In recent years，bacterial nucleic acid detection has become a common laboratory diagnostic method owing to the continuous outbreak of diseases caused by various bacteria. Bacterial nucleic acid extraction is a key step in the classification and identification of bacteria，and also one of the important techniques for medical diagnosis and drug screening. Current bacterial nucleic acid extraction is dominated by chemical lysis methods，which have obvious drawbacks，such as large sample volume and chemical reagent contamination. Therefore，it is significantly important to develop a rapid，simple and chemically contamination-free device. In this study，we designed a microfluidic chip combining indium tin oxide（ITO） electrodes and polydimethylsiloxane（PDMS） to lysed various bacteria and extracted nucleic acids under direct current（DC） electric field. When bacteria exposed to the DC electric field，transmembrane potentials formed inside and outside of the cell membrane，leading to irreversible changes in the permeability and subsequently bacterial breakdown. Based on this principle，the effects of electric field intensity，electrode distance，lysis time，square resistance of ITO electrode and electrode width on nucleic acid extraction were investigated. Real-time fluorescence quantitative PCR，colony culture，and laser confocal microscopy were employed to jointly evaluate the performance of the chip for bacterial lysis and nucleic acid extraction. The results demonstrated that the chip could lysed a variety of bacteria（including

Escherichia coli

，

Staphylococcus aureus

，

Staphylococcus

epidermidis

，

Bacillus subtilis

，

Klebsiella pneumoniae

，

Salmonella typhimurium

，and

Pseudomonas aeruginosa

） under an electric field strength of 3.0 kV/mm within 3 s and released nucleic acids. The extracted nucleic acids can be directly applied to PCR assays without any purification. The results indicate that an appropriate electric field intensity，electrode distance，and lysis time are more conducive to nucleic acid extraction，and the optimal lysis conditions required for nucleic acid extraction differ slightly for different types of bacteria and need to be adjusted according to the properties of the particular bacteria. In contrast to other methods of bacterial lysis by electrolysis，we validated the performance of the device for bacterial lysis and nucleic acid extraction by quantitative PCR experiments，which can be better integrated with subsequent detection processes. The chip was used in conjunction with real-time fluorescent quantitative PCR to detect bacterial DNA in a linear range of 10

-18

-10

-10

mol/L，with a detection limit as low as 4.2×0

-18

mol/L. The chip designed in this work is facile to fabricate，low-cost，easily manipulated，and appropriate for point-of-care testing，especially in resource-limited settings. This study provides a simple，fast，chemical-free，and efficient nucleic acid extraction method for pathogen analysis and medical diagnosis of bacterial infections.