High-performance electrical variable resistor sensor for E.coli O157:H7 detection

Nowadays interdigitated electrode (IDE) based sensors have stimulated increasing interest in the application of biosensor field. A large number of finger electrodes as comb structure gain high sensitivity through electrical measurements. In this research study, we have demonstrated a novel mechanism as biocontrollable variable resistor through solid state conducting Polymer Bridge to detect single-stranded E. coliO157:H7 DNA. The gap of AuIDE sensor on Si substrate was used to create DNA biosensor. Functionalization steps of the AuIDE to create biosensor was based on silanization by APTES, immobilization of E.coli O157:H7 synthetic probe single-stranded DNA (ssDNA), blocking with tween-20. The well fabricated AuIDE biosensor was physically characterized by using scanning electron microscope (SEM) and high power microscope (HPM). Molecular assembly of the functionalized biosensor was analyzed structurally using Energy-dispersive X-ray spectroscopy (EDX) and electrically using current-voltage measurements (I-V). The selectivity of the biosensor was identified electrically using complementary, non-complementary and single base mismatch ssDNA targets. Blocking step with tween-20 was important to detect target specifically. The obtained variations in current indicate the varied concentrations of E. coli targets and it is confirmed that biosensor is suitable to detect different concentrations in the range from 10 fM to 10 μM.