Bacterial contamination of water is still a critical threat to public health; seeking efficient water disinfection approaches is of great significance. Here, we show that locally enhanced electric field treatment (LEEFT) by electrodes modified with nanoscale tip structures can induce ultrafast bacteria inactivation with nanosecond electrical pulses. A lab-on-a-chip with gold nanowedges fabricated on the electrodes is developed for an operando investigation. The bacteria at the nanowedge tips are inactivated by electroporation due to the lightning rod effect. A single 20 ns pulse at 55 kV/cm has achieved 22.3% bacteria inactivation. Ten pulses at 40 kV/cm achieved 95.2% inactivation. LEEFT lowers the applied electric field by 8 times and shortens the treatment time by 10<sup>6</sup> times compared to the system without nanowedges. Both gram-positive and gram-negative bacteria, including antibiotic-resistant bacteria, are inactivated with nanosecond pulses in LEEFT. According to simulation, the membrane of the cell located at the nanowedge tip is charged much faster and to a much higher level, since it is directly charged by the charges concentrated at the nanowedge tip, which leads to instant electroporation and cell inactivation. This work demonstrates the potential application of LEEFT for highly efficient water disinfection.

Ultrafast Bacteria Inactivation by Locally Enhanced Electric Field Treatment (LEEFT) with nanosecond pulses

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ACS Fall 2022

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