It's a Bumpy Ride for Nanocars in Air

Subjecting nanocars to ambient conditions offers insights into producing molecular machines

2 min read
Molecules that alight on a surface used to test nanocars look more like obstacles, according to researchers at Rice University and North Carolina State University testing the mobility of single-molecule cars in open air.
Molecules that alight on a surface used to test nanocars look more like obstacles, according to researchers at Rice University and North Carolina State University testing the mobility of single-molecule cars in open air.
Illustration: Rice University and North Carolina State University

So-called “nanocars” have been a fixture on the nanotechnology landscape for at least the last decade.  And, no, these will not be cars that we humans will be shrunk down to fit into like in the sixties sci-fi movie “Fantastic Voyage.”  Instead nanocars are molecular-scale devices that can be directed to move around with light or other means and ferry around payloads not unlike the way a macroscale vehicle might.

Now researchers at Rice University, who developed the first nanocars, have teamed up with researchers at North Carolina State University to make it possible for nanocars to move around in ambient environments instead of being restricted to vacuums.

“Our long-term goal is to make nanomachines that operate in ambient environments,” said James Tour of Rice University in a press release. “That’s when they will show potential to become useful tools for medicine and bottom-up manufacturing.”

In research described in the Journal of Physical Chemistry C, progress towards nanocars that can move about outside of a vacuum starts with adamantine wheels that are water repellent (hydrophobic).

Hydrophobicity is key to keeping the nanocars connected to the surface because it minimizes the amount of surface area that comes in contact with the wet surface. If the wheels are attracted to water, they could be swept away in the flow of water. Balance is the key. If the wheels are made too hydrophobic they could be stuck in place.

When it comes to nanocars, the roads they travel on are usually made of glass, or glass coated with the polymer polyethylene glycol (PEG). In the research, a plain glass surface was coated with hydrogen peroxide so the wheels wouldn’t stick and the PEG-coated glass offered a non-sticky surface without any further treatment.

So, it was off to the races. This time the nanocars would be moving on the glass surface exposed to open air rather than in a vacuum. The results were not aimed at achieving the fastest lap times, but to determine the kinetics of nanocar movement and the interaction between the car and the surface over time.

“We want to know what makes a nanocar ‘hit the brakes’ and how much external energy we need to apply to start it moving again,” said Tour in the release.

It was a tough day out on the track. The nanocars, which are really nothing more than molecules made up of a few hundred atoms, had a hard time moving on the glass surfaces that continued to get “dirtier” being exposed to the molecules in the air.  Each one of the molecules acted like a huge obstacle that made it impossible for the nanocars to continue moving.

All the nanocars moved faster on the PEG-coated slides and twice as many nanocars moved on these slides than did on the glass only slides.

While it may have been a tough day for the nanocars, the results are not expected to impact their chances at the upcoming first ever Nanocars Race in France this autumn. The video below offers a little insight into the competition.

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3 Ways 3D Chip Tech Is Upending Computing

AMD, Graphcore, and Intel show why the industry’s leading edge is going vertical

8 min read
A stack of 3 images.  One of a chip, another is a group of chips and a single grey chip.
Intel; Graphcore; AMD

A crop of high-performance processors is showing that the new direction for continuing Moore’s Law is all about up. Each generation of processor needs to perform better than the last, and, at its most basic, that means integrating more logic onto the silicon. But there are two problems: One is that our ability to shrink transistors and the logic and memory blocks they make up is slowing down. The other is that chips have reached their size limits. Photolithography tools can pattern only an area of about 850 square millimeters, which is about the size of a top-of-the-line Nvidia GPU.

For a few years now, developers of systems-on-chips have begun to break up their ever-larger designs into smaller chiplets and link them together inside the same package to effectively increase the silicon area, among other advantages. In CPUs, these links have mostly been so-called 2.5D, where the chiplets are set beside each other and connected using short, dense interconnects. Momentum for this type of integration will likely only grow now that most of the major manufacturers have agreed on a 2.5D chiplet-to-chiplet communications standard.

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