An integrated microsystem with dielectrophoresis enrichment and impedance detection for detection of Escherichia coli

Authors: WANG, RENJIE - Chongqing University; XU, YI - Chongqing University; LIU, HAITAO - Chongqing University; PENG, JINLAN - Chongqing University; IRUDAYARAJ, JOSEPH - Purdue University; CUI, FEIYAN - Chongqing University

Submitted to: Biomedical Microdevices
Publication Type: Review Article
Publication Acceptance Date: 4/21/2017
Publication Date: 6/1/2017
Citation: Wang, R., Xu, Y., Liu, H., Peng, J., Irudayaraj, J., Cui, F. 2017. An integrated microsystem with dielectrophoresis enrichment and impedance detection for detection of Escherichia coli. Biomedical Microdevices. 19(2):34.

Interpretive Summary:

Technical Abstract: An integrated microsystem device with matched interdigitated microelectrode chip was fabricated for enrichment and detection of Escherichia coli O157:H7. The microsystem has integrated with positive dielectrophoresis (pDEP) enrichment and in situ impedance detection, whose total volume is only 3.0 × 10-3 m3, and could provide impedance testing voltages of 0 approximately 10 V, detection frequencies of 1 KHz approximately 1 MHz, DEP excitation signals with amplitude of 0 approximately 10 Vpp and frequencies of 1KHz approximately 1 MHz, which fully meets the demands of pDEP enrichment and impedance detection for bacteria. The microfluidic chip with interdigitated microelectrodes was manufactured by microfabrication methods. The interdigital microelectrode array has sufficient contact area with a bacterial suspension to improve enrichment efficiency and detection sensitivity. Bacteria in the interdigital microelectrode area of the microfluidic chip were firstly captured and enriched by pDEP. Then, in situ impedance detection of the enriched bacteria was realized by switching test conditions. Using the self-assembly microsystem, a novel quantitative detection method was established and demonstrated to detect Escherichia coli O157:H7. Experimental results showed that the detection limits of Escherichia coli O157:H7 was 5 × 104 cfu mL-1, and testing time was only 6 min under the optimized detection voltage of 100 mVand frequency of 500 KHz. The method was successfully used to detect Escherichia coli O157:H7 in synthetic chicken synthetic samples.