Microelectrical noise detector for rapid, specific, and sensitive identification of bacteria

Abstract

Recently, sensing of phase-triggered ion cascades (SEPTIC), a nanotechnology for rapid detection of live, pathogenic bacteria on the scale of minutes with unparalleled specificity, has drawn a lot of attention. SEPTIC utilizes a nanowell device, consisting of two metal electrodes with a gap between 5 and 200nm, to probe the ion effluxes from specific bacteria when they are infected by phages. Whether the effluxes occur can be identified by evaluating the power spectral density of the voltage noise in the nanowell. This article presents further development of SEPTIC, using E. coli, E. coli phage T7, and a control bacteria as analytes. A microwell, identical to a nanowell except that the gap is 4μm, proved capable of probing the ion efflux as well. When ion efflux occurred, abnormal pulses that were much higher than the noise level and lasted for 0.1–0.3s were observed in the voltage noise output from the microwell. These durations agree with the average duration of ion efflux. While in negative tests, observed abnormal pulses were much shorter than 0.1s. Also, positives showed 1∕f noise while negatives showed white noise in 1–10Hz. No false positives or negatives were observed. Given the size of microwell and the simplified detection electronics, the cost of SEPTIC is significantly reduced and the robustness is well improved, indicating very promising applications in clinical diagnosis and biodefense.