Scanning atomic force microscopes, first introduced into commerce in 1989, are a powerful tool for nanoscale science and engineering. Capable of seeing individual atoms, commercial AFM prices range between US$10K and $1M, depending on the unit's features and capabilities. During the recent LEGO2NANO summer school held at Tsinghua University in Beijing, a group of Chinese and English students succeeded in making a Lego-based AFM in five days at a cost less than $500.

LEGO2NANO is the third in a series of China-UK Summer Schools held on the campus of Tsinghua University. Teams of university students from diverse backgrounds spent five days trying to design a sub-$500 atomic force microscope that could be used by Chinese high school students.

An atomic force microscope resolves nanoscale details of surface structure (it can even show individual atoms) by contacting the surface with a very thin probe.

A schematic of the main components of an atomic force microscope on the left, with an AFM image of a deformed copper surface on which chains of atoms are easily seen (Photo: OverlordQ and Rhynnolomous)

Holding the probe against the surface with a constant force, the probe is scanned across the surface. Sensors amplify the vertical movement of the probe as it moves over surface features. The result is a constant force mapping of the sample surface.

The LEGO2NANO teams were challenged to build a functioning scanning atomic force microscope, using only Lego pieces, Arduino microcontrollers, 3D-printed parts and consumer electronics.

The winning team took only five days to design and finish a microscope to the level that it successfully demonstrated all the required functions of the challenge, producing a scanned image of nanoscale detail on a sample surface.

Their microscope is mounted on a metal plate for stability. Housings and compartments were built from Lego and 3D printed parts. The scanning stage was also 3D printed, and was based on a design pioneered at Bristol University. The scanning stage is moved by piezoelectric actuators that, controlled by Arduino processors, move the stage by a micron for an application of 10 volts, meaning that the smallest possible steps (essentially setting the AFM's resolution) are no more than a few nanometers.

The development of the student AFM designs will continue in sessions at the Institute of Making at University College London and at the Open Wisdom Laboratory at Tsinghua University. The designs of the student teams will be made public (following additional refinement), and new engineering teams are challenged to build a fully functional AFM in a year's time for less than $100. This will be a fascinating effort to revisit as progress continues.

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