A microwave matrix sensor for multipoint label-free Escherichia coli detection

This paper presents a microwave sensor designed as a capacitive matrix for label-free Escherichia coli detection. The mean value of capacitances' change in the capacitive matrix sensor is an indicator of the bacteria detection. The theoretical analysis was confirmed by the realization of an exemplary sensor chip manufactured using the United Monolithic Semiconductor (UMS) PH25 process on a 100 μm thick GaAs substrate and measurements of various concentrations of Escherichia coli in the frequency range 1-3 GHz. The matrix topology of the sensor together with biofunctionalization of the sensor surface with polyclonal anti-Escherichia coli antibody allow to obtain high detection sensitivity on various concentrations of Escherichia coli reaching 10³ CFU/ml. The obtained results are promising for future biomedical applications, in terms of specific bacteria presence detection.