3 Omega Thermal Conductivity Measurement Setup for 3D Nanostructure

Abstract

In this research, we establish an experimental setup for the thermal conductivity measurement of three-dimensional (3D) carbon nanostructures which will be used as a seawater filter material. The conventional 3-omega (3ω) thermal conductivity measurement method is modified to obtain thermal properties of 3D nanostructures. A nanostructured sample is suspended by being connected to the probe tips of two nanopositioning stages. A Pt heater/sensor is placed on the nanostructured sample to measure the thermal conductivity. A sub-micron diameter platinum (Pt) wire of known temperature coefficient of resistance is heated electrically and used as both a probe and a heater. Suspending a free-standing sample at the center of the wire results in a decrease in the temperature of the probe wire. The thermal conductivity of the sample is obtained by measuring the change in electrical resistance in the probe wire caused by the reduction in temperature. First, AC current is passed with an angular frequency (1ω) through the sample. Joule heating is induced at 2ω frequency, and the temperature of the sample is increased. The temperature coefficient of resistance is obtained by measuring the resistance of the sample that is oscillating at 3ω frequency. The thermal conductivity of the sample is estimated by relating the measured temperature to the imposed heat flux using custom MATLAB program. The results obtained in this research will provide a microscopic understanding on the thermal transport properties of 3D carbon nanostructures that is closely related to the recyclability of 3D carbon as a seawater filter material.