A microfluidic device for label-free detection of Escherichia coli in drinking water using positive dielectrophoretic focusing, capturing, and impedance measurement.
While sensors that allow for high-throughput enumeration of microorganisms within drinking water are useful for water quality monitoring, it is particularly challenging to accurately quantify microorganisms that are present in low numbers (<100 CFU/mL) in a high-throughput manner. Negative dielectrophoresis (nDEP) is typically utilized in DEP-based cell focusing methods; however, due to its low conductivity, drinking water cannot be analyzed by this approach. Here, we report a positive DEP (pDEP)-based Escherichia coli detection system that is integrated with a focusing and sensing electrode. By incorporating a passivation layer, we avoided issues with adhesion of E. coli to the electrode, and achieved efficient cell focusing under high flow rate conditions (1500 μL/h). The resulting focused E. coli cells were then trapped on the sensor electrode, resulting in changes in impedance. The proposed system was evaluated using four different E. coli populations (150-1500 CFU/mL). We successfully enumerated populations as low as 300 CFU/mL within 1 min, and the signal variation was 1.13±0.37%. The device introduced in this study provides the basis for the development of portable, highly sensitive microorganism sensors that enable rapid detection of bacteria in drinking water.
Institute of Medical System Engineering (iMSE), Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, Republic of Korea.
Myounggon
M
Kim
Department of Medical System Engineering, GIST, Gwangju 500-712, Republic of Korea.
Taekeon
T
Jung
L&E R&D Center, LG Electronics Inc., Gasan-dong Geumcheon-gu, Seoul, Republic of Korea.
Youngjin
Y
Kim
L&E R&D Center, LG Electronics Inc., Gasan-dong Geumcheon-gu, Seoul, Republic of Korea.
Changgeun
C
Lee
L&E R&D Center, LG Electronics Inc., Gasan-dong Geumcheon-gu, Seoul, Republic of Korea.
Kyungchul
K
Woo
School of Mechatronics, GIST, Gwangju 500-712, Republic of Korea.
Jae Hun
JH
Seol
Institute of Medical System Engineering (iMSE), Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, Republic of Korea; Department of Medical System Engineering, GIST, Gwangju 500-712, Republic of Korea; School of Mechatronics, GIST, Gwangju 500-712, Republic of Korea. Electronic address: syang@gist.ac.kr.
Sung
S
Yang
D058491:Bacterial Load / Q000295:instrumentation*; D015374:Biosensing Techniques / Q000295:instrumentation; D002469:Cell Separation / Q000295:instrumentation*; D060766:Drinking Water / Q000382:microbiology*; D004586:Electrophoresis / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013194:Staining and Labeling; D014873:Water Pollutants / Q000302:isolation & purification*
D060766:Drinking Water; D014873:Water Pollutants
Drinking water; Escherichia coli; Label-free detection; Microorganism enumeration; Positive dielectrophoresis (pDEP)