A method of target molecule detection includes simultaneously obtaining a first signal from a first working electrode and a second signal from a second working electrode, wherein the first signal is responsive to interaction of the first recognition element with the target molecule in a sample, and the second signal is indicative of background noise from the sample. The method further includes generating a modified signal that is proportional to an instantaneous difference between the first and second signals, wherein the modified signal indicates an amount of the target molecule present in the sample.