Preliminary results for broadband electrical detection of live bacteria

For the first time, broadband (0.5-20 GHz) electrical detection of live bacteria was successfully demonstrated on E. coli, despite their being small and adherent compared to mammalian cells such as Jurkat T-lymphoma human cells that had been detected by using a similar coplanar waveguide in conjunction with a microfluidic channel. Critical to the success was in suppressing the background drift of the insertion and return losses to the order of 0.01 dB. Presently, it is estimated that approximately 10
⁴
E. coli were required to yield a statistically significant signal in the insertion/return losses. Therefore, to detect a single bacterium, the measurement sensitivity and the background stability need to be further improved by orders of magnitude in the future.