Microwave imaging and sensing for biomedical applications

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Growing interest in personal health monitoring has accelerated development and refinement of biomedical sensing technologies. Microwave imaging and sensing utilize low-power signals to assess properties of tissues related to water content, and have been proposed for applications such as detecting breast tumours. Further development and testing are required to translate these technologies from research labs to industrial partners and patients. From a research perspective, key technical challenges relate to hardware and imaging algorithms. To tackle these challenges, the long term objective of my research program is the development, implementation and testing of fast and accurate microwave imaging and sensing technologies for biomedical applications. The proposed program has 3 themes: ultra-wideband (UWB) antenna and array design, improved imaging algorithms, and feasibility assessment of new applications.Custom sensors are required to enable portable and inexpensive systems. Radar-based approaches to microwave imaging typically use UWB signals. The corresponding antennas are high performance and robust, however tend to be bulky. The goal is to design low profile UWB antennas and arrays that are placed in contact with tissues to image a localized region (e.g. part of an arm). Biomedical microwave images aim to indicate the distribution of tissues and corresponding microwave frequency properties on mm-to-cm scale. Currently, radar-based images indicate locations of changes in properties with sub-cm accuracy, while microwave tomography creates maps of properties showing cm-scale variations with computationally intensive techniques. My team has developed fast approaches to estimating average properties over cm-scale volumes. By improving these property estimates, we aim to provide information on tissue properties and distributions on cm-scale without the computational overhead of detailed tomography. Fusing property estimates and radar images will indicate tissue distributions, properties and locations of anomalies.Engineering analysis will be used to evaluate the feasibility of microwave imaging and sensing for several biomedical and veterinary problems. We have developed a framework to investigate new applications that involves simulations of realistic models and measurements of test phantoms. This analysis supports development of effective strategies for imaging, such as selection of frequency ranges. New applications include monitoring water retention in tissues (lymphedema) and assessing limbs of large animals. Impact: Portable microwave imaging systems, improved algorithms and demonstrated feasibility for new applications support translation of microwave imaging from the lab to industry and end users. This research aims to develop new tools for biomedical and veterinary problems, and may enhance existing industrial sensing technologies.