Application of the thermal flash technique for low thermal diffusivity micro/nanofibers

The thermal flash method was developed to characterize the thermal diffusivity of micro/nanofibers without concern for thermal contact resistance, which is commonly a barrier to accurate thermal measurement of these materials. Within a scanning electron microscope, a micromanipulator supplies instantaneous heating to the micro/nanofiber, and the resulting transient thermal response is detected at a microfabricated silicon sensor. These data are used to determine thermal diffusivity. Glass fibers of diameter 15 μm had a measured diffusivity of 1.21× 10-7 m2 /s; polyimide fibers of diameters 570 and 271 nm exhibited diffusivities of 5.97× 10-8 and 6.28× 10-8 m2 /s, respectively, which compare favorably with bulk values.