3 ω method to measure thermal properties of electrically conducting small-volume liquid

Abstract

This work presents a method to measure the thermal conductivity and heat capacity of electrically conducting small-volume liquid samples using the 3omega technique. A mathematical model of heat transfer is derived to determine the thermal properties from the 3omega signal considering the device geometry. In order to validate the model, an experimental apparatus has been designed and set up to measure the thermal properties (thermal conductivity and heat capacity) of seven different liquid samples. The results show good agreement with other literature values, demonstrating that the suggested method is effective for measuring the thermal properties of electrically conducting liquids. More importantly, the result with a sample volume of 1 microl demonstrates the resolution of the thermal conductivity as precise as 0.01% which corresponds to a thermal-conductivity change of 10(-4) Wm K in the case of water-based solutions.

Improved 3-omega measurement of thermal conductivity in liquid, gases, and powders using a metal-coated optical fiber

“…Amongst non-steady state techniques for fluid property measurement, THW dominates. 4,8,20 THW analyzes the thermal impulse signal in the time domain, rather than in the frequency domain. THW sends a thermal impulse from a thin heating wire into the surrounding fluid of interest.…”

“…Consequently, a significant part of the 3ω signal comes from the substrate, rather than the fluid under test, which decreases the signal of interest's size. 4 Solid-wire 3ω uses a solid heating wire that is immersed within the sample, rather than a microfabricated heater on a planar substrate. Similar to the standard 3ω, much of the periodic heating propagates radially into the high thermal effusivity metal wire, rather than into surrounding fluid.…”

“…[1][2][3][4][5][6][7][8][9][10] Enhanced thermal property information will aid a diverse range of applications, including improved microprocessor heat removal, 11,12 higher efficiency thermoelectric materials, 13,14 and more effective minimally invasive cryosurgery. 15 The 3ω method and time domain thermo-reflectance (TDTR) are the dominant tools for measuring thermal conductivity in solids, while fluid samples have typically been studied with transient hot-wire (THW).…”

Thermal conductivity of bovine serum albumin: A tool to probe denaturation of protein

“…Application of this method to thermal analysis of small-volume liquid samples has demonstrated that the method is particularly suited for measuring k of samples which are electrically conducting or as small as subnanoliter in volume. [22][23][24] The sensor was inserted into a copper block inside a test chamber (Fig. 1(b)).…”

“…A water bath was used to control the T of the chamber to within 60.1 C. The experimental setup is similar to those used for measuring k of small-volume liquid samples and solid thin films. [22][23][24][25] All measurements were repeated 10 times for each sample to assess the random error. The accuracy of measurement was tested by measuring DI water, ethylene glycol, and methanol; the deviations from reference values 26 were all <3%.…”