title: Reusable bi-directional 3ω sensor to measure thermal conductivity of 100-μm thick biological tissues.
abstract: Accurate knowledge of the thermal conductivity (k) of biological tissues is important for cryopreservation, thermal ablation, and cryosurgery. Here, we adapt the 3ω method-widely used for rigid, inorganic solids-as a reusable sensor to measure k of soft biological samples two orders of magnitude thinner than conventional tissue characterization methods. Analytical and numerical studies quantify the error of the commonly used "boundary mismatch approximation" of the bi-directional 3ω geometry, confirm that the generalized slope method is exact in the low-frequency limit, and bound its error for finite frequencies. The bi-directional 3ω measurement device is validated using control experiments to within ±2% (liquid water, standard deviation) and ±5% (ice). Measurements of mouse liver cover a temperature ranging from -69 °C to +33 °C. The liver results are independent of sample thicknesses from 3 mm down to 100 μm and agree with available literature for non-mouse liver to within the measurement scatter.
authors: Mechanical Engineering, University of California, Berkeley, Berkeley, California 94720, USA.
authors: Sean D
authors: SD
authors: Lubner
authors: Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors: Jeunghwan
authors: J
authors: Choi
authors: Mechanical Engineering, University of California, Berkeley, Berkeley, California 94720, USA.
authors: Geoff
authors: G
authors: Wehmeyer
authors: Mechanical Engineering, ETH Zurich, Zurich 8092, Switzerland.
authors: Bastian
authors: B
authors: Waag
authors: Mechanical Engineering, University of California, Berkeley, Berkeley, California 94720, USA.
authors: Vivek
authors: V
authors: Mishra
authors: Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors: Harishankar
authors: H
authors: Natesan
authors: Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors: John C
authors: JC
authors: Bischof
authors: Mechanical Engineering, University of California, Berkeley, Berkeley, California 94720, USA.
authors: Chris
authors: C
authors: Dames
mesh_terms: D000818:Animals; D003198:Computer Simulation; D055615:Electrical Equipment and Supplies; D007053:Ice; D008099:Liver / Q000737:chemistry; D051379:Mice; D008954:Models, Biological; D013696:Temperature; D013814:Thermal Conductivity; D014867:Water / Q000737:chemistry
chemical_list: D007053:Ice; D014867:Water