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Drivers gear up for world’s first nanocar race

Chemists will navigate molecular wagons along a tiny golden track.

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Hubert Raguet/CEMES/CNRS Photothèque

Molecules as seen through a scanning tunnelling microscope at the Centre for Materials Elaboration and Structural Studies in Toulouse. The same instrument will be used to drive molecules in the world’s first nanocar race.

Six teams from three continents are preparing for a unique race on a polished gold track in the south of France this month. But this is no luxurious supercar event: competitors will be racing single molecules. In 36 hours, they aim to move them a distance of 100 nanometres — about one-thousandth the width of a human hair — on a laboratory track held in a vacuum and chilled to a few degrees above absolute zero.

The contest is being billed as the world’s first nanocar race, and the aim is to get people excited about nanotechnology and molecular machines, says co-organizer Christian Joachim, a chemist who works at the Centre for Materials Elaboration and Structural Studies in Toulouse, where the event will take place. He and Gwénaël Rapenne, a chemist at the University of Toulouse-Paul Sabatier, developed the contest after Joachim realized — following an interview with a journalist — that nanocars attracted much more public attention than did his research on fundamental aspects of nanotechnology.

The ‘Windmill’ nanocar travels over a surface: filmed during training at Dresden.

The race may also provide scientific insights for the contestants, who want to learn more about how their individual molecules interact with surfaces. That may help in the design of catalysts and, in the longer term, further the aim of creating molecular-scale technologies for transporting cargo or information, participants say. “It’s a gigantic experiment, performed by many people at the same time,” Joachim says. (Nature Nanotechnology, which is independent of Nature’s news team, is a sponsor of the race.)

Driving with electrons

The term nanocar is actually a misnomer, because the molecules involved in this race have no motors. (Future races may incorporate them, Joachim says.) And it is not clear whether the molecules will even roll along like wagons: a few designs might, but many lack axles and wheels. Drivers will use electrons from the tip of a scanning tunnelling microscope (STM) to help jolt their molecules along, typically by just 0.3 nano-metres each time — making 100 nanometres “a pretty long distance”, notes physicist Leonhard Grill of the University of Graz, Austria, who co-leads a US–Austrian team in the race.

Contestants are not allowed to directly push on their molecules with the STM tip. Some teams have designed their molecules so that the incoming electrons raise their energy states, causing vibrations or changes to molecular structures that jolt the racers along. Others expect electrostatic repulsion from the electrons to be the main driving force. Waka Nakanishi, an organic chemist at the National Institute for Materials Science in Tsukuba, Japan, has designed a nanocar with two sets of ‘flaps’ that are intended to flutter like butterfly wings when the molecule is energized by the STM tip (see ‘Molecular race’). Part of the reason for entering the race, she says, was to gain access to the Toulouse lab’s state-of-the-art STM to better understand the molecule’s behaviour.

Eric Masson, a chemist at Ohio University in Athens, hopes to find out whether the ‘wheels’ (pumpkin-shaped groups of atoms) of his team’s car will roll on the surface or simply slide. “We want to better understand the nature of the interaction between the molecule and the surface,” says Masson.

Adapted from www.nanocar-race.cnrs.fr

Simply watching the race progress is half the battle. After each attempted jolt, teams will take three minutes to scan their race track with the STM, and after each hour they will produce a short animation that will immediately be posted online. That way, says Joachim, everyone will be able to see the race streamed almost live.

Nanoscale races

Chemists have previously created tiny nanocars with wheels and axles — as well as molecular rotors and switches. The 2016 Nobel Prize in Chemistry, awarded to creators of nanomachines, has renewed interest in the field. However, the Nobel prizewinners worked mainly with large numbers of molecules in solution, Joachim says, whereas the researchers in this race are focusing on the interactions between single molecules and solid surfaces.

But cars on the nanoscale behave nothing like their real-life counterparts, making it hard to find uses for the machines. At these scales, electrostatic forces dominate and random thermal vibrations constantly shake molecules around. Consequently, nano-machines may end up behaving in un-expected or unpredictable ways, Grill says.

The Toulouse laboratory has an unusual STM with four scanning tips — most have only one — that will allow four teams to race at the same time, each on a different section of the gold surface. Six teams will compete this week to qualify for one of the four spots; the final race will begin on 28 April at 11 a.m. local time. The competitors will face many obstacles during the contest. Individual molecules in the race will often be lost or get stuck, and the trickiest part may be to negotiate the two turns in the track, Joachim says. He thinks the racers may require multiple restarts to cover the distance.

Journal name:
Nature
Volume:
544,
Pages:
278–279
Date published:
()
DOI:
doi:10.1038/544278a

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  1. Avatar for Pentcho Valev
    Pentcho Valev
    "Contestants are not allowed to directly push on their molecules with the STM tip. Some teams have designed their molecules so that the incoming electrons raise their energy states, causing vibrations or changes to molecular structures that jolt the racers along. Others expect electrostatic repulsion from the electrons to be the main driving force." Not pushed by the tip of the hose but by the water jet? Not very interesting in either case I am afraid. There must be asymmetrical molecular structures able to move in a certain direction without being pushed by the experimentalist - they will be violating the second law of thermodynamics and are immeasurably more interesting. Similarly, time crystals regularly jolted by the experimentalist are not interesting at all and yet they are being hyped. In contrast, time crystals "jolted" by ambient heat and breathtakingly violating the second law of thermodynamics are never discussed: https://www.youtube.com/watch?v=17UD1goTFhQ "The Formation of the Floating Water Bridge including electric breakdowns" http://ebooks.adelaide.edu.au/o/orwell/george/o79n/chapter2.9.html "Crimestop means the faculty of stopping short, as though by instinct, at the threshold of any dangerous thought. It includes the power of not grasping analogies, of failing to perceive logical errors, of misunderstanding the simplest arguments if they are inimical to Ingsoc, and of being bored or repelled by any train of thought which is capable of leading in a heretical direction. Crimestop, in short, means protective stupidity." Pentcho Valev
  2. Avatar for Pentcho Valev
    Pentcho Valev
    Contestants should be forbidden to push or pull the device in any way, and then only interesting devices will remain, like this one (if it is not secretly pushed or pulled): https://m.youtube.com/watch?v=0niaH-ybAdc Weird walking gel Pentcho Valev
  3. Avatar for Pentcho Valev
    Pentcho Valev
    There is no push or pull in the walking gel case - temperature changes cause the effect: https://www.newscientist.com/article/dn28025-watch-a-shape-shifting-gel-take-its-first-steps/ Watch a shape-shifting gel take its first steps Since there are temperature changes the violation of the second law of thermodynamics is not evident, but such devices always have isothermally working analogues: "pH sensitive or pH responsive polymers are materials which will respond to the changes in the pH of the surrounding medium by varying their dimensions. Such materials increase its size (swell) or collapse depending on the pH of their environment." https://en.wikipedia.org/wiki/PH-sensitive_polymers The work-producing cycle is easy to imagine. The experimentalist adds hydrogen ions to the system - the polymer swells or contracts and does work in the process - e.g. lifts a weight, or makes its first walking step. The experimentalist removes the same amount of hydrogen ions from the system - the polymer resumes its initial state (makes its second walking step) and a new cycle can begin: http://upload.wikimedia.org/wikipedia/commons/f/f6/PH_sensitive_polymer_swelling-collapse_mechanism.jpg http://www.gsjournal.net/old/valev/val3.gif http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1367611/pdf/biophysj00645-0017.pdf A. KATCHALSKY, POLYELECTROLYTES AND THEIR BIOLOGICAL INTERACTIONS, p. 15, Figure 4: "Polyacid gel in sodium hydroxide solution: expanded. Polyacid gel in acid solution: contracted; weight is lifted." http://www.google.com/patents/US5520672 "When the pH is lowered (that is, on raising the chemical potential, μ, of the protons present) at the isothermal condition of 37°C, these matrices can exert forces, f, sufficient to lift weights that are a thousand times their dry weight." The second law of thermodynamics is violated unless the experimentalist, in adding hydrogen ions to the system and then removing them, does (wastes) more work than the work gained as the polymer lifts the weight. However electrochemists know that, if both adding and removing are performed reversibly, the net work involved is zero (the experimentalist gains work if the hydrogen ions are transported from a high to a low concentration but then loses the same amount of work in the backward transport). Pentcho Valev
  4. Avatar for Pentcho Valev
    Pentcho Valev
    Devices violating the second law of thermodynamics are commonplace - there are countless hints in that direction in the literature. Sometimes a description consisting of one sentence is enough - no need to read the original paper. See this for instance: http://ieeexplore.ieee.org/document/4399392/?reload=true "For example, more than ten years ago, an electrically-driven polymer gel actuator controlled by the on-off switching of the electric field could make a forward move with worm-like motion [3]." I have no idea which paper is referenced by [3] but am sure that the polymer is a perpetual motion machine of the second kind - the on-off switching provides no energy for the walking gel so the ambient heat remains the only energy source. Pentcho Valev
  5. Avatar for Pentcho Valev
    Pentcho Valev
    Here is the referenced paper: https://www.nature.com/nature/journal/v355/n6357/pdf/355242a0.pdf "A SYSTEM capable of converting chemical energy to mechanical energy could serve as an actuator or an 'artificial muscle' in several applications. Here we describe a chemomechanical system of this sort based on a synthetic polymer gel. The gel network is anionic, and positively charged surfactant molecules can therefore bind to its surface, inducing local shrinkage by decreasing the difference in osmotic pressure between the gel interior and the solution outside. By using an electric field to direct surfactant binding selectively to one side of the gel, we can induce contraction and curvature of a strip of gel. Reversing the direction of the field causes contraction of the opposite side, and when the gel is suspended in solution from a ratchet mechanism, it can thereby be made to move with a worm-like motion at a velocity of up to 25 cm min^(-1)." Yes, a perpetuum mobile of the second kind par excellence. Instead of "walking", the device could cyclically lift weights. And it is not true that CHEMICAL energy is converted into mechanical energy. The only energy source is the ambient heat, but if used for "walking", the absorbed heat returns to the surroundings in the end and its role remains somewhat hidden. If, however, the device lifted weights, then it would be obvious that the energy stored in the lifted weights could only be transformed ambient heat. Pentcho Valev
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