How to Calibrate AFM Tips

Mount the AFM tip onto the tip holder. The tip holder normally consists of a spring-loaded clip mounted on a plastic platform. Using tweezers, lift a new tip from its box and carefully place it upon the plastic platform. Press down on the spring-loaded clip, so that the clip lifts slightly. Using the tweezers, gently push the tip under the spring loaded clip and release it. The tip should be held firmly in place.

Place the tip onto the microscope head. Normally the tip holder will have a number of small plugs that correspond to pins on the microscope head. Carefully plug the tip holder into the pins on the microscope head.

Mount the calibration sample on the scanning stage. Calibration samples typically consist of a grid of lines of known thickness, usually around 20nm.

Image the calibration sample. Using the scan controls, bring the tip into contact with the calibration sample and measure a suitably sized image so that the grid can be seen.

Calibrate the AFM and tip. Once the image is complete, check the measured value of grid height and compare this to the thickness stated by the calibration sample manufacturer.

Calculate the ratio of actual thickness to measured thickness:

Calibration ratio = Actual thickness / Measured thickness.

For future thickness measurements using this AFM tip, use the rearranged formula to determine the correct thickness:

Actual thickness = Calibration ratio x Measured thickness