MultiMode Probe Holders

The probe holder (colloquially referred to as the 'cantilever holder') for the MultiMode AFM head is a small metal or acrylic block with a handle for the user and circuit connectivity to the microscope. The holders are designed to maintain the probe substrate firmly at the proper angle for AFM or STM operation. The standard holder is used for operation in air and has a cut out region to allow the laser to come from above and reflect off of the cantilever. A clear glass window allows the laser to reach the cantilever in during fluid cell operations. Probe holders include the cantilever piezoelectric stack, electrical contacts to the drive circuits, and grooves that mate with the head positioning screws at the end of the scanner.

You can easily change the probe holder on the microscope for different operating modes:

The available probe holders for various applications are summarized in MultiMode Probe Holder Selection.

Standard Probe Holder

The standard probe holder contains a piezoelectric stack to oscillate the cantilever for TappingMode AFM. The same cantilever holder is used for Contact AFM, but no voltage is applied to the piezo stack.

Figure 1: Bottom (A) and Top (B) views of the standard MultiMode probe holder. Pressing the spring clip release button elevates the spring clip from the substrate mounting groove, allowing a probe to be inserted into the holder.

Fluid Probe Holder

The fluid cell probe holder provides an optically transparent cover over the back of the cantilever to maintain the optical path of the laser beam constant when the tip is submerged in a fluid medium. If the probe holder was not immersed in the fluid medium, imaging with the tip submerged in fluid would be impossible due to variable surface scattering effects. These effects cause the reflected laser beam to move randomly during imaging, rendering the reflected signal useless for SPM imaging. For more information see Probes and Accessories for Fluid Operation.

Figure 2: Top view of MultiMode fluid cell. This surface should be downward and pressed gently into the table to release the spring clip and mount a probe in the substrate mounting groove.

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