Improved Atomic Force Microscope Uses Nanowire Sensors

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Atomic Force Microscopes
dominika zarzycka | Shutterstock.com

Conventional Atomic Force Microscopes utilize laser beams, and therefore require special preparations.

New research shows that using nanowires instead of laser beams would not only make such microscopes more efficient, but also much more sensitive.

What’s an AFM?

An Atomic Force Microscope, or AFM, allows scientists to conduct research and make observations on the infinitely tiny nanoscale. The invention is credited to Christoph Gerber, among other contributors, who developed the original just over 30 years ago.

Currently, most AFMs are based in the laser beam deflection method using a reflective lever or cantilever. This lever connects to a position-sensitive sensor to map the nano surface. Forces then act on the sensor to produce both a map of the object and an image of its surface.

Therefore, using a laser beam requires special surface preparation.

However, researchers have found that using nanowires instead of the laser beam eliminates the need for special surface preparation, thus expediting the process.  Furthermore, properties and structures specific to nanowires make them inherently good sensors.

limited space and resolution Are The main drawbacks of using current laser beam deflection AFMs.

Nanowires as Sensors

Using Nanowires instead of laser beams, physicists at the University of Basel and the EPF Lausanne have developed a new AFM capable of measuring the size and direction of nanoscale forces.

With a diameter of 100 nanometers, nanowires offer a lot of surface area compared to their volume. The increase in surface area contributes to the sensitivity of the nanowires, and therefore, the AFM as a whole.

The nanowires also have low mass and are made of materials that form a perfect crystal lattice.

Nanowires are also capable of vibrating along two axes at nearly the same frequency due to their particular mechanical forces. The changes in perpendicular vibrations from encountering different forces can be used to detect forces acting on the nanoscale.

The main drawback with the current laser beam deflection AFMs is the limitation of space and resolution due to diffraction limit and aberration. Nanowire-based AFMs, in contrast, measure the vibrations in nanowires as they encounter different forces. They are, therefore, easier to deploy and measure the size and direction of forces.

AFMs using nanowires are, therefore, easier to deploy and also more effectively measure the size and direction of acting forces.

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