 bromine atoms and was created by exchanging chlorine with bromine atoms. It measures only 5.6 nanometers square and represents the largest number of atomic manipulations ever achieved at room temperature.

Together with theoretical calculations the scientists were able to identify the novel manipulation mechanisms to fabricate unique structures at the atomic scale. The study thus shows how systematic atomic manipulation at room temperature is now possible and represents an important step towards the fabrication of a new generation of electromechanical systems, advanced atomic-scale data storage devices and logic circuits.

Here’s a link to and citation for the paper,

Atom manipulation on an insulating surface at room temperature by Shigeki Kawai, Adam S. Foster, Filippo Federici Canova, Hiroshi Onodera, Shin-ichi Kitamura, & Ernst Meyer. Nature Communications 5, Article number: 4403 doi:10.1038/ncomms5403 Published 15 July 2014

This article is behind a paywall but a free preview is available via ReadCube Access.

The bromine/Swiss cross accomplishment brings to mind Donald M. Eigler and Erhard K. Schweizer of IBM and their spelling of the company name with single xenon atoms in 1989. Here’s what Malcolm W. Browne had to say about it in his April 5, 1990 New York Times article,

Hiram Maxim, the inventor of the machine gun, used to demonstrate his marksmanship by firing patterns of bullets into walls to spell out the initials of potential customers. In a similar vein, I.B.M. announced yesterday that its scientists had spelled out the company’s initials by dragging single atoms into the desired pattern on the surface of a crystal of nickel.

One result of I.B.M.’s tour de force was the cover photograph of the British journal Nature today. In a letter published by the journal, Dr. Donald M. Eigler and Dr. Erhard K. Schweizer of the I.B.M. Almaden Research Center at San Jose, Calif., reported that using an instrument that can discern individual atoms, they had positioned single atoms of xenon into various patterns, including the letters I.B.M.

Browne offers a good description of how a scanning tunneling microscope and the process of moving atoms one atom at a time in the rest of his article.

Nanotechnology and the European Economy; Nokia and IBM’s augmented reality meetings; Don Eigler hypes nanotechnology; physical/virtual/augmented reality meetings with IBM and Nokia

In keeping with my belief that the developments I’m observing are threads in a complex conversation (as per yesterday’s [Oct.20.09] posting), I’m back to highlighting various news items that hint at possible trends.

The European Commission’s Directorate-General for Research has published a call for proposals to study the economic impact of nanotechnology and nanosciences. You can get more details here on Azonano or view the call here.

There’s an interview with Don Eigler, the IBM scientist who’s known for moving Xenon atoms individually so they spell out IBM, in New Scientist here. Interestingly, Mr. Eigler does not have any concerns with regard to health fears related to nanotechnology. He’s aware of toxicology issues but he thinks that if we get it right, there’ll be very few problems, if any.

Following on my ‘nature of reality’ kick, this item about IBM and Nokia developing software that allows virtual reality/augmented reality meetings in physical space caught my attention.From the news item on Physorg.com

With support from IBM Research and Nokia Research Center, the VTT Technical Research Centre of Finland created an experimental system that enables people in multiple locations to interact and collaborate with avatars and objects in a single, virtual meeting . Objects and avatars are located in a “virtual” space that mirrors the corresponding physical room.

There is a video included with the story and it looked like the meeting was taking place in three spaces, two of them were physical and one was virtual. One office (physical) had two people who were interacting with virtual objects while simultaneously meeting in a virtual meeting room with their avatars and the same virtual objects they’d been interacting with in the physical space. A third person (in a geographically removed physical office) joined them in the virtual meeting. Do take a look.

The questions that spring to my mind are these: are all the spaces real? Is one space more real than the others and why? Some might argue that the virtual space is less real because it isn’t physical but then neither are your emotions. Also in the postings here about perception and quantum realities (Oct. 16, 19, and 20, 2009), I noted that our perceptions of reality at the macro level do not coincide with the realities of the quantum world which occasions this questions, What is the nature of reality?