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A sensor array concept has been developed using microstrip-line-excited split-ring resonators (SRRs). With this structure it is possible to spatially resolve the dielectric properties of a Material Under Test (MUT). The SRRs are designed to have different resonant frequencies and are decoupled from each other to indicate the dielectric properties of the MUT and its location within the array. Several prototype sensors have been realized and tested to prove the concept.

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Microwave sensors in medical environments play a significant role due to the contact-less and non-invasive sensing mechanism to determine dielectric properties of tissue. In this work, a theranostic sensor based on Split Ring Resonators (SRRs) is presented that provides two operation modes to detect and treat tumor cells, exemplary in the liver. For the detection mode, resonance frequency changes due to abnormalities are evaluated, and in the treatment mode, microwave ablation is performed. The planar sensor structure can be integrated into a needle like a surgery tool that evokes challenges concerning size limitations and biocompatibility. To meet the size requirements and provide a reasonable operating frequency, properties of oval shaped SRRs are investigated. By elongating the radius of the SRR in one direction, the resonance frequency can be decreased significantly compared to circular SRR by a factor of two below 12 GHz. In order to validate the detection and treatment characteristics of the sensor, full wave simulations and measurements are examined. Clear resonance shifts are detected for loading the sensor structures with phantoms mimicking healthy and malignant tissue. For treatment mode evaluation, ex vivo beef liver tissue was ablated leading to a lesion zone 1.2 cm × 1 cm × 0.3 cm with a three minute exposure of maximum 2.1 W.

A dual mode tool design to analyze organic tissue and locally perform thermal ablation treatment is presented. The tool is made of an array of split-ring resonators. It can operate on a sensing mode to track the relative dielectric changes from the organic tissue and on a treatment mode to perform thermal ablation at different input powers. The measurements were done with phantoms of human tissue. The tool is able to focus a hot spot of approximately 0.2mm with a temperature of 109 °C at an input power of 10W.

A particulates mass flow meter has been developed using a composite right/left-handed transmission line resonator. The presented sensor principle promises the possibility to design precise particulate solids mass flow meter with moderate costs. The autocorrelation function is applied to the CRLH-resonator in order to detect the velocity information and the material density from a single measurement. The areas of application of these sensors are gas/solids, gas/liquid and liquid/solids flows in various industrial applications.