title: A Micro-Thermal Sensor for Focal Therapy Applications.
abstract: There is an urgent need for sensors deployed during focal therapies to inform treatment planning and in vivo monitoring in thin tissues. Specifically, the measurement of thermal properties, cooling surface contact, tissue thickness, blood flow and phase change with mm to sub mm accuracy are needed. As a proof of principle, we demonstrate that a micro-thermal sensor based on the supported "3ω" technique can achieve this in vitro under idealized conditions in 0.5 to 2 mm thick tissues relevant to cryoablation of the pulmonary vein (PV). To begin with "3ω" sensors were microfabricated onto flat glass as an idealization of a focal probe surface. The sensor was then used to make new measurements of 'k' (W/m.K) of porcine PV, esophagus, and phrenic nerve, all needed for PV cryoabalation treatment planning. Further, by modifying the sensor use from traditional to dynamic mode new measurements related to tissue vs. fluid (i.e. water) contact, fluid flow conditions, tissue thickness, and phase change were made. In summary, the in vitro idealized system data presented is promising and warrants future work to integrate and test supported "3ω" sensors on in vivo deployed focal therapy probe surfaces (i.e. balloons or catheters).
authors.affiliation: Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota, USA.
authors.forename: Harishankar
authors.initials: H
authors.lastname: Natesan
authors.affiliation: Department of Mechanical Engineering, University of California, Berkeley, California, USA.
authors.forename: Wyatt
authors.initials: W
authors.lastname: Hodges
authors.affiliation: Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota, USA.
authors.forename: Jeunghwan
authors.initials: J
authors.lastname: Choi
authors.affiliation: Department of Mechanical Engineering, University of California, Berkeley, California, USA.
authors.forename: Sean
authors.initials: S
authors.lastname: Lubner
authors.affiliation: Department of Mechanical Engineering, University of California, Berkeley, California, USA.
authors.forename: Chris
authors.initials: C
authors.lastname: Dames
authors.affiliation: Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota, USA.
authors.forename: John
authors.initials: J
authors.lastname: Bischof
mesh_terms: D000818:Animals; D003452:Cryosurgery / Q000295:instrumentation*; D004867:Equipment Design; D051379:Mice; D055616:Microtechnology; D008991:Monitoring, Physiologic / Q000295:instrumentation*; D013552:Swine; D013814:Thermal Conductivity