CMOS Ion Sensitive Field Effect Transistors for Highly Sensitive Detection of DNA Hybridization

CMOS (complementary metal oxide semiconductor) biosensors are promising to provide label-free and highly sensitive detection with high throughput. Ion-sensitive field effect transistors (ISFETs) can sensitively detect the charges carried by target analyte upon specific binding. This work studies the hybridization of complementary DNA (deoxyribonucleic acid) strands by ISFETs implemented in a 0.35-μ m CMOS process. Three designs of different electrode and transistor sizes are implemented, with pH sensitivities measured between 27 to 32 mV/pH in terms of the threshold voltage shift. The increase of current in the p-type ISFETs due to hybridized target DNA molecules is successfully detected near femtomolar concentration, which is among the best sensing resolution for CMOS ISFETs.