PFM is a contact-mode technique for measuring the electromechanical response of materials, typically piezo- or ferroelectric. DART-PFM, a primary measurement mode, minimizes crosstalk between piezoelectric signals and topography.

It uses two lock-in amplifiers to apply frequencies of equal amplitude on either side of the contact resonance peak. When the resonance shifts, amplitude changes occur; the feedback system adjusts the excitation frequency to cancel these changes, yielding clear topography and piezoelectric signals.

Because most PFM samples are rough, hard materials, tip wear is a key concern.