Fig. 3. Selective detection of single viruses. (A) Conductance vs. time data
recorded simultaneously from two silicon nanowires elements, red and blue
plots, within a single device array after introduction of an influenza A solution.
(Inset) Frequency of single virus events as a function of virus solution concentration.
(B) Conductance changes associated with single influenza A virus binding
unbinding as a function of solution pH. (C) Conductance (Upper) and optical
(Lower) data recorded simultaneously vs. time for a single silicon nanowire device
after introduction of influenza A solution. Combined bright-field and fluorescence
images correspond to time points 1–6 indicated in the conductance data;
virus appears as a red dot in the images. The solid white arrow in image 1
highlights the position of the nanowire device, and the dashed arrow indicates
the position of a single virus. Images are 8 8 m. All measurements were
performed with solutions containing 100 viral particles per l.