Figure 3. Amplification-free detection of Ebola virus on optofluidic chip.

(a) Segments of digitized fluorescence counts above background showing concentration-dependent numbers of single RNAs; (b) concentration-dependent particle counts for off-chip (open squares) and using the automaton (solid circles) sample preparation. Negative controls (SUDV, MARV) did not create any counts (note the broken vertical scale). Dashed line: Predicted particle count determined from initial concentration and experimental parameters (tested sample volume, excitation and detection mode areas, liquid-core channel cross section). The lowest two concentrations for on-chip sample prep were reached by 50x and 460x preconcentration steps, respectively.