Measurement Of Thermal Conduction Through Polymeric Nanowires With The Dual Cantilever Technique

Bi material microcantilevers, with their high sensitivity to thermal stimuli, are ideally suited sensors for investigating nanoscale heat transfer. We have designed and fabricated low theinial conductance bi material microcantilevers by minimizing their width and thickness. Using such cantilevers, we have demonstrated heat flux resolution of less than 1 picowatt. A pair of such cantilevers is proposed as a configuration for measuring thermal conductance of a nanostructure suspended between the two. In this technique, two lasers are focused, one 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 have deteimined the resolution of such a conductance measurement by measuring the background conductance between the two cantilevers in the absence of a nanostructure suspended between them. The background conductance is due to other pathways for heat transfer between the cantilevers besides nanostructure conductance. We have measured the background conductance to be as low as 0.05 nWK(-1).We present measurements of thermal conductance of polystyrene nanowires performed using the dual cantilever technique. The nanowires are fabricated via electrospinning technique with diameters varying in the range of 150 300 nm. While the polystyrene nanowires present a demonstration of the cantilever technique for measuring thermal conductance, the technique we have developed can be extended to other types of nanostructures so long as they can be suspended between two cantilever ends.