Highly Sensitive DNA Detection Beyond the Debye Screening Length Using CMOS Field Effect Transistors

Field effect transistors are considered one of the key technologies to provide real-time and label-free biodetection. Direct detection in physiological solutions is, however, severely limited by the Debye charge-screening effect of the electrical double layer. Most measurements are therefore performed indirectly in diluted ionic-strength solutions. This study proposes a general technique based on modulation of the surface electric field of the CMOS (complementary metal oxide semiconductor) extended-gate field effect transistors (EGFETs) to investigate the screening effect on hybridized DNA (deoxyribonucleic acid) signals from 1 MHz to 15 MHz. The 32 EGFET sensor array exhibited a floating-gate potential change of 17.4 mV/log[DNA] from 1 fM to 100 pM with a near picomolar-level resolution and a response time below 8 minutes.