Fig. 2.

Schematic of a proposed label-free GMR sensor system (single channel illustrated) operating in reflection mode. The collimated beam from a broadband source is incident on the sensor at normal incidence. The reflected spectral response is monitored in real time with an optical spectrum analyzer. As binding events occur at the sensor surface, resonance peak changes (only one polarization depicted in plot) can be tracked as a function of wavelength ($\mathrm{\Delta }\lambda$). Modified from Ref. 38.