High-field asymmetric-waveform ion-mobility spectrometry (FAIMS or RF-DC ion-mobility spectrometry) is a mass spectrometry

Mass spectrometry

Mass spectrometry is an analytical technique that measures the mass-to-charge ratio of charged particles.It is used for determining masses of particles, for determining the elemental composition of a sample or molecule, and for elucidating the chemical structures of molecules, such as peptides and...

 technique in which ions at atmospheric pressure

Atmospheric pressure

Atmospheric pressure is the force per unit area exerted into a surface by the weight of air above that surface in the atmosphere of Earth . In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point...

 are separated by the application of a high-voltage asymmetric waveform at radio frequency

Radio frequency

Radio frequency is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals...

 (RF) combined with a static (DC

DC bias

When describing a periodic function in the frequency domain, the DC bias, DC component, DC offset, or DC coefficient is the mean value of the waveform...

) waveform applied between two electrodes. Depending on the ratio of the high-field and low-field mobility of the ion, it will migrate toward one or the other electrode

Electrode

An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit...

. Only ions with specific mobility will pass through the device.