Electrocontrolled Injection-Coupled Droplet Microfluidic Platform for Antimicrobial Resistance Screening

Droplet microfluidics enables high-throughput single-cell analysis but encounters inherent challenges in antibiotic susceptibility testing (AST), primarily stemming from inadequate control over single-bacterium encapsulation and droplet manipulation. Herein, we report an integrated droplet microfluidic platform that achieves precise bacterial encapsulation via electrocontrolled injection. Flow parameters were systematically optimized to generate highly monodisperse droplets with excellent morphological stability, while an integrated pressure–volume calibration method coupled with a minimum electroinjection threshold ensured accurate regulation of injection volume and reliable intradroplet reagent delivery. By coencapsulating Escherichia coli harboring the pGLO plasmid and resazurin, dual-fluorescence monitoring was realized via GFP fluorescence, indicating bacterial viability and proliferation, as well as resorufin fluorescence, which is produced from the reduction of resazurin, reflecting metabolic activity. This platform enables controllable encapsulation down to the single-bacterium level and completes AST within 3 h via fluorescence readout. Integrating miniaturization, high throughput, and low reagent consumption, this multichannel droplet microfluidic system provides a robust and efficient tool for rapid antimicrobial resistance detection, with considerable potential for clinical translation.