Nanowires as Scanning Force Sensors

Nanowires are extremely tiny filamentary crystals which are built-up molecule by molecule from various materials and which are now being very actively studied by scientists all around the world because of their exceptional properties. The wires normally have a diameter of around 100 nanometers. Because of this tiny dimension, they have a very large surface in comparison to their volume. This fact, their small mass and flawless crystal lattice make them very attractive in a variety of nanometer-scale sensing applications, including as sensors of biological and chemical samples, and as pressure or charge sensors.

In 2017, researchers in the Poggio Lab demonstrated that nanowires can also be used as force sensors in atomic force microscopes. Based on their special mechanical properties, nanowires vibrate along two perpendicular axes at nearly the same frequency. When they are integrated into an AFM, the researchers can measure changes in the perpendicular vibrations caused by different forces. Essentially, they use the nanowires like tiny mechanical compasses that point out both the direction and size of the surrounding forces.

In Rossi et al., the scientists from Basel describe how they imaged a patterned sample surface using a nanowire sensor. Together with colleagues from the EPF Lausanne, who grew the nanowires, they mapped the two-dimensional force field above the sample surface using their nanowire “compass”. As a proof-of-principle, they also mapped out test force fields produced by tiny electrodes.

 

 

Gallery

  • Bike Tour 2018

    On Friday, May 11th, 2018, the group went on a day-long bicycle tour of nearby Alsace, France.

  • Davide, Martino, and the Probe

    Prof. Poggio and Ph.D. student Davide Cadeddu are shown here with our custom-made 3He scanning probe microscope.

  • Nanowires as Scanning Force Sensors

    A new type of atomic force microscope (AFM) uses nanowires as tiny sensors. Unlike standard AFM, the device with a nanowire sensor enables measurements of both the size and direction of forces.

  • SNI Video 2014

    In December 2014, the group was featured in a Swiss Nanoscience Institute (SNI) video on the Masters and Ph.D. school on nanoscience here at the University of Basel. (Video)

  • Scanning nanowire microscope

    A photo of our new custom-built low-tempearture high-vacuum scanning nanowire microscope.