The scanning atomic force microscope, capable of resolution on the order of fractions of a nanometer, is 1000 times more sensitive than that of the optical diffraction limit.
The original scanning tunneling microscope, a stop on the way to scanning atomic force microscopy, was built based on work by Ernst Ruska, Gerd Binnig and Heinrich Rohrer at IBM Research in Zurich. Their work earned them the Nobel Prize for Physics in 1986.
One of the prime tools used to image, measure, and manipulate matter at the nanoscale, the AFM gathers information by "feeling" the surface of an object via a mechanical probe. Piezoelectric elements are used to direct miniscule and acutely accurate movements to scan surfaces. Advanced versions of the instruments use tiny currents which pass through a cantilevered tip to probe the electrical conductivity or transport of an underlying surface.
When they were first introduced into commercial markets back in 1989, AFM's were rather pricy, ranging from $10,000 all the way up to $1,000,0000, according to which features and capabilities a machine might include.
But now, during the LEGO2NANO project at Tsinghua University in Beijing, a group of Chinese and English students made a Lego-based AFM in five days – and at a cost of less than $500.
Yep, you read that right, the students created a microscope capable of imaging a single atom.
LEGO2NANO, the third in a series of China-UK Summer Schools held at Tsinghua University, put teams to work designing a version of the atomic force microscope which will ultimately be used by Chinese high school students in their investigations.
By holding a probe against the surface of an object with a constant force, the probe moves across an object's surface while sensors amplify the vertical movement of the probe to create a constant force mapping.
Using nothing more than Lego pieces, Arduino microcontrollers, a series of 3D printed parts and consumer electronics, the students hit the mark with the winning team taking just five days to finish a microscope capable of producing a scanned image – in nanoscale detail – on a sample surface.
Mounted on a metal plate for stability, the AFM features housings and compartments built from Lego blocks and 3D printed parts. The student's ARM scanning stage was 3D printed and based on a design created by researchers at Bristol University. Moved by piezoelectric actuators controlled by Arduino processors, the stage moves one micron for each 10 volts applied. These tiny movements give the ARM a resolution of little more than a few nanometers.
And the work started at LEGO2NANO isn't done quite yet.
The Institute of Making at UCL and the Open Wisdom Laboratory at Tsinghua University plan to continue to host student sessions aimed at developing the concept. Next target: building a fully-functioning AFM for $100.