Biomedical Engineering Reference
In-Depth Information
Table A4. Some commercial sources of nanoparticles for probe shape and
z
axis calibration.
Supplier and link
Particle type
Ted Pella
Gold colloids in 5, 15, or 15 nm diameter
Thermo Scientific
Polystyrene nanospheres in a range from 20 to
900 nm
EvidentTechnology Inc.
Quantum dots in a range from 2.2 to 5.8 nm
Electron Microscopy Sciences
Colloidal gold in 0.8, 6, 10, 15 and 25 nm
diameters
A6 Biomolecules
Often it is necessary to verify SPM image quality on soft samples or samples with weak
adhesion to the surface. It is important that this type of reference has a long-life, is stable
and is indestructible. Before measuring images of 'unknown' biological molecules it is
often helpful to practice on this 'known' sample. Example sources are include in Table A5.
A7 Lateral force microscopy/friction
The most well-known commercial LFM references come as 1-D arrays of triangular steps
having precise linear and angular dimensions [337]. Establishing quantitative LFM data
requires standardizing the AFM scanner output in the vertical and horizontal axis. Some
alternatives are also available; the use of crystals with well-known angles has been
19.6 nm
113.03 nm
0 nm
0.00 nm
0 µm
1.5 µm
0.00 µm
4.95 µm
Fig. A5. Example of colloidal samples suitable for AFM calibration. Left: AFM image of 102 nm
diameter polymer nanoparticles. Right: image of 15 nm gold nanoparticles. Software can be used for
counting the particles and for measuring the size distribution of the particles.
