JPK Instruments NanoWizard
®
Handbook Version 2.2a
19
adhesive layer is required for storage, since the chips are held in the wafer. Gelpacks
can be bought from cantilever manufacturers or can be home made for storing tips
after delivery Instructions for making gel-packs are given later in this document (see
Section 0
The cantilever and tip are both susceptible to damage
If the tip is damaged, the tip radius generally increases. With worn or contaminated
tips, the image resolution will be lower and the images may have serious artifacts (see
the discussion in
Section 7
). Damage to the cantilever arm may also cause problems
for imaging.
Handle the cantilever chips carefully:
•
Do not touch the cantilevers with fingers. Use tweezers to handle them.
•
Do not drop the cantilever chips. The cantilevers may break off the chip.
•
Only open the cantilever package when necessary.
•
Only open the cantilever package in a clean environment.
•
The tips may also be damaged through inappropriate scanning conditions:
•
Too high gain parameters may lead to a damage of the cantilever tip.
•
Too high setpoint values in contact mode may damage the tip.
•
Too low setpoint values in intermittent contact mode may damage the tip.
4.3 Cantilever types for different imaging modes
The geometry and the material of the cantilever both contribute to the properties that
make a cantilever suitable for any particular imaging modes. Most cantilevers are
designed for either contact or intermittent contact mode. The shape/geometry of the
cantilevers influences the properties that qualify the cantilever to be a contact or an
intermittent contact one. The chip and the tip do not have any influence on this,
however.
Contact mode
For contact mode, AFM cantilevers with low spring constants are required. As tip wear
is inevitable in contact mode, any additional tip coating will be subject to damage. Use
silicon nitride tips or diamond coatings if a reliable tip shape is required. Silicon nitride
tips will deliver best results for soft materials.
•
Low force constant
•
“Soft cantilevers”
•
Low resonant frequency
•
Longer and thinner
Using cantilevers that are too stiff (such as most of the cantilevers designed for
intermittent contact mode) can lead to applying high forces to the sample. On hard
samples, the tip can then be damaged very easily. On soft samples the tip can
damage the sample easily. There are some cantilevers that are strongly
not
advised
for use in contact mode. Cantilevers with especially sharp tips such as EBD
cantilevers (see below) and sharply edged cantilevers are so delicate that their very
easily be damaged if used in contact mode.
