Differential Microwave Resonator Sensor Reveals Glucose-Dependent Growth Profile of E. coli on Solid Agar

• Published in: IEEE microwave and wireless components letters Vol. 30; no. 5; pp. 531 - 534
• Main Authors: Jain, Mandeep Chhajer, Nadaraja, Anupama Vijaya, Vizcaino, Bianca Marjan, Roberts, Deborah J., Zarifi, Mohammad H.
• Format: Journal Article
• Language: English
• Published: IEEE 01.05.2020
• Subjects: Bacterial growth profile; differential sensor; Frequency measurement; Glucose; glucose concentrations; growth rate; Microorganisms; Microstrip; Microwave measurement; microwave sensor; Microwave theory and techniques; Sensors
• ISSN: 1531-1309; 1558-1764
• DOI: 10.1109/LMWC.2020.2980756

This letter presents a practical application of a differential microstrip microwave sensor for label-free and real-time monitoring of Escherichia coli ( E. coli ) growth under different nutritional conditions on solid agar media. Two planar microstrip ring resonators coupled with a one-port power divider form the core of the sensing system. The sensing resonator operates at 1.509 GHz with an amplitude of −10.21 dB and the reference resonator operates at 1.798 GHz with an amplitude of −11.75 dB. The growth profile of E. coli at each glucose concentration in Luria-Bertani (LB) agar was derived by measuring the resonant amplitude variations (<inline-formula> <tex-math notation="LaTeX">\Delta {A} </tex-math></inline-formula>) and is further supported by microscopic images. A complete inhibition of growth was observed at 10% glucose concentration. This research expands the application of microwave sensors to investigate the effect of nutritional parameters on bacterial growth.