High-field asymmetric-waveform ion-mobility spectrometry (FAIMS or RF-DC ion-mobility spectrometry) is a mass spectrometry technique in which ions at atmospheric pressure are separated by the application of a high-voltage asymmetric waveform at radio frequency (RF) combined with a static (DC) waveform applied between two electrodes.[1][2] Depending on the ratio of the high-field and low-field mobility of the ion, it will migrate toward one or the other electrode. Only ions with specific mobility will pass through the device.