Patent ID: 9632030
Date: 2017-04-25
CPC Classifications: G01N

Claim:
1. A method for determining an average fluorescent lifetime of a fluorescent particle in a flow cytometer comprising: detecting at a first detector a scatter signal and detecting at a second detector a fluorescent signal from a particle as the particle transits within microseconds through an interrogation beam of Gaussian profile emitted from a non-modulated light source having an excitation wavelength that causes the particle to fluoresce in the flow cytometer wherein the first detector and the second detector are temporally phase locked and the interrogation beam has a beam path width that is wider than the fluorescent particle detected; digitizing the scatter signal from the first detector and digitizing the fluorescent signal from the second detector with a digitizer having a high sampling rate to produce a digitized scatter waveform and a digitized fluorescence waveform for the fluorescent particle; calculating a point on the digitized scatter waveform and a corresponding point on the digitized fluorescence waveform using a same method; and determining a time delay if any between the calculated point on the digitized scatter waveform and the calculated point on the digitized fluorescent waveform for the fluorescent particle wherein the time delay is the average fluorescent lifetime of the fluorescent particle and wherein the average fluorescent lifetime is determined as the particle transits through the flow cytometer.