Thermal transport measurement and modeling in tissues is of increasing importance in cardiovascular biomedicine such as focal therapy or biopreservation where the controlled and reproducible use of a thermal process can either preserve or destroy tissues with characteristic dimensions at the millimeter scale. Unfortunately, precise knowledge of the thermal properties that govern heat transfer within thin (mm scale and below) and anisotropic (i.e. multi-layered and directionally oriented) cardiovascular tissues is currently lacking in the literature. Fundamentally this is because the current standard techniques for measuring thermal properties of biological tissues involve mm-scale probes and cm-scale tissue samples. This project will address this limitation through adaptation of the 3 omega technique for these measurements. It will yield a number of important new intellectual contributions including: (1) A modified 3 omega test configuration which accommodates biological soft tissue for measurement with precise temperature and optical access; (2) A new set of property measurements in tissues with characteristic sizes from 1 mm to 10s of microns; (3) An assessment of the importance of anisotropy in cardiovascular tissue thermal properties (i.e. impact of layers and directionality in the tissue structure); and (4) A quantification of interfacial effects including contact resistance during thermal treatments in target and adjacent tissues (i.e. esophagus, lung and nerve impact of heart thermal treatments). In addition, although the initial focus will be on cardiovascular applications, this study will lay the groundwork for thermal property characterization necessary for other important preservation or therapy treatments in as yet uncharacterized biological tissues including fascia, neural, gastro-intestinal and other thin multi-layered tissues.
This project will measure the thermal properties of biological tissue with small-scale dimensions. It will utilize a measurement method used to determine properties of thin inorganic materials with suitable modifications to be applied for biological tissue. The measured data from this research will greatly contribute to the formalization of a thermal property database for many types of biological tissue not currently known, and to the development of more reliable thermal prediction models. This project will influence the development of future enhancements to biomedical devices utilizing thermal energy for disease treatment, and it could help identify new strategies for more effective preservation of pharmaceutical and food products.