International audienceWe report on a new topology of coupling between substrate integrated circular cavities designed to produce particular filtering functions through combination with the classical iris-based coupling. This coupling is achieved by a grounded coplanar line etched at the top of cavities. This topology was used to realize a Ku-Band third-order filter, whose synthesis, electromagnetic simulation with HFSS, and experimental performances are presented here
Three microwave sensors are used to track the glucose level of different human blood plasma solutions. In this paper, the sensors are evaluated as glucose trackers in a context close to real human blood. Different plasma solutions sets were prepared from a human blood sample at several added glucose concentrations up to 10 wt%, adding also ascorbic acid and lactic acid at different concentrations. The experimental results for the different sensors/solutions combinations are presented in this work. The sensors show good performance and linearity as glucose level retrievers, although the sensitivities change as the rest of components vary. Different sensor behaviors depending upon the concentrations of glucose and other components are identified and characterized. The results obtained in terms of sensitivity are coherent with previous works, highlighting the contribution of glucose to the dielectric losses of the solution. The results are also consistent with the frequency evolution of the electromagnetic signature of glucose found in the literature, and are helpful for selecting frequency bands for sensing purposes and envisioning future approaches to the challenging measurement in real biological contexts. Discussion of the implications of the results and guidelines for further research and development of more accurate sensors is offered.
The measurement of glucose concentration finds interesting potential applications in both industry and biomedical contexts. Among the proposed solutions, the use of microwave planar resonant sensors has led to remarkable scientific activity during the last years. These sensors rely on the changes in the dielectric properties of the medium due to variations in the glucose concentration. These devices show electrical responses dependent on the surrounding dielectric properties, and therefore the changes in their response can be related to variations in the glucose content. This work shows an up-to-date review of this sensing approach after more than one decade of research and development. The attempts involved are sorted by the sensing parameter, and the computation of a common relative sensitivity to glucose is proposed as general comparison tool. The manuscript also discusses the key points of each sensor category and the possible future lines and challenges of the sensing approach.
International audienceThis paper proposes several topologies of filters based on substrate integrated circular cavities (SICCs). SICC works on TM modes and the benefits of this technology are mainly an increased quality factor and a better design flexibility. Filters are made from cylindrical cavities integrated into a planar substrate and are fed by microstrip lines through coupling slots. Cavities are inter-coupled by irises. One-order, second-order and third-order filters are presented. Preliminary measurement data are compared to those from simulations performed with a 3-D electromagnetic structure simulator. These filters rely on the SICC concept, whose principle is explained hereafter
A new reconfigurable frequency cavity compatible with planar technology has been designed, manufactured and measured. An original tuning solution is proposed, based upon the insertion of vertical capacitive posts integrated within SIW cavities. One extremity of each post is connected to a floating metallic ring, located on the substrate supporting the SIW cavity. The frequency agility is obtained once the metallic ring is connected to the ground plane by short-circuited the corresponding annular slot using surface actuators. Such combination of volumic cavity and planar activation leads to reconfigurable filters with high Q values and simplified tuning control conditions.
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