High-Throughput Antimicrobial Susceptibility Assessment Using Non- Faradaic Electrochemical Impedance Spectroscopy

In this letter, we present a label-free antimicrobial susceptibility test using non-Faradaic electrochemical impedance spectroscopy (nF-EIS) as a viable method to rapidly quantify antibiotic resistance. Different antibiotic resistant strains of Shewanella oneidensis were used as a model bacteria to measure minimum inhibitory concentration of antibiotic, namely, kanamaycin needed to kill sufficient microbes. The device consists of gold interdigitated electrodes on polyethylene terephthalate substrate that can process 50 µL volume in less than 10 min. After incubating the bacteria with kanamycin for 10 min, roughly 106 cells are analyzed using impedance spectroscopy. The observed Bode magnitude and phase plots for different strains of S. oneidensis reflect the antibiotic action on the strains and its minimum concentration requirement for its effect is determined and the data are further used to develop an equivalent electrical model to quantify the susceptibility.