Assessing an object's consistency without touching it

Jun 25, 2012
Close up of the Pyrex sphere and Pyrex plane on which the nanometric scale elastic film is deposited. The small drop of liquid that serves as a probe is visible.© Richard Villey and Frédéric Restagno

( -- Two teams of researchers have succeeded in evaluating the rigidity of a material … without touching it! To achieve this feat, physicists from the Laboratoire de Physique de la Matière Condensée et des Nanostructures (CNRS / Université Claude Bernard Lyon 1) and the Laboratoire de Physique des Solides (Université Paris-Sud / CNRS) placed a liquid–where they created a very weak, nanometric scale flow–between the probed object and the “tester”.

This technique, derived from the latest advances in nano-mechanics, has the advantage of being non-invasive and therefore non-destructive and could significantly improve the testing and analysis of thin, fragile objects such as bubbles or cells. This work is published on-line on June 18, 2012 on the website of the journal Physical Review Letters.

A simple way of determining whether a body is hard or soft is to touch it with a harder object. The problem with this technique is that it can destroy the item, especially if it is extremely fragile like a bubble or a living cell. Developing a less invasive alternative was therefore vital. To assess the rigidity of an object without touching it, the team of physicists had envisaged blowing on it delicately to check whether this flow of air deformed the material or not. But precisely controlling a flow of air is difficult on account of the vortexes that can form in the air. Hence the idea of using an easier-to-control “nano-flow” of fluid instead.

Enlarged view of the device.© Richard Villey et Frédéric Restagno

The researchers tested their technique on a thin elastomer (rubber) film, only several hundreds of nanometers (1) thick. In concrete terms, they placed the film on a rigid glass support and immersed the lot in a mixture of water and glycerol. They then created a very slight displacement of the liquid, near to the film. To generate this nano-flow, the physicists, and more particularly Samuel Leroy who was then working on his PhD at LPMCN (2), had to use a special device, developed in 2000 in the same laboratory (3). It comprises in particular a millimetric Pyrex (special glass) sphere, attached to a rod, which can be finely moved with what is known as a “piezoelectric ceramic” system. It is precisely this tiny glass bead that allows a nano-flow to be created at the surface of an object.

When the sphere comes up very close to the material (0.000001 meters), it pushes the liquid towards the object. This nano-flow generates a very slight pressure on the surface of the material. This force deforms the film very slightly, if it is flexible. On the other hand, if the tested object is completely rigid, the film remains unchanged.

The two teams also discovered that their method can be used to measure the rigidity of an array of bubbles, an element so fragile that touching it would mean destroying it! It is the first time that the possibility of measuring the elastic properties of an object using a nano-flow of fluid has been demonstrated. This initial work opens the way to a new nanometric-scale imaging technique for observing the elastic properties of very thin or thicker objects.

Explore further: Team invents microscopic sonic screwdriver

More information: Hydrodynamic interaction between a spherical particle and an elastic surface: A gentle probe for soft thin films. Samuel Leroy, Audrey Steinberger, Cécile Cottin-Bizonne, Frédéric Restagno, Liliane Léger and Elisabeth Charlaix. Physical Review Letters. 18 June 2012

Related Stories

How to Rip a Fluid

Jun 01, 2007

In a simple experiment on a mixture of water, surfactant (soap), and an organic salt, two researchers working in the Pritchard Laboratories at Penn State have shown that a rigid object like a knife passes ...

New 'superlens' reveals hidden nanostructures

Sep 14, 2006

A microscope used to scan nanostructures can be dramatically enhanced by using a 'superlens,' reports an international team of scientists from the Max Planck Institute (MPI) for Biochemistry and The University of Texas at ...

Physicists develop nano-level sound detector

Jan 12, 2012

( -- For a couple of decades now, physicists have known that if a very small laser beam is pointed at a microscopic particle, it could be held in place due to the very small electrical field that ...

Mathematicians model heat flow in human tears

Jun 05, 2012

Mathematicians from the University of Delaware have created a new model of the fluid dynamics and heat flow in human tears. When people blink their eyes, a thin liquid film is spread across the surface of the eye.

Nano-tuned solar cells

May 18, 2011

Solar cells that are more effective and cost less in production: Within the EU-project N2P (Nano to Product) researchers developed nano tuned surfaces to gain both.

First images of flowing nano ripples

Mar 21, 2006

Delft University of Technology (Holland) researchers have shed new light on the formation of nanoscale surface features, such as nano ripples. These features are important because they could be useful as templates ...

Recommended for you

Researchers prove magnetism can control heat, sound

May 28, 2015

Phonons—the elemental particles that transmit both heat and sound—have magnetic properties, according to a landmark study supported by Ohio Supercomputer Center (OSC) services and recently published by ...

How researchers listen for gravitational waves

May 28, 2015

A century ago, Albert Einstein postulated the existence of gravitational waves in his General Theory of Relativity. But until now, these distortions of space-time have remained stubbornly hidden from direct ...

What's fair?: New theory on income inequality

May 27, 2015

The increasing inequality in income and wealth in recent years, together with excessive pay packages of CEOs in the U.S. and abroad, is of growing concern, especially to policy makers. Income inequality was ...

Scientists one step closer to mimicking gamma-ray bursts

May 27, 2015

Using ever more energetic lasers, Lawrence Livermore researchers have produced a record high number of electron-positron pairs, opening exciting opportunities to study extreme astrophysical processes, such ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Jun 25, 2012
Reminds me of an old Stan Freeburg routine:

"Don't a-Polka on-a my bubble machine":)

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.