Feasibility study to increase the sensitivity of a microwave microstripline bandpass filter based biosensor for the detection of bacteria in water

This thesis focuses on ways to increase the sensitivity of a microstrip line bandpass filter based biosensor for the detection of bacteria in water. The biosensor output is the change in response of the coupled line bandpass filter when bacteria adhere to the surface of the filter circuit resulting from a change of permittivity of the region above the filter circuit. This study has shown that the sensitivity of the biosensor can be increased when the bandwidth of the coupled line bandpass filter is increased. In addition, the change in response of the biosensor, quantified by a shift in the center frequency of the bandpass filter is observed to increase with increasing thickness of a dielectric overlay that simulates bacteria adhering in multilayers to the biosensor surface. A further advancement in the design of the biosensor is presented based on a dual band stepped impedance bandpass filter, wherein the possibility of using this design for the simultaneous detection of two types of bacteria is presented.