title: Impedimetric method for measuring ultra-low E. coli concentrations in human urine.
abstract: 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 R(2)>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, 7×10(0) to 7×10(8) cells/ml, in urine samples with high sensitivity.
authors.affiliation: Department of Electrical Engineering, National Central University, Jhongli, Taiwan.
authors.forename: Kalpana
authors.initials: K
authors.lastname: Settu
authors.affiliation: School of Electronic and Communication Engineering, University of Chinese Academy of Sciences, Beijing, China. Electronic address: me2452858@gmail.com.
authors.forename: Ching-Jung
authors.initials: CJ
authors.lastname: Chen
authors.affiliation: College of Materials Sciences and Opto-Electronics, University of Chinese Academy of Sciences, Beijing, China. Electronic address: jentsai.liu@gmail.com.
authors.forename: Jen-Tsai
authors.initials: JT
authors.lastname: Liu
authors.affiliation: Department of Nephrology, Landseed Hospital, Taoyuan, Taiwan.
authors.forename: Chien-Lung
authors.initials: CL
authors.lastname: Chen
authors.affiliation: Department of Electrical Engineering, National Central University, Jhongli, Taiwan. Electronic address: jztsai@ee.ncu.edu.tw.
authors.forename: Jang-Zern
authors.initials: JZ
authors.lastname: Tsai
mesh_terms: D018441:Biofilms; D015374:Biosensing Techniques / Q000379:methods*; D017097:Electric Impedance; D004926:Escherichia coli / Q000302:isolation & purification*; D006046:Gold / Q000737:chemistry; D006801:Humans; D008839:Microelectrodes; D014556:Urine / Q000382:microbiology*
chemical_list: D006046:Gold
keywords: Biofilm; Electrochemical impedance spectroscopy; Escherichia coli; Interdigitated microelectrode; Urinary tract infection (UTI)