User manual

Droplet Digital
™
PCR Applications Guide | 5
Droplets are spaced out individually for fluorescence reading by the droplet reader
(Figure 1.7). Fluorescence in two channels is then measured for individual droplets.
Positive droplets, which contain at least one copy of the target DNA molecule, exhibit
increased fluorescence compared to negative droplets (Figure 1.8).
Fig. 1.7. Separating individual droplets in the QX100 droplet reader.
Fig. 1.9. Each droplet from a sample is plotted on the graph of fluorescence intensity vs. droplet number.
Fig. 1.8. Fluorescence readings are measured for each droplet in two channels.
ddPCR Data Analysis
Droplet Digital PCR data can be viewed as a 1-D plot with each droplet from a sample
plotted on the graph of fluorescence intensity vs. droplet number. In Figure 1.9, all positive
droplets, those above the red threshold line, are scored as positive and each is assigned a
value of 1. All negative droplets, those below the red threshold line, are scored as negative
and each is assigned a value of 0.
Droplet Digital
™
PCR
0 2,000 4,000 6,000 8,000 10,000 12,000 14,000
Event number
Channel 1 amplitude
14,000
12,000
10,000
8,000
6,000
4,000
2,000
0
3,323