The tradeoff between increased scanning periodicity for alkylthiolate layer preservation in light of thermal effects and reduced scanning for aptamer preservation is summarized in Table . It has recently been shown by our group that partial scanning (Figure ) about the redox peak can reduce the electrochemical stress on the sensor while still providing a robust redox-current for determining sensor response to analyte, which therefore may provide even greater longevity results than the unoptimized results demonstrated herein. Table . Summary of the tradeoffs between infrequent (once daily) and frequent (every 30 s) scanning at 4 ˚C and 37 ˚C in PBS (Figure ) or serum (Supplemental Figure ). Fouling affects electron transfer rates and has a significant impact on freedom of mobility of the aptamer (Figure ). While MCO passivated sensors are more resistant to monolayer desorption in multiday operation and maintain a more stable redox tag current relative to MCH sensors (Figure ), both MCH and MCO based sensors suffer from a severe loss in sensor response (i.e., sensitivity) to vancomycin molecules after only 3 days of repeated scanning in serum at 37 ˚C (Figure ). Maximum sensor responses were reduced by ~4X for MCH sensors, whereas those for MCO sensors decreased moderately by 1/3 rd compared to freshly prepared sensors. This large reduction in sensor response was not seen in sensors repeatedly scanned in PBS at 37 ˚C, as titration curves after 7 days only showed a relative reduction in maximum response of 20% for MCH sensors and virtually no loss in maximum response for MCO sensors (Figure ). This further suggests that over multiple days, rearrangement of the biofouled layer can hinder the physical mobility of aptamer molecules and prevent conformational change in the presence of analyte. With more aptamer molecules being incapable of bringing their redox reporter closer to the electrode surface, while still contributing to the redox tag current measured in analyte-free serum, a higher concentration is needed to drive a higher proportion of the unrestrained aptamer population toward the bound state. Of note, MCO sensors still showed appreciable sensor response after 7 days of continuous scanning in serum at 37 ˚C, albeit with large interelectrode error which could significantly impair calibration efforts (see Supplemental Figure ).