5. Probing the Tomato Cuticle Surface with Atomic Force Microscopy (Digital Instruments Nanoscope IIIa; procedures will vary slightly among microscopes)6
Turn on the scanning probe microscope (SPM) (Fig. 2) and make sure that the microscope mode toggle switch is set to the contact Atomic Force Microscopy (AFM) mode.
Manually raise the SPM head by turning its two user-adjustable front knobs. Detach the AFM tipholder from the SPM head by turning the clamping screw at the back of the head.
Use tweezers to remove the existing AFM cantilever from the tipholder, then carefully grab a new silicon nitride cantilever (AFM probe) from its package and install it in place of the old cantilever. Use a light microscope to verify that the newly installed AFM cantilever is not broken.
Attach the tomato cuticle sample (a section of partially dewaxed tomato cuticle ~10 mm x 10 mm) to a stainless steel disk (sample puck) with double-sided tape. Use a light microscope to verify that the cuticle surface remains flat and smooth after placement of the sample on the puck.
Place the puck with the tomato cuticle sample onto the magnetic region at the top of the SPM scanner.
Set the front two manual adjustment screws of the scanner high by turning the knobs; set the motorized back adjustment screw to approximately the same level as the other two front screws. Make sure that all three screws are set high enough to avoid breaking the AFM tip when placing the tipholder into the SPM head.
Reinsert the tipholder into the SPM head and secure it by tightening the clamping screw at the back of the head.
After turning on the laser, align the laser spot on the AFM cantilever using the central (y) and right (x) laser adjustment knobs on the top of the head. Monitor the reflected laser beam on a piece of paper to position the laser spot exactly at the end of the AFM cantilever.