Block Diagram of SPM-M Kit. In the experiment discussed below, the actual AFM configuration consisted of an XYZ probe nanopositioner without a nanopositioner supporting the sample.
Mad City Labs manufactures high-resolution AFM instruments
consisting of nanopositioning systems and the MadPLL® controller
that can be used with a variety of resonant probes such as a tuning fork with an etched Tungsten tip
or an Akiyama probe
. As an example, see the SPM-M kit
The AFM probe tip is positioned in proximity to the sample surface using the Z-axis of a nanopositioner. The distance between the probe tip and the sample surface is directly related to the magnitude of the force between the tip and sample. The piezo nanopositioner is moved to maintain constant force between the tip and the surface. In a typical experiment, the tip is scanned along the X and Y axes. In this experiment, the Z-axis position is measured directly to provide a height measurement of the sample.
Mad City Labs piezo nanopositioners include integrated, direct measurement position sensors with PicoQ® sensor technology
, already calibrated using NIST-traceable interferometric methods. Any displacement of the moving portion of the piezo nanopositioner will yield a change in position sensor output, with the resolution ultimately limited by the noise of the nanopositioning system. Total AFM noise must be sufficiently low in order to externally measure sub-nanometer motion. Measuring the output of the nanopositioner's absolute position sensors assures accurate scan size and Z-axis position of the probe as it scans over the surface.