A Waveguide Resonator Sensor for Bacterial Growth Monitoring: Towards Antibiotic Susceptibility Testing

This paper proposes a waveguide resonator biosensor for real-time and non-contact BGM with future application in AST. The sensor operated based on creating a resonant section sandwiched between two inductive irises. The resonant section consisted of an opening through which the bacterial sample in the test tube in placed, creating material perturbations. Bacteria growth caused alterations in the complex permittivity of the resonant section, changing the resonant characteristics that were monitored in the reflection coefficient of the waveguide. Experimental results indicated a ~6.7 dB increase in the magnitude of the reflection coefficient for the growth of 50 μL of E. coli in 5 mL of Luria-Bertani (LB) broth at 37 ºC, over a period of 12 hours. To evaluate the capability for AST, investigations were extended to monitor the bacterial growth trends in the presence of different antibiotic concentrations in the media.