Photodetection in Flow Cytometry: Key Considerations for the Latest Detectors Including High QE PMTs, APDs and 3rd Generation SiPMs
A CYTO 2019 Scientific Tutorial
S. Piatek, J. Butler and E. Hergert
New Jersey Institute of Technology and Hamamatsu Corporation, United States
In flow cytometry, the light scattered off an interrogated cell contains information about the cell. The role of a photodetector is to transform this information from light signal to electrical signal. This task makes a photodetector an indispensable component of a functioning flow cytometer. Transformation of information from one domain to another is never lossless. A photodetector, together with the front-end electronics, will always introduce some degree of noise and signal distortion, which impacts ubiquitous-to-flow-cytometry scattered plots. Absent of a perfect photodetector, a practitioner can choose between devices such as a photodiode, avalanche photodiode, photomultiplier tube, or silicon photomultiplier. However, each of these has unique opto-electronic and performance characteristics; therefore, the optimal performance - the smallest impact on the scatter plot – should be the guiding principle in the selection process of the photodetector. The workshop discusses the operation and performance of each device, emphasizing topics such as intrinsic gain, sources of noise, detection bandwidth, and, most importantly, how these affect the scatter plots.