English: Left: This image displays the electrode surface upon which the aptamer is immobilized and the self assembling monolayer (SAM) passivates the surface where aptamers are not bound. The redox reporter (blue) is far away from the gold electrode on the unfolded (or partially unfolded) DNA in the absence of target molecule (purple). Upon target binding, the DNA changes structure by folding, bringing the redox reporter closer to the electrode surface. Right: The change in current produces a signal relative to the baseline. The baseline signal is the signal generated without target. The baseline represents the redox activity of the aptamer vs. Ag/AgCl.