Understand the basic premise behind using AFM for the purpose of detecting the pH. Detecting pH is possible through other means, but as an article in the "Journal of Physical Chemistry" notes, AFM techniques make it possible to study the acid-base properties of substances that have inhomogeneous or rough substrates. This means that the measurement of pH using one of these microscopes requires a way to overcome these potential barriers.
Add the required liquid electrolyte to the substance being measured. The measurement of the pH of substances with what would otherwise be an immeasurable substrate can only occur when a substance is used that will allow the AFM to accurately detect any particle changes that may have occurred as a result of the mixture. For instance, a Si-OH compound may exchange protons with water when immersed in it and has an effect on the way that the AFM measures the substance.
Determine the force exhibited by the surface tension of the aqueous substance. Once the solution has reacted with the compound being measured, the pH can be determined by examining the force of the topography of the substance by mapping it out. The AFM uses a small tip that comes into contact with the substance. The tip is slowly dragged across the surface while the computer of the AFM measures the displacement of the tip across the entire measurement. Each image takes about five to 10 minutes to complete and is produced when the microscope's tip provides feedback to the computer scanners, which then record the measurements.