Programmable Dielectrophoretic Enrichment of Microorganisms on CMOS-Fabricated Nanoelectrode Arrays

This study utilizes a nanoelectrode array chip fabricated using CMOS processes to develop a microbial manipulation and enrichment platform based on dielectrophoresis (DEP). Microbial enrichment can be achieved using a regularly patterned nanoelectrode array without requiring specifically designed geometric trapping structures, while maintaining effective performance at a low operating voltage of 20 Vpp. Yeast and E. coli were selected as model microorganisms. Two enrichment methods were proposed and applied, both achieving an enrichment factor of approximately 2 in the E. coli enrichment experiments. In addition, the effect of applied waveforms on microbial enrichment was investigated. Theoretical analysis indicated that, under the ideal waveform assumption and at the same peak-to-peak voltage, a square wave could be used to generate an approximately twofold greater dielectrophoretic force than a sine wave, while experimental results demonstrated differences in microbial enrichment between the two waveforms. Separation and independent enrichment were also achieved in a mixed microbial system, leading to the development of an optimal separation and enrichment strategy. The results further indicate that dipole-dipole interactions influence the movement of microorganisms in a mixed system. Under experimental conditions, a distance greater than 5.35 μm between the two microorganisms was required for dielectrophoretic forces to dominate their movement. In summary, this study demonstrates that efficient microbial manipulation, separation, and enrichment can be achieved through simple electrode arrays and manipulation methods.