Thermal characterization of microwires for hypothermia-based glioblastoma treatment

Abstract

Understanding and optimizing thermal transport in biological tissue is critical for a number of thermal-based medical therapies. In particular, localized tumor cooling via an array of thin inserted microwires has been shown to be a promising technique for treating glioblastoma, the most common malignant brain tumor. Thermal conductivity of the microwire material is expected to play a key role in such hypothermia therapies. Unfortunately, thermal properties of such materials, which are often composites, are not known in advance. Moreover, such microwires may be ultra-thin, which offers additional challenges in direct measurement of thermal properties. This work presents the measurement of thermal conductivity of ultra-thin microwires (sub-100 μm diameter) using a comparative method. Validity of the experimental technique is established by measuring thermal conductivity of microwires made of standard materials. Thermal characterization of a number of candidate microwire materials for hypothermia treatment is carried out. Microwire materials that offer the highest thermal conductivity are identified. A set of thermal simulations are also carried out to understand the role of thermal conductivity of microwire materials for shallow and deep tissue hypothermia. Results presented in this work provide critical thermal characterization of a key component of tissue hypothermia, and may help in materials selection and process optimization for hypothermia based treatment of glioblastoma, as well as other hypothermia therapies.