Researchers addressed these challenges by developing field-effect transistor (FET) biosensors based on highly uniform semiconducting carbon nanotube (CNT) thin films. The mass-produced CNT FET sensors, combined with oligonucleotide aptamers as efficient bioreceptors, enabled reliable and reproducible sub-femtomolar detection in full human serum for Aβ42 and Aβ40 peptides, outperforming other methods reported to date. The biosensors reduced adsorption of biological substrates to the sensor by using multiple blocking steps, resulting in selectivity ratios of up to 730% (Aβ40) and 800% (Aβ42). The aptamer-functionalized CNT FET biosensors exhibited a large dynamic range (>10 4 ), rapid response time (several minutes), and low variation (<10%) and could be delivered as a low-cost and rapid clinical detection technology for the early diagnosis and mass screening of AD. This platform could help bring complex laboratory-based and expensive diagnostic tools to the point of care. Overall, the researchers produced an aptamerfunctionalized FET biosensors that utilized randomly oriented semiconducting CNT networks.