Grad students build nanometer-resolution atomic force microscope using Lego and 3D printing
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.
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.
Source: University College London
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The "$10k to $1M" price of commercial instruments to which this is being compared goes mostly to software and calibration equipment which are not present in this version. The original precursor of a commercial AFM in the laboratory of Professor Hansma (UC Santa Barbara) was similarly built from simple parts (no 3D printer needed). Mechanical stability was provided by a rubber tire and patio cement block.
Where are images acquired with the student built SPMs? No image implies the result was so bad it did not even meet the quality of an optical microscope.
The images of copper atoms did not come from a device capable of only many nanometers resolution since 10 copper atoms is 1 nanometer and the resolution to resolve the the copper atom is at least ten times smaller then a nanometer.
Grad students have been building fully functional SPMs for decades for less then $500. SPMs that can actually resolve angstroms not as the piece says "a few nanometers". All such SPM systems rely on "Tips" that are typically atomically sharp and cost as little as $40. So the coming $100 Student built system Dodson writes about will have $60 worth of materials, circuitry and computer interface?
I expected more from Dodson (who claims to be a physicist) then talking about a few nanometers as if such was reasonable resolution for a SPM. most can resolve tenths of an angstrom or .01 nanometer.
A single chip system is possible and in the works and unlike the poor accounting done in this article INCLUDES the $40 tip necessary and core to the technology. Such a device has the properties and capability of resolution at the atomic scale.
The copper atom image shown was acquired in a relatively short time since thermal drift dominates such images resolving 0.01 nanometer. In the same time the system must have many resolved points in order to be the basis for a faithful rendering. Such performance is not done with arduinos, a bright and creative person may be able to substantially reduce the costs for an SPM but after bright people trying just that for almost 30 years such costs turn out to be a small part of the SPM costs that matter. A subject matter beyond this piece and deserving of treatment in a multi-page article.
Beyond the resolution issue the images shown come from a PC not an arduino. So the PC (or iPad) cost is at least $300.
Finally the speed of scan, number of scan points and resolution of the force or z axis change is critical to assessing whether one has just built a demo for the basic idea of a SPM or a real and useful microscope.
Sadly the article does not even mention the latter parameters generally let alone what was achieved.