Figure 2.

Electrical response of insulated BioFET devices in phosphate-buffered saline (PBS, a biological buffer). Devices' responses to streptavidin are shown. In one device, receptor protein streptavidin was directly adsorbed to the sensing channel (open circles), and in another, streptavidin was attached to the channel by interaction with a biotinylated SAM on the surface (open triangles). The electrical properties of these devices are changed substantially by streptavidin directly bound to the sensing channel. Compare that device (open circles) with the device with no SAM (filled squares). Note that the electrical characteristics of a device with no SAM (and receiving no streptavidin, filled squares) are virtually identical to the characteristics of a device binding streptavidin via a biotinylated SAM (open triangles), indicative of the low sensitivity of the device when receptor and analyte are bound using this biotinylated SAM (accepted JRSI-2007-1033).