Gain-independent compensation
The DxFLEX flow cytometer makes high-complexity testing easy. With up to 13 colors capability* you can largely eliminate complicated marker stacking and still get more information per tube. The gain-independent compensation feature on the DxFLEX flow cytometer furthermore simplifies the overall compensation procedure.
The gains of the APD (avalanche photodiode) detectors used in the DxFLEX flow cytometer can be calibrated for a linear response – leading to the predictability of the signals, in contrast to non-linear PMT-based instruments. That’s why current PMT-based clinical flow cytometry systems are complicated, and the addition of fluorescent parameters has not addressed the real challenges inherent with high-complexity testing from panel design through to data analysis.
Signal intensity versus gain: photomultiplier tube versus avalanche photodiode
In a PMT, the gain isn't linear. For example, if the voltage is increased by a factor of 2, the resulting signal, or MFI, does not double. Non-linear detection means that measurements taken at different voltages cannot be compared. Consequently, compensation needs to be empirically measured at every setting for each experiment.
Due to the reproducible semiconductor manufacturing process the gains in an APD can be calibrated for a linear response. Measured intensities are linear to the detector gain setting. This linearity means that a compensation matrix obtained at one gain setting can be used to recalculate the matrix for experiments at different gain settings that are in the linear range.
When you need to adjust PMT-detector voltages you need to:
- Rerun mixed stain
- Readjust voltages to move populations in the desired place
- Reacquire single-color stains
- Recalculate compensation matrix
- Reacquire mixed stain sample
- Assess data
It can take several cycles to find the best settings.
Compensation setup workflow
CytExpert for DxFLEX acquisition and analysis software compensation import
- The DxFLEX instrument allows you to overcome the limitations associated with PMT-based systems!
- A compensation matrix obtained at one gain setting can be used to recalculate the matrix for experiments at different gain settings that are in the linear range: The software automatically recalculates spillover values in real-time as the gains are adjusted.
On the DxFLEX instrument, you can store compensation values of fluorochromes and recalculate if necessary
