Development of pulsed laser-assisted thermal relaxation technique for thermal characterization of microscale wires

A transient technique is developed to measure the thermal diffusivity of one-dimensional microscale wires. In this technique, the thin wire is suspended over two copper electrodes. Upon fast (nanosecond) pulsed laser irradiation, the wire's temperature will quickly increase to a high level and then decrease gradually. Such temperature decay can be used to determine the sample's thermal diffusivity. To probe this temperature evolution, a dc is fed through the wire to sensor its voltage variation, from which the thermal diffusivity can be extracted. A 25.4 μm thin Pt wire is characterized to verify this technique. Sound agreement is obtained between the measured data and reference value. Applying this pulsed laser-assisted thermal relaxation technique, the thermal diffusivity of multiwall carbon nanotube bundles and microscale carbon fibers is measured. Detailed analysis is conducted to study the effect of the wire embedded in the paste/base on the final measurement result.