title: A simple mathematical model for electric cell-substrate impedance sensing with extended applications.
abstract: This paper presents a simple mathematical model to predict the impedance data acquired by electric cell-substrate impedance sensing (ECIS) at frequencies between 25 Hz and 60 kHz. With this model, the equivalent resistance (R) and capacitance (C) of biological samples adhered on gold surfaces could be more precisely measured at 4 kHz. ECIS applications were extended for real-time monitoring of living bacteria cultivated in Luria Bertani (LB) culture medium by two different approaches. In the former, we used a ferri/ferrocyanide redox couple in LB medium as an indicator for bacterial multiplication. Because the redox couple was toxic to some bacteria, we developed a second approach, in which l-cysteine self-assembled monolayers (SAM) on gold electrodes were used to detect living bacteria. The l-cysteine SAM could also be detected by ECIS. Unlike traditional impedance microbiological methods which need special culture media with low ions, our procedures significantly enhanced signal/noise ratios so bacteria could be detected in general purpose culture media. It was easy and convenient to obtain bacterial doubling times and evaluate the resistance of bacteria to antibiotics from ECIS spectra.
authors.affiliation: Institute for Biocomplexity and Informatics, University of Calgary, 2500 University Driver NW, Calgary, Alberta, Canada. caide.xiao@Ucalgary.ca
authors.forename: Caide
authors.initials: C
authors.lastname: Xiao
authors.forename: John H T
authors.initials: JH
authors.lastname: Luong
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D018407:Bacterial Physiological Phenomena / Q000187:drug effects* / Q000528:radiation effects; D001681:Biological Assay / Q000295:instrumentation*; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D003198:Computer Simulation; D017076:Computer-Aided Design; D003217:Conductometry / Q000295:instrumentation* / Q000379:methods; D004574:Electromagnetic Fields; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008954:Models, Biological; D010992:Plethysmography, Impedance / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D000900:Anti-Bacterial Agents