Compact microwave microfluidic sensors and applicator

There is a need in the industrial, chemical, biological, and medical applications for sensors capable for providing on line real-time non-destructive and non‐chemical measurements methods of liquid properties. There are huge advantages that microwave-based microfluidic sensing techniques offer over conventional methods due to the strong interaction of microwave electromagnetic fields with the molecules of polar liquids, so their properties can be revealed. Furthermore, in recent years there has been growing interest in utilizing microwaves in microfluidic heating owing to the efficient, selective, and volumetric properties of the resultant heating, which is also easily controlled. The research work presented here encapsulates: (1) The design and realization of novel microwave microfluidic microstrip sensors which can be used to characterize accurately liquid permittivities. This resonator is both compact and planar, making it suitable for a lab-on-a-chip approach. Moreover, the sensor has been developed to measure properties of multi-phase liquids where the sensor is a variant of the split ring resonator realized in a microstrip implementation. (2) A microwave microstrip sensor incorporating a split ring resonator for microsphere detection and dielectric characterization within a microfluidic channel. (3) A new dual mode microwave microfluidic microstrip sensor which has the ability to measure the liquid permittivity with temperature variations. Two quarter ring resonators were designed and fabricated. The first resonator is a microfluidic sensor whose resonant frequency and quality factor depend on the liquid sample. The second is used as a reference to adjust for any changes in temperature. (4) A microwave microfluidic applicator with electronically-controlled heating, which has been proposed, designed, and realized. The concept is based on feeding the resonator with two synchronized inputs that have a variable phase shift between them