Impedimetric method for measuring ultra-low E. coli concentrations in human urine

Kalpana Settu, Ching Jung Chen, Jen Tsai Liu, Chien Lung Chen, Jang Zern Tsai

Research output: Contribution to journalArticlepeer-review

56 Scopus citations


In this study, we developed an interdigitated gold microelectrode-based impedance sensor to detect Escherichia coli (E. coli) in human urine samples for urinary tract infection (UTI) diagnosis. E. coli growth in human urine samples was successfully monitored during a 12-h culture, and the results showed that the maximum relative changes could be measured at 10Hz. An equivalent electrical circuit model was used for evaluating the variations in impedance characteristics of bacterial growth. The equivalent circuit analysis indicated that the change in impedance values at low frequencies was caused by double layer capacitance due to bacterial attachment and formation of biofilm on electrode surface in urine. A linear relationship between the impedance change and initial E. coli concentration was obtained with the coefficient of determination R2>0.90 at various growth times of 1, 3, 5, 7, 9 and 12h in urine. Thus our sensor is capable of detecting a wide range of E. coli concentration, 7×100 to 7×108 cells/ml, in urine samples with high sensitivity. coli in urine samples using interdigitated microelectrode sensor.coli concentration was measured in urine by growth time-graded impedance monitoring approach.coli concentrations at various growth times.

Original languageEnglish
Pages (from-to)244-250
Number of pages7
JournalBiosensors and Bioelectronics
StatePublished - 5 Apr 2015


  • Biofilm
  • Electrochemical impedance spectroscopy
  • Escherichia coli
  • Interdigitated microelectrode
  • Urinary tract infection (UTI)


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