Measurements of Thermal Conductance of Suspended Polymeric Nanowires Using Novel Bi-material Cantilever Sensing Technique

摘要

Bi-material microcantilevers are ideally suited sensors for investigating the effects of nanostructuring on thermal transport. We have designed and fabricated high sensitivity bi-material microcantilevers by minimizing their width and thickness dimensions. These cantilevers have been used to resolve sub-picowatt heat flux absorbed on their free end. We propose a pair of such cantilevers as a configuration for measuring thermal conductance of a nanostructure suspended between the two. The technique employs two lasers, one focused on each cantilever. One laser is modulated to vary the temperature at the end of one cantilever, while the second laser senses variation in heat flow through the second cantilever due to thermal conduction along the nanowire. We present measurements of thermal conductance of polystyrene nanowires performed using this dual cantilever technique. The nanowires are fabricated via electrospinning technique with diameters varying in the range of 150 - 300 nm. The measurements demonstrate the efficacy of the technique, which can be used to investigate thermal transport in other types of nanostructures so long as they can be suspended between two cantilever ends.